US and imperial volumes are not the same
This is the most common source of ruined recipes. A US gallon is 3.785 liters while an imperial (UK) gallon is 4.546 liters — about 20% larger. The difference propagates through every subdivision: a US pint is 473 mL against an imperial pint's 568 mL, and a US fluid ounce is 29.57 mL against 28.41 mL.
Confusingly, the imperial fluid ounce is slightly smaller than the US one even though the imperial pint is larger, because an imperial pint contains 20 fluid ounces while a US pint contains 16. This converter uses US customary units throughout.
| Measure | US | Imperial (UK) | Metric | Notes |
|---|---|---|---|---|
| Fluid ounce | 29.57 mL | 28.41 mL | — | US is 4% larger |
| Cup | 236.6 mL | 284.1 mL (10 imp fl oz) | 250 mL (Australia, NZ) | Three different cups |
| Pint | 473.2 mL (16 fl oz) | 568.3 mL (20 fl oz) | — | Imperial pint is 20% larger |
| Quart | 946.4 mL | 1,136.5 mL | — | |
| Gallon | 3.785 L | 4.546 L | — | Imperial gallon is 20% larger |
Cooking measures
US kitchen volumes relate to each other in simple ratios.
- 1 tablespoon = 3 teaspoons = 14.79 mL
- 1 fluid ounce = 2 tablespoons = 29.57 mL
- 1 cup = 8 fl oz = 16 tablespoons = 236.6 mL
- 1 pint = 2 cups = 473.2 mL
- 1 quart = 2 pints = 4 cups = 946.4 mL
- 1 gallon = 4 quarts = 16 cups = 3.785 L
| Unit | Millilitres | Equals | In fluid ounces |
|---|---|---|---|
| Teaspoon (tsp) | 4.93 mL | ⅓ tbsp | — |
| Tablespoon (tbsp) | 14.79 mL | 3 tsp | ½ fl oz |
| Fluid ounce (fl oz) | 29.57 mL | 2 tbsp | ⅛ cup |
| Cup | 236.59 mL | 16 tbsp | 8 fl oz |
| Pint (pt) | 473.18 mL | 2 cups | 16 fl oz |
| Quart (qt) | 946.35 mL | 2 pt | 32 fl oz |
| Gallon (gal) | 3.785 L | 4 qt | 128 fl oz |
Why weight beats volume for baking
Volume measures the space an ingredient occupies, which for anything compressible is unreliable. A cup of flour can weigh anywhere from 120 to 150 grams depending on whether it was scooped, spooned, or sifted — a swing of 25% that visibly changes a bread or cake.
This is why professional and published baking recipes increasingly give weights. A kitchen scale removes the ambiguity entirely and is faster in practice, since you can add ingredients to one bowl on a tare. Liquids are far less affected, so volume remains fine for water, milk, and oil.
| Ingredient | Grams per cup | Density (g/mL) |
|---|---|---|
| Water | 237 g | 1.00 |
| Milk | 244 g | 1.03 |
| All-purpose flour, spooned | 120 g | 0.51 |
| Bread flour | 127 g | 0.54 |
| Granulated sugar | 200 g | 0.85 |
| Brown sugar, packed | 220 g | 0.93 |
| Powdered sugar | 120 g | 0.51 |
| Butter | 227 g | 0.96 |
| Honey | 340 g | 1.44 |
| Vegetable oil | 218 g | 0.92 |
| Rolled oats | 90 g | 0.38 |
| Uncooked white rice | 185 g | 0.78 |
| Cocoa powder | 85 g | 0.36 |
| Chocolate chips | 170 g | 0.72 |
Volume versus weight ounces
The word ounce refers to two different quantities, and recipes rarely disambiguate. A fluid ounce measures volume; an ounce measures weight. They coincide only for water, where one fluid ounce weighs almost exactly one ounce — the historical origin of the shared name.
For anything denser or lighter than water the two diverge. Eight fluid ounces of honey weighs about 12 ounces; eight fluid ounces of flour weighs about 4.5. When a recipe says ounces, liquids are usually fluid ounces and dry ingredients are usually weight, but if the result matters, checking is worthwhile.
Cups to millilitres
Scaling a recipe up or down is where fractions of a cup meet millilitres. One US cup is 236.6 mL; nutrition labels round it to 240.
| Cups | mL | tbsp | fl oz |
|---|---|---|---|
| ¼ cup | 59 | 4 | 2 |
| ⅓ cup | 79 | 5 | 2.7 |
| ½ cup | 118 | 8 | 4 |
| ⅔ cup | 158 | 11 | 5.3 |
| ¾ cup | 177 | 12 | 6 |
| 1 cup | 237 | 16 | 8 |
| 1½ cups | 355 | 24 | 12 |
| 2 cups | 473 | 32 | 16 |
| 3 cups | 710 | 48 | 24 |
| 4 cups (1 quart) | 946 | 64 | 32 |