The numerical value of the units in the When You Know column are multiplied by the approximate unit conversion factor found in the Multiply By column to obtain a numerical value for the units listed in the To Find Column. For example:
| When You Know | Multiply By | To Find |
|---|---|---|
| 20 yd | 0.91 | approximately18.2 m |
Length
| Symbol | When You Know | Multiply By | To Find | Symbol |
|---|---|---|---|---|
| in | inch | 2.54 | centimeter | cm |
| ft | foot | 30.48 | centimeter | cm |
| yd | yard | 0.91 | meter | m |
| mi | mile | 1.61 | kilometer | km |
Area
| Symbol | When You Know | Multiply By | To Find | Symbol |
|---|---|---|---|---|
| in² | square inch | 6.45 | square centimeter | cm² |
| ft² | square foot | 0.09 | square meter | m² |
| yd² | square yard | 0.84 | square meter | m² |
| mi² | square mile | 2.59 | square kilometer | km² |
| acre | 0.41 | hectare | ha |
Mass (weight)
| Symbol | When You Know | Multiply By | To Find | Symbol |
|---|---|---|---|---|
| oz | ounce | 28.35 | gram | g |
| lb | pound | 0.45 | kilogram | kg |
| short ton (2000 lb) | 0.91 | metric ton | t |
Volume
| Symbol | When You Know | Multiply By | To Find | Symbol |
|---|---|---|---|---|
| tsp | teaspoon | 4.93 | milliliter | mL |
| Tbsp | tablespoon | 14.79 | milliliter | mL |
| in³ | cubic inch | 16.39 | milliliter | mL |
| fl oz | fluid ounce | 29.57 | milliliter | mL |
| c | cup | 0.24 | liter | L |
| pt | pint, liquid | 0.47 | liter | L |
| qt | quart, liquid | 0.95 | liter | L |
| gal | gallon | 3.79 | liter | L |
| ft³ | cubic foot | 0.03 | cubic meter | m³ |
| yd³ | cubic yard | 0.76 | cubic meter | m³ |
Temperature (exact)
| Symbol | When You Know | Calculation | To Find | Symbol |
|---|---|---|---|---|
| °F | degree Fahrenheit | subtract 32,then divide by 1.8 | degree Celsius | °C |
| °F | degree Fahrenheit | subtract 32, divide by 1.8, add 273.15 | Kelvin | K |
Metric to U.S. Customary Conversions
Unit conversion is a multi-step process that involves multiplication or division by a numerical factor; selection of the correct number of significant digits; and rounding. Accurate unit conversions are obtained by selecting an appropriate conversion factor (a ratio which converts one unit of measure into another without changing the quantity).
Note: These approximate approximate conversion factors are published as NIST SP 365, which is a laminated metric conversion card. Copies of this publication can be requested by contacting theSI [at] nist.gov (theSI[at]nist[dot]gov)
