Unit & Measurement Tables
Volume Conversion Table
Volume conversions have a trap that length and weight do not: the same word means different amounts depending on which side of the Atlantic it is printed on. A US gallon is 3.785 litres; an imperial gallon is 4.546 litres, 20% larger. A US cup is 236.6 mL; a metric cup is 250 mL. A US tablespoon is 14.79 mL; an Australian one is 20 mL. None of these are errors — they are separate legal standards.
The tables below use US liquid measure throughout, because that is what most online recipes and product labels assume, and they are built from the exact NIST Handbook 44 definitions rather than from rounded kitchen approximations. Where a metric equivalent is common enough to cause confusion, the note under the table says so.
If you are converting for cooking, the practical rule is to trust the unit on the recipe and convert only once. Converting cups to millilitres, then millilitres to fluid ounces, then back to cups is how a 236 mL cup quietly becomes 240 mL and a cake comes out dry.
Litres to US gallons, quarts, pints and cups
| Litres | US gallons | US quarts | US pints | US cups |
|---|---|---|---|---|
| 0.25 | 0.066 | 0.264 | 0.53 | 1.06 |
| 0.5 | 0.132 | 0.528 | 1.06 | 2.11 |
| 1 | 0.264 | 1.057 | 2.11 | 4.23 |
| 1.5 | 0.396 | 1.585 | 3.17 | 6.34 |
| 2 | 0.528 | 2.113 | 4.23 | 8.45 |
| 3 | 0.793 | 3.17 | 6.34 | 12.68 |
| 4 | 1.057 | 4.227 | 8.45 | 16.91 |
| 5 | 1.321 | 5.283 | 10.57 | 21.13 |
| 10 | 2.642 | 10.567 | 21.13 | 42.27 |
| 20 | 5.283 | 21.134 | 42.27 | 84.54 |
| 50 | 13.209 | 52.834 | 105.67 | 211.34 |
| 100 | 26.417 | 105.669 | 211.34 | 422.68 |
US liquid measures. A US gallon is 3.785 411 784 L; an imperial gallon is 4.546 09 L, about 20% larger.
US gallons to litres and millilitres
| US gallons | Litres | Millilitres | Imperial gallons |
|---|---|---|---|
| 0.5 | 1.893 | 1,893 | 0.416 |
| 1 | 3.785 | 3,785 | 0.833 |
| 2 | 7.571 | 7,571 | 1.665 |
| 3 | 11.356 | 11,356 | 2.498 |
| 4 | 15.142 | 15,142 | 3.331 |
| 5 | 18.927 | 18,927 | 4.163 |
| 10 | 37.854 | 37,854 | 8.327 |
| 15 | 56.781 | 56,781 | 12.49 |
| 20 | 75.708 | 75,708 | 16.653 |
| 25 | 94.635 | 94,635 | 20.817 |
| 50 | 189.271 | 189,271 | 41.634 |
| 100 | 378.541 | 378,541 | 83.267 |
Fuel economy in miles per US gallon and miles per imperial gallon differ by about 20% for this reason alone.
Millilitres to teaspoons, tablespoons, cups and fluid ounces
| Millilitres | Teaspoons | Tablespoons | US cups | US fl oz |
|---|---|---|---|---|
| 5 | 1.01 | 0.34 | 0.021 | 0.17 |
| 10 | 2.03 | 0.68 | 0.042 | 0.34 |
| 15 | 3.04 | 1.01 | 0.063 | 0.51 |
| 30 | 6.09 | 2.03 | 0.127 | 1.01 |
| 50 | 10.14 | 3.38 | 0.211 | 1.69 |
| 100 | 20.29 | 6.76 | 0.423 | 3.38 |
| 150 | 30.43 | 10.14 | 0.634 | 5.07 |
| 240 | 48.69 | 16.23 | 1.014 | 8.12 |
| 500 | 101.44 | 33.81 | 2.113 | 16.91 |
| 750 | 152.16 | 50.72 | 3.17 | 25.36 |
| 1,000 | 202.88 | 67.63 | 4.227 | 33.81 |
1 US teaspoon = 4.9289 mL, not 5 mL. The metric teaspoon used on Australian and UK packaging is exactly 5 mL.
How to Use These Tables
- Litres to US gallons: divide by 3.785 411 784. For a fast estimate, divide by 4 and add 5.4% back.
- Gallons to litres: multiply by 3.785 411 784. If the figure came from a UK source, multiply by 4.546 09 instead.
- For recipes, convert the whole batch once rather than each ingredient separately — rounding each ingredient compounds.
- Fluid ounces measure volume, not weight. A 12 fl oz can of soda is about 355 mL, but 12 oz of flour by weight is a very different amount.
Common Questions
How many litres are in a US gallon?
3.785 411 784 litres exactly, by NIST Handbook 44. The commonly used 3.785 is accurate to three decimals; the imperial gallon is 4.546 09 L.
Is 1 cup 250 mL or 240 mL?
A US customary cup is 236.588 mL, a US legal cup used on nutrition labels is 240 mL, and a metric cup is 250 mL. For baking, the 1–2% difference is usually invisible; for large batches it is not.
How many tablespoons are in a cup?
16 US tablespoons, because a US cup is 8 fl oz and a tablespoon is ½ fl oz. In Australia, where a tablespoon is 20 mL, a 250 mL cup holds 12.5 tablespoons.
Why is a fluid ounce not the same as an ounce?
A fluid ounce is a volume of 29.57 mL; an ounce is a mass of 28.35 g. They coincide only for water-like liquids, and even then only approximately — a fluid ounce of honey weighs about 42 g.
How do I convert a fuel economy figure in mpg to L/100 km?
Divide 235.215 by the miles per US gallon figure. For imperial gallons the constant is 282.481. The relationship is reciprocal, so doubling mpg halves L/100 km.
More Unit & Measurement Tables
Sources
- NIST Handbook 44 — Specifications, Tolerances and Other Technical Requirements for Weighing and Measuring Devices — National Institute of Standards and Technology
- NIST Special Publication 811 — Guide for the Use of the International System of Units — National Institute of Standards and Technology
- U.S. Code of Federal Regulations, Title 21, Part 101 — Food Labeling — U.S. Food and Drug Administration
Filed with Unit Conversion calculations.