Recommended SI units and conversion factors: Difference between revisions

Latest revision as of 18:22, 26 February 2020

The following tables identify the preferred SI/metric units, along with conversion factors from customary units. Nomenclature for these tables

Space, time

Quantity	SI Unit	Customary Unit	Metric Unit SPE Preferred	Metric Unit Other Allowable	*Conversion Factor:Multiply Customary Unit by Factor To Get Metric Unit**
Length	m	naut mile	km		1.852* E+00
		mile	km		1.609 344* E+00
		chain	m		2.011 68* E+01
		link	m		2.011 68* E−01
		fathom	m		1.828 8* E+00
		m	m		1.0* E+00
		yd	m		9.144* E−01
		ft	m		3.048* E−01
				cm	3.048* E+01
		in.	mm		2.54* E+01
				cm	2.54* E+00
		cm	mm		1.0* E+01
				cm	1.0* E+00
		mm	mm		1.0 E+00
		mil	μm		2.54* E+01
		micron (μ)	μm		1.0* E+00
Length/length	m/m	ft/mi	m/km		1.893 939 E−01
Length/volume	m/m³	ft/U.S. gal	m/m³		8.051 964 E+01
		ft/ft³	m/m³		1.076 391 E+01
		ft/bbl	m/m³		1.917 134 E+00
Area	m²	sq mile	km²		2.589 988 E+00
		section	km²		2.589 988 E+00
				ha	2.589 988 E+02
		acre	m²		4.046 856 E+03
				ha	4.046 856 E−01
		ha	m²		1.0* E+04
		sq yd	m²		8.361 274 E−01
		sq ft	m²		9.290 304* E−02
				cm²	9.290 304* E+02
		sq in.	mm²		6.451 6* E+02
				cm²	6.451 6* E+00
		cm²	mm²		1.0* E+02
				cm²	1.0* E+00
		mm²	mm²		1.0* E+00
Area/volume	m²/m³	ft²	m²/cm³		5.699 291 E−03
Area/mass	m²/kg	cm	m²/kg		1.0* E−01
			m^²/g		1.0* E−04
Volume, capacity	m³	cubem	km³		4.168 182 E+00^[1]†
		acre-ft	m³		1.233 489 E+03
				ha•m	1.233 489 E−01
		m³	m³		1.0* E+00
		cu yd	m³		7.645 549 E−01
		bbl (42 U.S. gal)	m³		1.589 873 E−01
		cu ft	m³		2.831 685 E−02
			dm³	L	2.831 685 E+01
		U.K. gal	m³		4.546 092 E−03
			dm³	L	4.546 092 E+00
		U.S. gal	m³		3.785 412 E−03
			dm³	L	3.785 412 E+00
		liter	dm³	L	1.0* E+00
		U.K. qt	dm³	L	1.136 523 E+00
		U.S. qt	dm³	L	9.463 529 E−01
		U.S. pt	dm³	L	4.731 765 E−01
Volume, capacity	m³	U.K. fl oz	cm³		2.841 308 E+01
		U.S. fl oz	cm³		2.957 353 E+01
		cu in.	cm³		1.638 706 E+01
		mL	cm³		1.0* E+00
Volume/length (linear displacement)	m³/m	bbl/in.	m³/m		6.259 342 E+00
		bbl/ft	m³/m		5.216 119 E−01
		ft³/ft	m³/m		9.290 304* E−02
		U.S. gal/ft	m³/m		1.241 933 E−02
			dm³/m	L/m	1.241 933 E+01
Plane angle	rad	rad	rad		1.0* E+00
		deg (°)	rad		1.745 329 E−02^[2]
				°	1.0* E+00
		min (’)	rad		2.908 882 E−04^[2]
				’	1.0* E+00
		sec (’’)	rad		4.848 137 E−06^[2]
				’’	1.0* E+00
Solid angle	sr	sr	sr		1.0* E+00
Time	s	million years (MY)	Ma		1.0* E+00^[3]
		yr	a		1.0* E+00
		wk	d		7.0* E+00
		d	d		1.0* E+00
		hr	h		1.0* E+00
				min	6.0* E+01
		min	s		6.0* E+01
				h	1.666 667 E−02
				min	1.0* E+00
		s	s		1.0* E+00
		millimicrosecond	ns		1.0* E+00

Mass, amount of substance

Quantity	SI Unit	Customary Unit	Metric Unit SPE Preferred	Metric Unit Other Allowable	*Conversion Factor:Multiply Customary Unit by Factor To Get Metric Unit**
Mass	kg	U.K. ton (long ton)	Mg	t	1.016 047 E+00
		U.S. ton (short ton)	Mg	t	9.071 847 E−01
		U.K. ton	kg		5.080 235 E+01
		U.S. cwt	kg		4.535 924 E+01
		kg	kg		1.0* E+00
		lbm	kg		4.535 924 E−01
		oz (troy)	g		3.110 348 E+01
		oz (av)	g		2.834 952 E+01
		g	g		1.0* E+00
		grain	mg		6.479 891 E+01
		mg	mg		1.0* E+00
		g	g		1.0* E+00
Amount of substance	mol	lbm mol	kmol		4.535 924 E−01
		g mol	kmol		1.0* E−03
		std m³ (0°C, 1 atm)	kmol		4.461 58 E−02^[4]^[5]
		std m³ (15°C, 1 atm)	kmol		4.229 32 E−02^[4]^[5]
		std ft³ (60°F, 1 atm)	kmol		1.195 3 E−03^[4]^[5]

Calorific value, heat, entropy, heat capacity

Quantity	SI Unit	Customary Unit	Metric Unit SPE Preferred	Metric Unit Other Allowable	*Conversion Factor:Multiply Customary Unit by Factor To Get Metric Unit**
Calorific value (mass basis)	J/kg	Btu/lbm	MJ/kg		2.326 E−03
			kJ/kg	J/g	2.326 E+00
				(kW•h)/kg	6.461 112 E−04
		cal/g	kJ/kg	J/g	4.184* E+00
		cal/lbm	J/kg		9.224 141 E+00
Calorific value (mole basis)	J/mol	kcal/g mol	kJ/kmol		4.184* C+03^[5]
		Btu/lbm mol	MJ/kmol		2.326 E−03^[5]
			kJ/kmol		2.326 E+00^[5]
Calorific value(volume basis–solids and liquids)	J/m3	therm/U.K. gal	MJ/m3	kJ/dm3	2.320 80 E+04
			kJ/m3		2.320 80 E+07
				(kW•h)/dm3	6.446 660 E+00
		Btu/U.S. gal	MJ/m3	kJ/dm3	2.787 163 E−01
			kJ/m3		2.787 163 E+02
				(kW•h)/m3	7.742 119 E−02
		Btu/U.K. gal	MJ/m3	kJ/dm3	2.320 8 E−01
			kJ/m3		2.320 8 E+02
				(kW•h)/m3	6.446 660 E−02
		Btu/ft3	MJ/m3	kJ/dm3	3.725 895 E−02
			kJ/m3		3.725 895 E+01
				(kW•h)/m3	1.034 971 E−02
		kcal/m3	MJ/m3	kJ/dm3	4.184* E−03
			kJ/m3		4.184* E−03
		cal/mL	MJ/m3		4.184* E+00
		ft-lbf/U.S. gal	kJ/m3		3.581 692 E−01
Calorific value (volume basis–gases)	J/m3	cal/mL	kJ/m3	J/dm3	4.184* E+03
		kcal/m3	kJ/m3	J/dm3	4.184* E+00
		Btu/ft3	kJ/m3	J/dm3	3.725 895 E+01
				(kW•h)/m3	1.034 971 E−02
Specific entropy	J/kg•K	Btu/(lbm-°R)	kJ(kg•K)	J(g•K)	4.186 8* E+00
		cal/(g-°K)	kJ(kg•K)	J(g•K)	4.184* E+00
		kcal/(kg-°C)	kJ(kg•K)	J(g•K)	4.184* E+00
Specific heat	J/kg•K	kW-hr/(kg-°C)	kJ(kg•K)	J(g•K)	3.6* E+03
capacity (mass basis)		Btu/(lbm-°F)	kJ(kg•K)	J(g•K)	4.186 8* E+00
		kcal(kg-°C)	kJ(kg•K)	J(g•K)	4.184* E+00
Molar heat	J/mol•K	Btu/(lbm mol-°F)	kJ(kmol•K)		4.186 8* E+00^[5]
capacity		cal/(g mol-°C)	kJ(kmol•K)		4.184* E−00^[5]

Temperature, pressure, vacuum

Quantity	SI Unit	Customary Unit	Metric Unit SPE Preferred	Metric Unit Other Allowable	*Conversion Factor:Multiply Customary Unit by Factor To Get Metric Unit**
Temperature (absolute)	K	°R	K		5/9
		°K	K		1.0* E+00
Temperature (traditional)	K	°F	°C		(F−32)/1.8
		°C	°C		1.0* E+00
Temperature (difference)	K	°F	K	°C	5/9 E+00
		°C	K	°C	1.0* E+00
Temperature/length (geothermal gradient)	K/m	°F/100 ft	mK/m		1.822 689 E+01
Length/temperature (geothermal step)	m/K	ft°F	m/K		5.486 4* E−01
Pressure	Pa	atm (760 mm Hg at 0°C or 14.696 (lbf/in.2)	MPa		1.013 25* E−01
			kPa		1.013 25* E+02
				bar	1.013 25* E+00
		bar	MPa		1.0* E−01
			kPa		1.0* E+02
				bar	1.0* E+00
		at (technical atm, kbf/cm2)	MPa		9.806 65* E−02
			kPa		9.806 65* E+01
				bar	9.806 65* E−01
Pressure	Pa	lbf/in.2 (psi)	MPa		6.894 757 E−03
			kPa		6.894 757 E+00
				bar	6.894 757 E−02
		in. Hg (32°F)	kPa		3.386 38 E+00
		in. Hg (60°F)	kPa		3.376 85 E+00
		in. H2O (39.2°F)	kPa		2.490 82 E−01
		in. H2O (60°F)	kPa		2.488 4 E−01
		Mm Hg (0°C)=torr	kPa		1.333 224 E−01
		Cm H2O (4°C)	kPa		9.806 38 E−02
		lbf/ft2 (psf)	kPa		4.788 026 E−02
		µm Hg (0°C)	Pa		1.333 224 E−01
		µbar	Pa		1.0* E−01
		dyne/cm2	Pa		1.0* E−01
Vacuum, draft	Pa	in. Hg (60°F)	kPa		3.376 85 E+00
		in. H2O (39.2°F)	kPa		2.490 82 E−01
		Mm Hg (0°C)=torr	kPa		1.333 224 E−01
		Cm H2O (4°C)	kPa		9.806 38 E−02
Liquid heat	m	ft	m		3.048* E−01
		in.	mm		2.54* E+01
				cm	2.54* E+00
Pressure drop/length	Pa/m	psi/ft	kPa/m		2.262 059 E+01
		psi/100 ft	kPa/m		2.262 059 E−01

Density, specific volume, concentration, dosage

Quantity	SI Unit	Customary Unit	Metric Unit SPE Preferred	Metric Unit Other Allowable	*Conversion Factor:Multiply Customary Unit by Factor To Get Metric Unit**
Density (gases)	kg/m³	lbm/ft³	kg/m³		1.601 846 E+01
			g/m³		1.601 846 E+04
Density (liquids)	kg/m³	lbm/U.S. gal	kg/m³		1.198 264 E+02
				g/cm³	1.198 264 E−01
		lbm/U.K. gal	kg/m³		9.997 633 E+01
				kg/dm³	9.977 633 E−02
		lbm/ft³	kg/m³		1.601 846 E+01
				g/cm³	1.601 846 E−02
		g/cm³	kg/m³		1.0* E+03
				kg/dm³	1.0* E+00
		°API	g/cm³		141.5/(131.5+°API)
Density (solids)	kg/m³	lbm/ft³	kg/m³		1.601 846 E+01
Specific volume(gases)	m³/kg	ft³/lbm	m³/kg		6.242 796 E−02
			m³/g		6.242 796 E−05
Specific volume (liquids)	m³/kg	ft³/lbm	dm³/kg		6.242 796 E+01
		U.K. gal/lbm	dm³/kg	cm³/g	1.002 242 E+01
		U.S. gal/lbm	dm³/kg	cm³/g	8.345 404 E+00
Specific volume (mole basis)	ft³/mol	L/g mol	m³/kmol		1.0* E+00^[5]
		ft³/lbm mol	m³/kmol		6.242 796 E−02^[5]
Specific volume (clay yield)	m³/kg	bbl/U.S. ton	m³/t		1.752 535 E−01
		bbl/U.K. ton	m³/t		1.564 763 E−01
Yield (shale distillation)	m³/kg	bbl/U.S. ton	dm³/t	L/t	1.752 535 E+02
		bbl/U.K. ton	dm³/t	L/t	1.564 763 E+02
		U.S. gal/U.S. ton	dm³/t	L/t	4.172 702 E+00
		U.S. gal/U.K. ton	dm³/t	L/t	3.725 627 E+00
Concentration(mass/mass)	kg/kg	wt%	kg/kg		1.0* E−02
			g/kg		1.0* E+01
		wt ppm	mg/kg		1.0* E+00
Concentration(mass/volume)	kg/m³	lbm/bbl	kg/m³	g/dm³	2.853 010 E+00
		g/U.S. gal	kg/m³		2.641 720 E−01
		g/U.K. gal	kg/m³	g/L	2.199 692 E−01
Concentration(mass volume)	kg/m³	lbm/1,000 U.S. gal	g/m³	mg/dm³	1.198 264 E+02
		lbm/1,000 U.K. gal	g/m³	mg/dm³	9.977 633 E+01
		grains/U.S. gal	g/m³	mg/dm³	1.711 806 E+01
		grains/ft³	mg/m³		2.288 352 E+03
		lbm/1,000 bbl	g/m³	mg/dm³	2.853 010 E+00
		mg/U.S. gal	g/m³	mg/dm³	2.641 720 E−01
		grains/100 ft³	mg/m³		2.288 352 E+01
Concentration(volume/volume)	m³/ m³	bbl/bbl	m³/m³		1.0* E+00
		ft³/ft³	m³/m³		1.0* E+00
		bbl/acre-ft	m³/m³		1.288 923 E−04
				m³/ha•m	1.288 923 E+00
		vol %	m³/m³		1.0* E−02
		U.K. gal/ft³	dm³/m³	L/m³	1.605 437 E+02
		U.S. gal/ft³	dm³/m³	L/m³	1.336 806 E+02
		mL/U.S. gal	dm³/m³	L/m³	2.641 720 E−01
		mL/U.K. gal	dm³/m³	L/m³	2.199 692 E−01
		vol ppm	cm³/m³		1.0* E+00
			dm³/m³	L/m³	1.0* E−03
		U.K. gal/1,000 bbl	cm³/m³		1.859 406 E+01
		U.S. gal/1,000 bbl	cm³/m³		2.380 952 E+01
		U.K. pt/1,000 bbl	cm³/m^³		3.574 253 E+00
Concentration	mol/m3	lbm mol/U.S. gal	kmol/m3		1.198 264 E+02
		lbm mol/U.K. gal	kmol/m3		9.977 633 E+01
		lbm mol/ft3	kmol/m		1.601 846 E+01
		std ft3 (60°F,1 atm)/bbl	kmol/m3		7.518 18 E−03
Concentration(volume/mole)	m3/mol	U.S. gal/1,000 std ft3 (60°F/60°F)	dm3/kmol	L/kmol	3.166 93 E+00
		bbl/million std ft3 (60°F/60°F)	dm3/kmol	L/kmol	1.330 11 E−01

Facility throughput, capacity

Quantity	SI Unit	Customary Unit	Metric Unit SPE Preferred	Metric Unit Other Allowable	*Conversion Factor:Multiply Customary Unit by Factor To Get Metric Unit**
Throughput (mass basis)	kg/s	million lbm/yr	t/a	Mg/a	4.535 924 E+02
		U.K. ton/yr	t/a	Mg/a	1.016 047 E+00
		U.S. ton/yr	t/a	Mg/a	9.071 847 E−01
		U.K. ton/D	t/d	Mg/d	1.016 047 E+00
				t/h, Mg/h	4.233 529 E−02
		U.S. ton/D	t/d		9.071 847 E−01
				t/h, Mg/h	3.779 936 E−02
		U.K. ton/hr	t/h	Mg/h	1.016 047 E+00
		U.S. ton/hr	t/h	Mg/h	9.071 847 E−01
		lbm/hr	kg/h		4.535 924 E−01
Throughput (volume basis)	m³/s	bbl/D	t/a		5.803 036 E+01^[6]
				m³/d	1.589 873 E−01
			m³/h		6.624 471 E−03
		ft³/D	m³/d		2.831 685 E−02
		bbl/hr	m³/h		1.589 873 E−01
		ft³/h	m³/h		2.831 685 E−02
		U.K. gal/hr	m³/h		4.546 092 E−03
				L/s	1.262 803 E−03
		U.S. gal/hr	m³/h		3.785 412 E−03
				L/s	1.051 503 E−03
		U.K. gal/min	m³/h		2.727 655 E−01
				L/s	7.576 819 E−02
		U.S. gal/min	m³/h		2.271 247 E−01
				L/s	6.309 020 E−02
Throughput (mole basis)	mol/s	lbm mol/hr	kmol/h		4.535 924 E−01
				kmol/s	1.259 979 E−04^[7]
Pipeline capacity	m³/m	bbl/mile	m³/km		9.879 013 E−02
Flow rate (mass basis)	kg/s	U.K. ton/min	kg/s		1.693 412 E+01
		U.S. ton/min	kg/s		1.511 974 E+01
		U.K. ton/hr	kg/s		2.822 353 E−01
		U.S. ton/hr	kg/s		2.519 958 E−01
		U.K. ton/D	kg/s		1.175 980 E−02
		U.S. ton/D	kg/s		1.049 982 E−02
		million lbm/yr	kg/s		5.249 912 E+02
		U.K. ton/yr	kg/s		3.221 864 E−05
		U.S. ton/yr	kg/s		2.876 664 E−05
		lbm/s	kg/s		4.535 924 E−01
		lbm/min	kg/s		7.559 873 E−03
		lbm/hr	kg/s		1.259 979 E−04
Flow rate (volume basis)	m³/s	bbl/D	m³/d		1.589 873 E−01
				L/s	1.840 131 E−03
		ft³/D	m³/d		2.831 685 E−02
				L/s	3.277 413 E−04
		bbl/hr	m3/s		4.416 314 E−05
				L/s	4.416 314 E−02
		ft³/hr	m³/s		7.865 791 E−06
				L/s	7.865 791 E−03
		U.K. gal/hr	dm³/s	L/s	1.262 803 E−03
		U.S. gal/hr	dm³/s	L/s	1.051 503 E−03
		U.K. gal/min	dm³/s	L/s	7.576 820 E−02
		U.S. gal/min	dm3/s	L/s	6.309 020 E−02
		ft³/min	dm³/s	L/s	4.719 474 E−01
		ft³/s	dm³/s	L/s	2.831 685 E+01
Flow rate (mole basis)	mol/s	lbm mol/s	kmol/s		4.535 924 E−0113
		lbm mol/hr	kmol/s		1.259 979 E−0413
		million scf/D	kmol/s		1.383 449 E−0213
Flow rate/length (mass basis)	kg/s•m	lbm/(s-ft)	kg/(s•m)		1.488 164 E+00
		lbm/(hr-ft)	kg/(s•m)		4.133 789 E−04
Flow rate/length	m²/s	U.K. gal/(min-ft)	m²/s	m³/(s•m)	2.485 833 E−04
		U.S. gal/(min-ft)	m²/s	m³/(s•m)	2.069 888 E−04
		U.K. gal/(hr-in.)	m²/s	m³/(s•m)	4.971 667 E−05
		U.S. gal/(hr-in.)	m²/s	m³/(s•m)	4.139 776 E−05
		U.K. gal/(hr-ft)	m²/s	m³/(s•m)	4.143 055 E−06
		U.S. gal/(hr-ft)	m²/s	m³/(s•m)	3.449 814 E−06
Flow rate/area (mass basis)	kg/s•m²	lbm/(s-ft²)	kg/s•m²		4.882 428 E+00
		lbm/(hr-ft2)	kg/s•m²		1.356 230 E−03

Flow rate

Quantity	SI Unit	Customary Unit	Metric Unit SPE Preferred	Metric Unit Other Allowable	*Conversion Factor:Multiply Customary Unit by Factor To Get Metric Unit**
Flow rate/area	m/s	ft³/(s-ft²)	m/s	m³/(s•m²)	3.048* E−01
		ft³/(min-ft²)	m/s	m³/(s•m²)	5.08* E−03
		U.K. gal/(hr-in.²)	m/s	m³/(s•m²)	1.957 349 E−03
		U.S. gal/(hr-in.²)	m/s	m³/(s•m²)	1.629 833 E−03
		U.K. gal/(min-ft²)	m/s	m³/(s•m²)	8.155 621 E−04
		U.S. gal/(min-ft²)	m/s	m³/(s•m²)	6.790 972 E−04
		U.K. gal/(hr-ft²)	m/s	m³/(s•m²)	1.359 270 E−05
		U.S. gal/(hr-ft²)	m/s	m³/(s•m²)	1.131 829 E−05
Flow rate/pressure drop (productivity index)	m³/s•Pa	bbl/(D-psi)	m³/(d•kPa)		2.305 916 E−02

Energy, work, power

Quantity	SI Unit	Customary Unit	Metric Unit SPE Preferred	Metric Unit Other Allowable	*Conversion Factor:Multiply Customary Unit by Factor To Get Metric Unit**
Energy, work	J	quad	MJ		1.055 056 E+12
			TJ		1.055 056 E+06
			EJ		1.055 056 E+00
				MW•h	2.930 711 E+08
				GW•h	2.930 711 E+05
				TW•h	2.930 711 E+02
		therm	MJ		1.055 056 E+02
			kJ		1.055 056 E+05
				kW•h	2.930 711 E+01
		U.S. tonf-mile	MJ		1.431 744 E+01
		hp-hr	MJ		2.684 520 E+00
			kJ		2.684 520 E+03
				kW•h	7.456 999 E−01
		ch-hr or CV-hr	MJ		2.647 796 E+00
			Kj		2.647 796 E+03
				kW•h	7.354 99 E−01
		kW-hr	MJ		3.6* E+00
			kJ		3.6* E+03
		Chu	kJ		1.899 101 E+00
				kW•h	5.275 280 E−04
		Btu	kJ		1.055 056 E+00
				kW•h	2.930 711 E−04
		kcal	kJ		4.184* E+00
		cal	kJ		4.184* E−03
		ft-lbf	kJ		1.344 818 E−03
		lbf-ft	kJ		1.355 818 E−03
		J	kJ		1.0* E−03
		lbf-ft²/s^²	kJ		4.214 011 E−05
		erg	J		1.0* E−07
Impact energy	J	kgf•m	J		9.806 650* E+00
		lbf-ft	J		1.355 818 E+00
Work/length	J/m	U.S. tonf-mile/ft	MJ/m		4.697 322 E+01
Surface energy	J/m²	erg/cm²	mJ/m²		1.0* E+00
Specific impact	J/m²	kgf•m/cm²	J/cm²		9.806 650* E−00
energy Power		lbf•ft/in.²	J/cm²		2.101 522 E−01
	W	quad/yr	MJ/a		1.055 056 E+12
			TJ/a		1.055 056 E+06
			EJ/a		1.055 056 E+00
		erg/a	TW		3.170 979 E−27
			GW		3.170 979 E−24
		million Btu/hr	MW		2.930 711 E−01
		ton of refrigeration	kW		3.516 853 E+00
		Btu/s	kW		1.055 056 E+00
		kW	kW		1.0* E+00
		hydraulic horsepower—hhp	kW		7.460 43 E−01
		hp (electric)	kW		7.46* E−01
		hp (550 ft-lbf/s)	kW		7.456 999 E−01
		ch or CV	kW		7.354 99 E−01
		Btu/min	kW		1.758 427 E−02
		ft•lbf/s	kW		1.355 818 E−03
		kcal/hr	W		1.162 222 E+00
		Btu/hr	W		2.930 711 E−01
		ft•lbf/min	W		2.259 697 E−02
Power/area	W/m²	Btu/s•ft²	kW/m²		1.135 653 E+01
		cal/hr•cm²	kW/m²		1.162 222 E−02
		Btu/hr•ft²	kW/m²		3.154 591 E−03
Heat flow unit—hfu		µcal/s•cm²	mW/m²		4.184* E+01
(geothermics)
Heat release rate,	W/m²	hp/ft³	kW/m³		2.633 414 E+01
mixing power		cal/(hr•cm³)	kW/m³		1.162 222 E+00
		Btu/(s•ft³)	kW/m³		3.725 895 E+01
		Btu/(hr•ft³)	kW/m³		1.034 971 E−02
Heat generation unit—hgu (radioactive rocks)		cal/(s•cm³)	µW/m³		4.184* E+12
Cooling duty (machinery)	W/W	Btu/(bhp-hr)	W/kW		3.930 148 E−01
Specific fuel consumption (mass basis)	kg/J	lbm/(hp-hr)	mg/J	kg/MJ	1.689 659 E−01
				kg/(kW•h)	6.082 774 E−01
Specific fuel consumption (volume basis)	m³/J	m³/(kW-hr)	dm³/MJ	mm³/J	2.777 778 E+02
				dm³/(kW•h)	1.0* E+03
		U.S. gal/(hp-hr)	dm³/MJ	mm³/J	1.410 089 E+00
				dm³(kW•h)	5.076 321 E+00
		U.K. pt/(hp-hr)	dm³/MJ	mm3/J	2.116 809 E−01
				dm³/(kW•h)	7.620 512 E−01
Fuel consumption (automotive)	m³/m	U.K. gal/mile	dm3/100 km	L/100 km	2.824 811 E+02
		U.S. gal/mile	dm³/100 km	L/100 km	2.352 146 E+02
		mile/U.S. gal	km/dm³	km/L	4.251 437 E−01
		mile/U.K. gal	km/dm³	km/L	3.540 060 E−01

Mechanics

Quantity	SI Unit	Customary Unit	Metric Unit SPE Preferred	Metric Unit Other Allowable	*Conversion Factor:Multiply Customary Unit by Factor To Get Metric Unit**
Velocity (linear),	m/s	knot	km/h		1.852* E+00
speed		mile/hr	km/h		1.609 344* E+00
		m/s	m/s		1.0* E+00
		ft/s	m/s		3.048* E−01
				cm/s	3.048* E+01
				m/ms	3.048* E−04^[8]
		ft/min	m/s		5.08* E−03
				cm/s	5.08* E−01
		ft/hr	mm/s		8.466 667 E−02
				cm/s	8.466 667 E−03
		ft/D	mm/s		3.527 778 E−03
				m/d	3.048* E−01
		in.	mm/s		2.54* E+01
				cm/s	2.54* E+00
		in./min	mm/s		4.233 333 E−01
				cm/s	4.233 333 E−02
Velocity (angular)	rad/s	rev/min	rad/s		1.047 198 E−01
		rev/s	rad/s		6.283 185 E+00
		degree/min	rad/s		2.908 882 E−04
Interval transit time	s/m	s/ft	s/m	µs/m	3.280 840 E+00^[9]
Corrosion rate	m/s	in./yr (ipy)	mm/a		2.54* E+01
		mil/yr	mm/a		2.54* E−02
Rotational frequency	rev/s	rev/s	rev/s		1.0* E+00
		rev/min	rev/s		1.666 667 E−02
		rev/min	rad/s		1.047 198 E−01
Acceleration (linear)	m/s²	ft/s²	m/s²		3.048* E−01
				cm/s²	3.048* E+01
		gal(cm/s²)	m/s²		1.0* E−02
Acceleration(rotational)	rad/s²	rad/s²	rad/s²		1.0* E+00
		rpm/s	rad/s^²		1.047 198 E−01
Momentum	kg•m/s	lbm•ft/s	kg•m/s		1.382 550 E−01
Force	N	U.K. tonf	kN		9.964 016 E+00
		U.S. tonf	kN		8.896 443 E+00
		kgf (kp)	N		9.806 650* E+00
		lbf	N		4.448 222 E+00
		N	N		1.0* E+00
		pdl	mN		1.382 550 E+02
		dyne	mN		1.0* E−02
Bending moment,	N•m	U.S. tonf-ft	kN•m		2.711 636 E+00^[10])
torque		kgf-m	N•m		9.806 650* E+00^[10]
		lbf-ft	N•m		1.355 818 E+00^[10]
		lbf-in.	N•m		1.129 848 E−01^[10]
		pdl-ft	N•m		4.214 011 E−02^[10]
Bending moment/	N•m/m	(lbf-ft)/in.	(N•m)/m		5.337 856 E+01^[10]
length		(kgf-m)/m	(N•m)/m		9.806 650* E+00^[10]
		(lbf-in.)/in.	(N•m)/m		4.448 222 E+00^[10]
Elastic modul (Young’s, shear bulk)	Pa	lbf/in.²	GPa		6.894 757 E−06
Moment of inertia	kg•m²	lbm-ft²	kg•m²		4.214 011 E−02
Moment of section	m⁴	in.⁴	cm⁴		4.162 314 E+01
Section modulus	m³	cu in.	cm³		1.638 706 E+01
		cu ft	cm³		1.638 706 E+04
				mm³	2.831 685 E+04
				m³	2.831 685 E−02
Stress	Pa	U.S. tonf/in.²	MPa	N/mm²	1.378 951 E+01
		kgf/mm²	MPa	N/mm²	9.806 650* E+00
		U.S. tonf/ft²	MPa	N/mm²	9.576 052 E−02
		lbf/in.² (psi)	MPa	N/mm²	6.894 757 E−03
		lbf/ft² (psf)	kPa		4.788 026 E−02
		dyne/cm²	Pa		1.0* E−01
Yield point, gel strength (drilling fluid)		lbf/100 ft²	Pa		4.788 026 E−01
Mass/length	kg/m	lbm/ft	kg/m		1.488 164 E+00
Mass/area	kg/m2	U.S. ton/ft²	Mg/m²		9.764 855 E+00
structural loading, bearing capacity (mass basis)		lbm/ft²	kg/m²		4.882 428 E+00
Coefficient of thermal expansion	m/(m•K)	in./(in.-°F)	mm/(mm•K)		5.555 556 E−01

Transport properties

Quantity	SI Unit	Customary Unit	Metric Unit SPE Preferred	Metric Unit Other Allowable	*Conversion Factor:Multiply Customary Unit by Factor To Get Metric Unit**
Diffusivity	m²/s	ft²/s	mm²/s		9.290 304* E+04
		cm²/s	mm²/s		1.0* E+02
		ft²/hr	mm²/s		2.580 64* E+01
Thermal resistance	(k•m²)/W	(°C-m²•hr)/kcal	(K•m²)kW		8.604 208 E+02
		(°F-ft² hr)/Btu	(K•m²)kW		1.761 102 E+02
Heat flux	W/m²	Btu/(hr-ft²)	kW/m²		3.154 591 E−03
Thermal conductivity	W/(m•K)	(cal/s-cm²-°C/cm	W/(m•K)		4.184* E+02
		Btu/(hr-ft²-°F/ft)	W/(m•K)		1.730 735 E+00
				kJ•m/(h•m²K)	6.230 646 E+00
		kcal/(hr-m²-°C/m)	W/(m•K)		1.162 222 E+00
		Btu/(hr-ft²-°F/in.)	W/(m•K)		1.442 279 E−01
		cal/(hr-cm²-°C/cm)	W/(m•K)		1.162 222 E−01
Heat transfer coefficient	W/(m²•K)	cal/(s-cm²-°C)	kW/(m²•K)		4.184* E+01
		Btu/(s-ft²-°F)	kW/(m²•K)		2.044 175 E+01
		cal/(hr-cm²-°C)	kW/(m²•K)		1.162 222 E−02
		Btu/(hr-ft²-°F)	kW/(m²•K)		5.678 263 E−03
				kJ(h•m²•K)	2.044 175 E+01
		Btu/(hr-ft²-°R)	kW/(m²•K)		5.678 263 E−03
		kcal/(hr-m²-°C)	kW/(m²•K)		1.162 222 E−03
Volumetric heat	kW/(m³•K)	Btu/(s-ft³-°F)	kW/(m³•K)		6.706 611 E+01
transfer coefficient		Btu/(hr-ft³-°F)	kW/(m³•K)		1.862 947 E−02
Surface tension	N/m	dyne/cm	mN/m		1.0* E+00
Viscosity (dynamic)	Pa•s	(lbf-s)/in.²	Pa•s	(N•s)/m²	6.894 757 E+03
		(lbf-s)/ft²	Pa•s	(N•s)/m²	4.788 026 E+01
		(kgf-s)/m²	Pa•s	(N•s)/m²	9.806 650* E+00
		lbm/(ft-s)	Pa•s	(N•s)/m²	1.488 164 E+00
		(dyne-s)/cm²	Pa•s	(N•s)/m²	1.0* E−01
		cp	Pa•s	(N•s)/m²	1.0* E−03
		lbm/(ft-hr)	Pa•s	(N•s)/m²	4.133 789 E−04
Viscosity (kinematic)	m²/s	ft²/s	mm²/s		9.290 304* E+04
		in.²/s	mm²/s		6.451 6* E+02
		m²/hr	mm²/s		2.777 778 E+02
		cm²/s	mm²/s		1.0* E+02
		ft²/hr	mm²/s		2.580 64* E+01
		cSt	mm²/s		1.0* E+00
Permeability	m²	darcy	μm²		9.869 233 E−01^[11]
		millidarcy	μm²		9.869 233 E−04^[11]
				10⁻³μm²	9.869 233 E−01^[11]

Electricity, magnetism

Quantity	SI Unit	Customary Unit	Metric Unit SPE Preferred	Metric Unit Other Allowable	*Conversion Factor:Multiply Customary Unit by Factor To Get Metric Unit**
Admittance	S	S	S		1.0* E+00
Capacitance	F	μF	μF		1.0* E+00
Capacity, storage battery	C	A•hr	kC		3.6* E+00
Charge density	C/m³	C/mm³	C/mm³		1.0* E+00
Conductance	S	S	S		1.0* E+00
		Ω(mho)	S		1.0* E+00
Conductivity	S/m	S/m	S/m		1.0* E+00
		Ω/m	S/m		1.0* E+00
		m Ω/m	mS/m		1.0* E+00
Current density	A/m²	A/mm²	A/mm²		1.0* E+00
Displacement	C/m²	C/cm²	C/cm^²		1.0 E+00
Electric charge	C	C	C		1.0* E+00
Electric current	A	A	A		1.0* E+00
Electric dipole moment	C•m	C•m	C•m		1.0* E+00
Electric field strength	V/m	V/m	V/m		1.0* E+00
Electric flux	C	C	C		1.0* E+00
Electric polarization	C/m²	C/m²	C/m²		1.0* E+00
Electric potential	V	V	V		1.0* E+00
		mV	mV		1.0* E+00
Electromagnetic moment	A•m²	A•m²	A•m²		1.0* E+00
Electromotive force	V	V	V		1.0* E+00
Flux of displacement	C	C	C		1.0* E+00
Frequency	Hz	cycles/s	Hz		1.0* E+00
Impedance	Ω	Ω	Ω		1.0* E+00
Interval transit time	s/m	μs/ft	μs/m		3.280 840 E+00
Linear current density	A/m	A/mm	A/mm		1.0* E+00
Magnetic dipole moment	Wb•m	Wb•m	Wb•m		1.0* E+00
Magnetic field strength	A/m	A/mm	A/mm		1.0* E+00
		oersted	A/m		7.957 747 E+01
		gamma	A/m		7.957 747 E−04
Magnetic flux	Wb	mWb	mWb		1.0* E+00
Magnetic flux density	T	mT	mT		1.0* E+00
		gauss	T		1.0* E−04
Magnetic induction	T	mT	mT		1.0* E+00
Magnetic moment	A•m²	A•m²	A•m^²		1.0* E+00
Magnetic polarization	T	mT	mT		1.0* E+00
Magnetic potential difference	A	A	A		1.0* E+00
Magnetic vector potential	Wb/m	Wb/m	Wb/m		1
Magnetization	A/m	A/mm	A/mm		1
Modulus of admittance	S	S	S		1
Modulus of impedance	Ω	Ω	Ω		1
Mutual inductance	H	H	H		1
Permeability	H/m	µH/m	µH/m		1
Permeance	H	H	H		1
Permittivity	F/m	µF/m	µF/m		1
Potential difference	V	V	V		1
Quantity of electricity	C	C	C		1
Reactance	Ω	Ω	Ω		1
Reluctance	H^–1	H^–1	H^–1		1
Resistance	Ω	Ω	Ω		1
Resistivity	Ω•m	Ω•cm	Ω•cm		1
		Ω•m	Ω•m		1 ^[12]
Self inductance	H	mH	mH		1
Surface density of charge	C/m²	mC/m²	mC/m²		1
Susceptance	S	S	S		1
Volume density of charge	C/m³	C/mm³	C/mm^³		1

Acoustic, light, radiation

Quantity	SI Unit	Customary Unit	Metric Unit SPE Preferred	Metric Unit Other Allowable	*Conversion Factor:Multiply Customary Unit by Factor To Get Metric Unit**
Absorbed dose	Gy	rad	Gy		1.0* E−02
Acoustical energy	J	J	J		1
Acoustical intensity	W/m²	W/cm²	W/m²		1.0* E+04
Acoustical power	W	W	W		1
Sound pressure	N/m²	N/m²	N/m²		1
Illuminance	lx	footcandle	lx		1.076 391 E+01
Illumination	lx	footcandle	lx		1.076 391 E+01
Irradiance	W/m²	W/m²	W/m²		1
Light exposure	lx•s	footcandle•s	lx•s		1.076 391 E+01
Luminance	cd/m²	cd/m²	cd/m²		1
Luminous efficacy	lm/W	lm/W	lm/W		1
Luminous exitance	lm/m²	lm/m²	lm/m²		1
Luminous flux	lm	lm	lm		1
Luminous intensity	cd	cd	cd		1
Quantity of light	ℓm•s	talbot	ℓm•s		1.0* E+00
Radiance	W/(m²•sr)	W/(m²•sr)	W/(m^²•sr)		1
Radiant energy	J	J	J		1
Radiant flux	W	W	W		1
Radiant intensity	W/sr	W/sr	W/sr		1
Radiant power	W	W	W		1
Wavelength	m	Å	nm		1.0* E−01
Capture unit	m⁻¹	10⁻³cm⁻¹	m⁻¹		1.0* E+01
				10⁻³cm⁻¹	1
		m⁻¹	m⁻¹		1
Radioactivity		curie	Bq		3.7* E+10
Capillary	Pa	ft (fluid)	m (fluid)		3.048* E−01
Compressibility of	Pa⁻¹	psi⁻¹	Pa⁻¹		1.450 377 E−04
reservoir fluid				kPa⁻¹	1.450 377 E−01
Corrosion allowance	m	in.	mm		2.54* E+01
Corrosion rate	m/s	mil/yr	mm/a		2.54* E−02
		(mpy)
Differential orifice	Pa	in. H₂O	kPa		2.488 4 E−01
pressure		(at 60°F)		cm H₂O	2.54* E+00
Gas-oil ratio	m³/m³	scf/bbl	"standard"		1.801 175 E−01^[1]
			m³/m³
Gas rate	m³/s	scf/D	"standard"		2.863 640 E−02^[1]
			m³/d
Geologic time	s	yr	Ma
Heat (fluid mechanics)	m	ft	m		3.048* E−01
				cm	3.048* E+01
Heat exchange rate	W	Btu/hr	kW		2.930 711 E−04
				kJ/h	1.055 056 E+00
Mobility	m²/Pa•s	d/cp	µm²/mPa•s		9.869 233 E−01
				µm²/Pa•s	9.869 233 E+02
Net pay thickness	m	ft	m		3.048* E−01
Oil rate	m3/s	bbl/D	m3/d		1.589 873 E−01
		short ton/yr	mg/a	ta	9.071 847 E−01
Particle size	m	micron	µm		1.0*
Permeability-thickness	m³	md-ft	md•m	µm²•m	3.008 142 E−04
Pipe diameter (actual)	m	in.	cm		2.54* E+00
				mm	2.54* E+01
Pressure buildup	Pa	psi	kPa		6.894 757 E+00^[2]
per cycle
Productivity index	m³/Pa•s	bbl/(psi-D)	m³(kPa•d)		2.305 916 E−02^[2]
Pumping rate	m³/s	U.S. gal/min	m3/h		2.271 247 E−01
				L/s	6.309 020 E−02
Revolutions per minute	rad/s	rpm	rad/s		1.047 198 E−01
				rad/m	6.283 185 E+00
Recovery/unit volume	m³/m³	bbl/(acre-ft)	m³/m³		1.288 931 E−04
(oil)				m³/ha•m	1.288 931 E+00
Reservoir area	m²	sq mile	km²		2.589 988 E+00
		acre		ha	4.046 856 E−01
Reservoir volume	m³	acre-ft	m³		1.233 482 E+03
				ha•m	1.233 482 E−01
Specific productivity	m³/Pa•s•m	bbl/(D-psi-ft)	m³/(kPa•d•s)		7.565 341 E−02^[2]
index
Surface or interfacial tension in reservoir capillaries	N/m	dyne/cm	mN/m		1.0* E+00
Torque	N•m	lbf-ft	N•m		1.355 818 E+00^[3]
Velocity (fluid flow)	m/s	ft/s	m/s		3.048* E−01
Vessel diameter	m
1–100 cm		in.	cm		2.54* E+00
above 100 cm		ft	m		3.048* E−01

*An asterisk indicates the conversion factor is exact using the numbers shown; all subsequent numbers are zeros.

References

↑ ^1.0 ^1.1 ^1.2 Since 1893, the U.S. basis of length measurement has been derived from metric standards. In 1959, a small refinement was made in the definition of the yard to resolve discrepancies both in this country and abroad, which changed its length from 3600/3937 m to 0.9144 m exactly. This resulted in the new value being shorter by two parts in a million. At the same time, it was decided that any data in feet derived from and published as a result of geodetic surveys within the U.S. would remain with the old standard (1 ft=1200/3937 m) until further decision. This foot is named the U.S. survey foot. As a result, all U.S. land measurements in U.S. customary units will relate to the meter by the old standard. All the conversion factors in these tables for units referenced to this footnote are based on the U.S. survey foot, rather than the international foot. Conversion factors for the land measure given below may be determined from the following relationships:

1 league=3 miles (exactly)

1 rod=16½ ft (exactly)

1 chain=66 ft (exactly)

1 section=1 sq mile

1 township=36 sq miles
↑ ^2.0 ^2.1 ^2.2 ^2.3 ^2.4 ^2.5 This value was adopted in 1956. Some of the older International Tables use the value 1.055 04 E+03. The exact conversion factor is 1.055 055 852 62* E+03
↑ ^3.0 ^3.1 This sometimes is called the moment of inertia of a plane section about a specified axis.
↑ ^4.0 ^4.1 ^4.2 The exact conversion factor is 1.638 706 4*E−05.
↑ ^5.0 ^5.1 ^5.2 ^5.3 ^5.4 ^5.5 ^5.6 ^5.7 ^5.8 ^5.9 Defined (not measured) value. (This reference should be ref 13)
↑ Not the same dimensions as “millidarcy-foot.”
↑ Not the same as reservoir “perm.”
↑ The exact conversion factor is 4.535 923 7*E−01.
↑ The exact conversion factor is 4.448 615 260 5*E+00.
↑ ^10.0 ^10.1 ^10.2 ^10.3 ^10.4 ^10.5 ^10.6 ^10.7 Torque unit; see text discussion of “Torque and Bending Moment.”
↑ ^11.0 ^11.1 ^11.2 Torque divided by length; see text discussion of “Torque and Bending Moment.”
↑ Defined (not measured) value.

Recommended SI units and conversion factors: Difference between revisions

Latest revision as of 18:22, 26 February 2020

Contents

Space, time

Mass, amount of substance

Calorific value, heat, entropy, heat capacity

Temperature, pressure, vacuum

Density, specific volume, concentration, dosage

Facility throughput, capacity

Flow rate

Energy, work, power

Mechanics

Transport properties

Electricity, magnetism

Acoustic, light, radiation

References

See also

Category

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Recommended SI units and conversion factors: Difference between revisions

Latest revision as of 18:22, 26 February 2020

Space, time

Mass, amount of substance

Calorific value, heat, entropy, heat capacity

Temperature, pressure, vacuum

Density, specific volume, concentration, dosage

Facility throughput, capacity

Flow rate

Energy, work, power

Mechanics

Transport properties

Electricity, magnetism

Acoustic, light, radiation

References

See also

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