Unit Conversions Reference
A quick reference for the unit conversions that come up most often in physics and chemistry. Values marked with ≈ are standard rounded approximations; everything else is exact by definition.
Length
| Unit | Equals |
|---|---|
| 1 kilometer | 1000 meters |
| 1 meter | 100 centimeters |
| 1 centimeter | 10 millimeters |
| 1 inch | 2.54 centimeters |
| 1 foot | 12 inches (30.48 centimeters) |
| 1 mile | ≈ 1.609 kilometers |
| 1 nanometer | 10-9 meters |
| 1 angstrom | 10-10 meters |
Mass
| Unit | Equals |
|---|---|
| 1 kilogram | 1000 grams |
| 1 gram | 1000 milligrams |
| 1 metric ton (tonne) | 1000 kilograms |
| 1 pound | ≈ 0.4536 kilograms |
| 1 atomic mass unit (u) | ≈ 1.66 × 10-27 kilograms |
Time
| Unit | Equals |
|---|---|
| 1 minute | 60 seconds |
| 1 hour | 60 minutes (3600 seconds) |
| 1 day | 24 hours (86,400 seconds) |
| 1 year (365 days) | ≈ 3.15 × 107 seconds |
Energy
| Unit | Equals |
|---|---|
| 1 calorie | 4.184 joules |
| 1 kilocalorie (food Calorie) | 4184 joules |
| 1 electronvolt (eV) | ≈ 1.602 × 10-19 joules |
| 1 kilowatt-hour (kWh) | 3.6 × 106 joules |
Common SI prefixes
| Prefix | Symbol | Factor |
|---|---|---|
| giga | G | 109 |
| mega | M | 106 |
| kilo | k | 103 |
| centi | c | 10-2 |
| milli | m | 10-3 |
| micro | µ | 10-6 |
| nano | n | 10-9 |
| pico | p | 10-12 |