Everyday unit converter
Feet and inches, ounces, Fahrenheit and gallons still turn up in recipes, manuals and conversation. Each converter below shows the answer in every unit of its family at once.
Length
Weight (mass)
Volume
Temperature
Values checked 26 October 2026. Next review due 26 October 2027.
This page is past its review date (26 October 2027). Official values can change, so check the linked sources before relying on these figures.
Metric prefixes in one line
Kilo means a thousand, centi a hundredth and milli a thousandth, so a kilometre is 1000 metres and a millilitre is a thousandth of a litre. Source: National Institute of Standards and Technology (NIST), Metric (SI) prefixes, checked 26 October 2026.
Inches, feet, yards and miles
Since the inch was fixed at exactly 2.54 centimetres, every imperial length converts exactly: a foot is 0.3048 metre, a yard 0.9144 metre and a mile 1609.344 metres. Source: National Institute of Standards and Technology (NIST), NIST Guide to the SI, Appendix B.8: Factors for units listed alphabetically (SP 811), checked 26 October 2026.
| Unit | Equals | Factor |
|---|---|---|
| Millimetre | 0.001 m | Exact |
| Centimetre | 0.01 m | Exact |
| Metre | 1 m | Exact |
| Kilometre | 1,000 m | Exact |
| Inch | 0.0254 m | Exact |
| Foot | 0.3048 m | Exact |
| Yard | 0.9144 m | Exact |
| Mile | 1,609.344 m | Exact |
Ounces and pounds
The ounce and pound here are the avoirdupois units used for groceries and body weight. The troy ounce used for gold is heavier; it is on the gold page. A fluid ounce is a volume, not a weight.
| Unit | Equals | Factor |
|---|---|---|
| Milligram | 0.000001 kg | Exact |
| Gram | 0.001 kg | Exact |
| Kilogram | 1 kg | Exact |
| Tonne (metric ton) | 1,000 kg | Exact |
| Ounce (avoirdupois) | 0.02834952 kg | Rounded by NIST |
| Pound (avoirdupois) | 0.4535924 kg | Rounded by NIST |
US and UK gallons are different
A US gallon is about 3.785 litres; the UK (imperial) gallon is exactly 4.546 09 litres, about a fifth larger. US cups, pints and quarts follow the US gallon. Source: National Institute of Standards and Technology (NIST), NIST Guide to the SI, Appendix B.8: Factors for units listed alphabetically (SP 811), checked 26 October 2026. The 5 ml teaspoon, 15 ml tablespoon and 240 ml cup are the US nutrition-labelling definitions. Source: U.S. Food and Drug Administration regulation (text via Cornell Law School LII), 21 CFR 101.9(b)(5)(viii), nutrition labeling household measures, checked 26 October 2026. The 250 ml cup is listed by its label only: we have not found an official definition of a 250 ml metric cup.
| Unit | Equals | Factor |
|---|---|---|
| Millilitre | 0.001 L | Exact |
| Litre | 1 L | Exact |
| Cubic metre | 1,000 L | Exact |
| Teaspoon, 5 ml | 0.005 L | Exact |
| Tablespoon, 15 ml | 0.015 L | Exact |
| Cup, 250 ml (metric cup) | 0.25 L | Exact |
| Cup, 240 ml (US labelling cup) | 0.24 L | Exact |
| Cup (US customary) | 0.2365882 L | Rounded by NIST |
| Tablespoon (US customary) | 0.01478676 L | Rounded by NIST |
| Teaspoon (US customary) | 0.004928922 L | Rounded by NIST |
| Fluid ounce (US) | 0.02957353 L | Rounded by NIST |
| Pint (US liquid) | 0.4731765 L | Rounded by NIST |
| Quart (US liquid) | 0.9463529 L | Rounded by NIST |
| Gallon (US) | 3.785412 L | Rounded by NIST |
| Gallon (UK, imperial) | 4.54609 L | Exact |
Celsius, Fahrenheit and kelvin
To turn Fahrenheit into Celsius, subtract 32 and divide by 1.8. To turn Celsius into kelvin, add 273.15. Source: National Institute of Standards and Technology (NIST), NIST Guide to the SI, Appendix B.8: Factors for units listed alphabetically (SP 811), checked 26 October 2026.
| Celsius | Fahrenheit | Kelvin |
|---|---|---|
| -40 °C | -40 °F | 233.15 K |
| 0 °C | 32 °F | 273.15 K |
| 37 °C | 98.6 °F | 310.15 K |
| 100 °C | 212 °F | 373.15 K |
| 180 °C | 356 °F | 453.15 K |
Sources for this page
- NIST Guide to the SI, Appendix B.8: Factors for units listed alphabetically (SP 811) — National Institute of Standards and Technology (NIST). Conversion factors; factors printed in bold on that page are exact, the rest are rounded by NIST. Checked 26 October 2026.
- Metric (SI) prefixes — National Institute of Standards and Technology (NIST). kilo = 1000, centi = one hundredth, milli = one thousandth. Checked 26 October 2026.
- 21 CFR 101.9(b)(5)(viii), nutrition labeling household measures — U.S. Food and Drug Administration regulation (text via Cornell Law School LII). For nutrition labeling, a teaspoon means 5 mL, a tablespoon 15 mL and a cup 240 mL. Checked 26 October 2026.