Common Engineering Unit Conversions

Common Engineering Unit Conversions - Basic Units Parameter (Basic Units) mass (m) length - distance (L) time (t)

SI Units kilogram (kg)

English/American Units pound mass (lbm)

meter (m)

foot or inch (ft or in) second (s)

current (I)

Ampere (A)

Derived Units Parameter (Derived Units) Force - weight (F or W) Torque (T) Work - energy (W or E) Power (P) Voltage, EMF (V) Resistance (R) Inertia (J) plane angle (α, β, γ, etc.) rotation (Ө) velocity - linear (v) acceleration (a) velocity - angular (ω)

SI Units Newton (N)

English/American Units pound or ounce (lbf or oz)

Newton-meter (Nm) Joule (J)

foot-pound (ft-lb or in-lb) foot-pound (ft-lb or in-lb

Watt (W)

horsepower (hp or W) Volt (V) ohms (Ω)

kilogram-meter2 (kg-m2) radian (rad)

inch-pound-second2 (in-lb-s2) degree or radian (deg or rad) revolution (rev)

meter per sec. (m/s)

inch per second (in/s)

meter per second2 (m/s2) inch per second2 (in/s2) rad per second (rad/s)

velocity - rotational (ω) accel - angular (α)

rev per minute (rpm) rad per second2 (rad/s2)

Basic Definitions & Formulae Parameter Formula Force - accel (F = m * a) Torque - accel (T = J * α) Voltage, EMF (V = I * R) Work - Energy (E = F * L) Energy - elect (E = V * I * t) Power (P = F * v) Power (P = T * ω)

SI Units Formula

English/American Units Formula 2

1 N = 1 kg * 1 m / s 1 Nm = 1 kg-m2 * 1 rad / s2 1J=1N*1m

1 lbf = 1 lbf / (386 in / s2) * 386 in / s2 1 in-lb = 1 in-bl-s2 * 1 rad / s2 1V=1A*1Ω

1 in-lb = .113 Nm = .113 Ws = .113 J 1J=1V*1A*1s

1W=1N*1m/s 1 W = 1 Nm * 1 rad / s

1 hp = 550 ft-lb / s = 745.7 W (note: radians have no units)

Power (P = V * I) Power (P = E / t)

1W=1V*1A 1W=1J/1s

Power (P = I2 * R)

1 W = 1 A2 * 1 Ω

Motor Constants Parameter Formula Torque const (Kt = T / I)

SI Units Formula Kt = Nm / A

English/American Units Formula Kt = in-lb / A

Voltage const (Ke = V / ω)

Ke = V / (rad / s)

Ke = V / krpm

SI Units Formula 1 A = 1 Nm / (Nm / A)

English/American Units Formula 1 A = 1 in-lb / (in-lb / A)

1 V = AΩ + V / (rad / s) * (rad / s)

1 V = AΩ + V / (krpm) * (krpm)

Servo Motor Formulae Parameter Formula Current Draw (I + T / Kt) Voltage Required (V = IRa + Ke * ω)

Conversions:

To convert from units of A to units of B, find the value at the intersection of A and B, then multiply your number by this value. Example: to convert from cm to microns, multiply value in cm by 1.00E+04.

Length Conversion A (below) B (right)

micron (µm)

mm

cm

m

in

ft

micron (µm) mm

1 1000

0.001 1

1.00E-04 0.1

1.00E-06 0.001

3.94E-05 0.03937

3.28E-06 3.28E-03

cm m in

1.00E+04 1.00E+06 2.54E+04

10 1000 25.4

1 100 2.54

0.01 1 0.0254

0.3937 39.37 1

0.03281 3.281 0.0833

ft

3.05E+05

304.8

30.48

0.3048

12

1

Mass Conversion A (below) B (right)

g

kg

slug

ozm

lbm

1 1000

0.001 1

6.85E-05 6.85E-02

0.0353 35.274

2.20E-03 2.2046

slug ozm

1.46E+04 28.35

14.59 0.0284

1 1.94E-03

514.78 1

32.17 0.0625

lbm

453.6

0.4536

0.0311

16

1

N

kgf

gf

ozf

lbf

N kgf

1 9.81

0.102 1

101.97 1000

3.596 35.274

0.225 2.205

gf ozf lbf

9.81E-03 0.28 4.45

0.001 0.0283 0.4536

1 28.35 453.6

0.0353 1 16

2.21E-03 0.0625 1

g kg

Force Conversion A (below) B (right)

Torque Conversion A (below) B (right) g-cm

g-cm

kg-cm

kg-m

N-m

oz-in

lb-in

lb-ft

1

0.001

1.00E-05

9.81E-05

0.014

8.68E-04

7.23E-05

kg-cm kg-m

1000 1.00E+05

1 100

0.01 1

0.098 9.81

13.89 1389

0.868 86.8

0.072 7.23

N-m oz-in

1.02E+04 72.01

10.2 0.072

0.102 7.21E-04

1 7.06E-03

141.6 1

8.85 0.063

0.738 5.21E-03

lb-in lb-ft

1.15E+03 1.38E+04

1.152 13.83

0.012 0.138

0.113 1.356

16 192

1 12

0.083 1

Power Conversion A (below) B (right) Watts

Watts

kW

Horsepower

in-lb/s

ft-lb/s

1

100E-03

1.34E-03

8.85

0.74

kW Horsepower in-lb/s

1000 746 0.113

1 0.746 1.13E-04

1.34 1 1.52E-04

8851 6600 1

738 550 0.083

ft-lb/s

1.35

1.36E-03

1.82E-03

12

1

Linear Velocity Conversion A (below) B (right)

mm/s

cm/s

m/s

in/s

ft/s

in/min

ft/min

mm/s cm/s

1 10

0.1 1

0.001 0.01

0.0394 0.394

3.28E-03 0.0328

2.362 23.62

0.1968 1.97

m/s in/s

1000 25.4

100 2.54

1 0.0254

39.37 1

3.281 0.083

2362.2 60

196.9 5

ft/s in/min ft/min

304.8 0.423 5.08

30.48 0.0423 0.508

0.3048 4.23E-04 5.08E-03

12 0.0167 0.2

1 1.39E-03 0.0167

720 1 12

60 0.0833 1

Angular Velocity Conversion A (below) B (right) deg/s rad/s rpm rps

deg/s 1 57.3

rad/s 0.0175 1

rpm 0.167 9.55

rps 2.78E-03 0.159

6 360

0.105 6.28

1 60

0.0167 1

Rotary Inertia Conversion A (below) B (right)

g-cm2

kg-cm2

g-cm-s2

g-cm2

1

0.001

0.001

kg-cm2

1000

1

1.02

0.001

0.981

1

0.001

981

1000

1

10000

10190

g-cm981 s2 kg-cm9.81E+05 s2 kg-m2 1.00E+07

kg-cm-s2

kg-m2

lb-in-s2

lb-ft-s2

lb-in2

lb-ft2

oz-in2

oz-ins2

8.85E-04 7.38E-05

0.342

2.40E-03

5.47

1.42E05 0.014

9.81E-05 8.68E-04 7.23E-05

0.335

2.30E-03

5.36

0.014

1.02E-06 1.00E-07 8.85E-07 7.38E-08 3.42E-04 2.37E-06 5.50E-03 0.0001

0.0981

0.868

0.072

335.1

2.33

5362

13.89

54675

141.6

10.19

1

8.85

0.738

3417.74

23.734

lb-in-s2 1.13E+06 1130 1.15E+03 lb-ft-s2 1.36E+07 1.36E+04 1.38E+04

1.152 13.83

0.113 1.36

1 12

0.083 1

386.1 4633

2.68 32.2

lb-in2 lb-ft2

2926 4.21E+05

2.93 421.4

2.98 429.7

0.003 0.43

1 144

6.90E-03 1

16 2304

0.041 5.97

oz-in2

182.9

0.183

0.187

0.0625

4.34E-04

1

2.60E03

70.62

72

24.13

0.168

386.1

1

oz-in-s2 7.06E+04

2.93E-04 2.60E-03 2.16E-04 0.0421 0.373 0.031

1.87E-04 1.83E-05 1.62E-04 1.35E-05 0.072

0.007

0.063

5.20E-03

6177 16 7.41E+04 192