Scientific units of measurement
30 units from this system across 13 categories, 10 of them historical or traditional.
Length
| Unit | Symbol | Value in meters |
|---|---|---|
| femtometer | fm | 1×10⁻¹⁵ m |
| angstrom | Å | 1×10⁻¹⁰ m |
Weight & Mass
| Unit | Symbol | Value in kilograms |
|---|---|---|
| dalton | Da | ≈ 1.660539069×10⁻²⁷ kg |
Volume
| Unit | Symbol | Value in liters |
|---|---|---|
| cubic kilometer | km³ | 1,000,000,000,000 L |
Area
| Unit | Symbol | Value in square meters |
|---|---|---|
| barn | b | 1×10⁻²⁸ m² |
Temperature
| Unit | Symbol | Value in kelvins |
|---|---|---|
| degree Rankine | °R | 0.5555555556 K |
| degree Newton | °N | — |
Time
| Unit | Symbol | Value in seconds |
|---|---|---|
| picosecond | ps | 1×10⁻¹² s |
| shake | shake | 1×10⁻⁸ s |
Speed
| Unit | Symbol | Value in meters per second |
|---|---|---|
| Mach | Ma | ≈ 340.294 m/s |
| speed of light | c | 299,792,458 m/s |
| kilometer per second | km/s | 1,000 m/s |
Energy
| Unit | Symbol | Value in joules |
|---|---|---|
| calorie | cal | 4.184 J |
| kilocalorie | kcal | 4,184 J |
| electronvolt | eV | 1.602176634×10⁻¹⁹ J |
| kiloelectronvolt | keV | 1.602176634×10⁻¹⁶ J |
| megaelectronvolt | MeV | 1.602176634×10⁻¹³ J |
| gigaelectronvolt | GeV | 1.602176634×10⁻¹⁰ J |
| calorie (IT) | cal (IT) | 4.1868 J |
| liter-atmosphere | L⋅atm | 101.325 J |
| ton of TNT | tTNT | 4,184,000,000 J |
Power
| Unit | Symbol | Value in watts |
|---|---|---|
| kilocalorie per hour | kcal/h | 1.162222222 W |
| calorie per second | cal/s | 4.184 W |
Pressure
| Unit | Symbol | Value in pascals |
|---|---|---|
| torr | Torr | 133.3223684 Pa |
| millimeter of mercury | mmHg | 133.3223874 Pa |
| millimeter of water | mmH₂O | 9.80665 Pa |
Angle
| Unit | Symbol | Value in turns |
|---|---|---|
| milliradian | mrad | 0.0001591549431 turn |
Frequency
| Unit | Symbol | Value in hertz |
|---|---|---|
| radian per second | rad/s | 0.1591549431 Hz |
| degree per second | °/s | 0.002777777778 Hz |
Counting & Quantity
| Unit | Symbol | Value in pieces |
|---|---|---|
| mole | mol | 6.02214076×10²³ pc |