Length 1 in = 2.54 cm (Exact) 1 ft = 12 in (Exact) 1 yd = 3 ft (Exact) 1 mi = 5,280 ft (Exact) Area 1 acre = 4,840 yd^{2}(Exact) Volume 1 cc = 1 cm^{3}= 1 mL (Definition) 1 mL = 20 drop (metric) (Exact) 1 gal = 231 in^{3}(Exact) 1 gal = 4 qt (Exact) 1 qt = 2 pint (Exact) 1 pint = 2 cup (Exact) 1 gal = 128 floz (Exact) 1 floz = 2 tbsp (Exact) 3 tsp = 1 tbsp (Exact) Time 1 s = the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom. min = 60 s (Exact) h = 60 min (Exact) d = 24 h (Exact) yr = y = 365 d a = 365.25 d (Julian year - astronomy) Mass 1 lbm = 453.6 gm 16 oz = 1 lbm (Exact) 1 slug = 1 lbf-s^{2}/ft (Definition) 1 lbf-s^{2}/in = 175.1 kg Force 1 lbf == 1 lbm on earth (Definition) 1 N = 1 kg-m/s^{2}(Definition) 1 dyn = 1 gm-cm/s^{2}(Definition) 1 N = 10^{5}dyn (1 dyn = 10 µN) 1 lbf = 4.448 N 1 ton = 2,000 lbf (Exact) 1 kip = 1,000 lbf (Exact) Pressure 1 Pa = 1 N/m^{2}(Definition) 1 atm = 101,325 Pa (Exact) 1 bar = 100,000 Pa (Definition) 1 atm = 760 Torr (Exact) 1 Torr = 1 mmHg 1 psi = 1 lbf/in^{2}(Definition) 1 ksi = 1,000 psi (Definition) 1 atm = 14.7 psi Work-Energy 1 J = 1 N-m (Definition) 1 erg = 1 dyn-cm (Definition) 1 J = 8.8507 in-lbf Power 1 W = 1 J/s (Definition) 1 hp = 550 ft-lbf/s (Exact) Temperature 1°R = 5/9 K (Exact) (1 K is 1.8 times larger than 1 °R) [°F] = 9/5[°C] + 32 (Exact) [K] = [°C] + 273.15 (Exact) [R] = [°F] + 459.67 (Exact) Physical Constants 1g = 386.1 in/s^{2}1g = 9.81 m/s^{2}Pound-force Conversion (g_{c}F = ma) g_{c}= 32.174 lbm-ft/(lbf-s^{2})

y yocto 10^{-24}z zepto 10^{-21}a atto 10^{-18}f femto 10^{-15}p pico 10^{-12}n nano 10^{-9}µ micro 10^{-6}m milli 10^{-3}c centi 10^{-2}d deci 10^{-1}da deka 10^{1}h hecto 10^{2}k kilo 10^{3}M mega 10^{6}G giga 10^{9}T tera 10^{12}P peta 10^{15}E exa 10^{18}Z zetta 10^{21}Y yotta 10^{24}

1 mol = 6.022 141 79(30)×10^{23}N (SI base unit) 1 lbmol = lb-mol = 453.592 37 mol (12 lb of^{12}C) N_{A}= 6.022×10^{23}mol^{-1}N_{A}= 2.731 597×10^{26}lbmol^{-1}

M(air) = 28.97 g/mol = 1.654×10^{-4} lbf-s^{2}/(in-mol)
(Air is 78% N_{2})

M(N_{2}) = 2 M(N) = 2(14.007 g N)/(1 mol N) = 28.014 g/mol =
1.5996×10^{-4} lbf-s^{2}/(in-mol)

M(He) = 4.002602 g/mol = 2.285545×10^{-5} lbf-s^{2}/(in-mol)

Universal Gas ConstantR = 8.314462 N-m/(mol-K) = 3.406907 ft-lbf/(mol-°R) = 40.88288 in-lbf/(mol-°R)Specific Gas ConstantAir: R_{air}= 53.343 ft-lbf/(lbm-°R) = 247,142 in^{2}/(s^{2}-°R) N_{2}: R_{N2}= 55.163 ft-lbf/(lbm-°R) = 255,575 in^{2}/(s^{2}-°R) He: R_{He}= 386.086 ft-lbf/(lbm-°R) = 1,788,759 in^{2}/(s^{2}-°R) P V = Z m R_{specific}T

1 light-year = 9,460,730,472,580,800 m (Exact) ≈ 9.4607×10The light-year is based on a Julian year of 365.25 days and a speed of light of 299,792,458 m/s.^{15}m ≈ 5.8786×10^{12}mi ≈ 63.241×10^{3}AU (Astronmomical units) ≈ 0.3066 pc (parsecs)

1 lbm = 0.453 592 37 kg by definition (Wikipedia)

From F = ma: 1 lbf = m×g_{o} =
(0.45359237 kg/lbm)(9.80665 m/s^{2}) =
**4.448**2216152605 N (kg-m/s^{2})

From m = F/g_{o}: lb_{f}-s^{2}/in =
1 lb_{f}-s^{2}/in (in/.0254 m)
(lb_{m}⋅9.80665 m/lb_{f}⋅s^{2})
(.453 592 37 kg / lb_{m}) = **175.1**268 kg

1 Torr = 101,325/760 Pa 1 cmH2O = 98.0638 Pa 1 inH2O = 2.54 cmH2O 1 inHg = 3,386.389 Pa 1 mmHg = 13.5951(9.80665) Pa = 133.322387415 Pa 1 atm = 14.696 psi (Approximate)

1 BTU = 1,055.05585J (Approximate)A BTU is defined as amount of heat required to raise the temperature of one 1 pound (0.454 kg) of liquid water by 1 °F (0.556 °C) at a constant pressure of one atmosphere.

Specific gravity: s = ρ/ρ_{w}

Specific weight: γ = ρ⋅g

ρ_{w} = 1.00 gm/cm^{3} = 1000 kg/m^{3}

ρ_{w} = 1000 kg/m^{3}(lb_{f}-s^{2}/
175.1268 kg-in)(.0254 m/in)^{3} = 9.357×10^{-5}
lb_{f}-s^{2}/in^{4}

Specific gravity is based on the density of water at various temperatures
and depends on the industry using it. The American Petroleum Institute (API)
uses a 60°F water
density of 999.016
kg/m^{3}. In chemistry, aqueous solutions typically use a maximum
density (near 4°) of 999.972 kg/m^{3}.

ρ_{w} = 999.016(9.35725468740217772E-8) = 9.34804714878977398E-5
lb_{f}-s^{2}/in^{4}

ρ_{w} = 999.972(9.35725468740217772E-8) = 9.35699268427093046E-5
lb_{f}-s^{2}/in^{4}

γ_{w} = ρ_{w}⋅g =
1000 kg/m^{3}(9.80665 m/s^{2})
(lb_{f}-s^{2}/175.1268 kg⋅in)
(.0254 m/in)^{2})(12 in/ft)^{3} = 62.42796
lb_{f}/ft^{3}

1 P = 1 gm/cm-s (Poise)

1 Pl = 10 P

1 cP = 10^{-3} N-s/m^{2}

1 cP = (10^{-3} N-s/m^{2} / cP)(lb_{f} /
4.4482216152605 N)(.0254 m / in)^{2} =
1.450×10^{-7}
lb_{f}-s/in^{2}

1 St = 1 cm^{2}/s (Stoke)

1 cSt = 1 cs = 1 mm^{2}/s (centistoke)

1 cSt = 10^{-6} m^{2}/s

1 cSt = 10^{-6} m^{2}/s(in/.0254 m)^{2}
= .00155 in^{2}/s

SI Standard Abbreviations