The Cup Problem: Three Cups, Three Sizes
If you're converting an American recipe for a European kitchen, or following an Australian recipe in a US kitchen, you've likely hit the cup problem. "Cup" sounds universal — but there are actually three different cup sizes in common culinary use worldwide:
- US customary cup = 236.588 mL (≈ 237 mL)
- Metric cup (Australia, Canada, South Africa) = 250 mL exactly
- UK/Imperial cup (now rarely used in recipes) ≈ 284 mL
The difference between a US cup (237 mL) and a metric cup (250 mL) is about 5.4%. For most cooking that's negligible, but for baking — especially cakes, custards, and bread — it can push a recipe outside its working range. This guide gives you the exact values and a complete reference table to use when converting between cups and milliliters.
Exact Conversions: US Cup to mL
The US customary cup is defined as exactly 8 US fluid ounces. One US fluid ounce = 29.5735 mL, so:
1 US cup = 8 × 29.5735 = 236.588 mL
For practical purposes, 1 US cup ≈ 240 mL (a common kitchen simplification used in many cookbooks — close enough for most recipes, with only 1.4% error).
Complete US Cup Fractions to Milliliter Table
| US Measurement | Milliliters (exact) | Milliliters (rounded) |
|---|---|---|
| 1 teaspoon (tsp) | 4.929 mL | 5 mL |
| 1 tablespoon (tbsp) | 14.787 mL | 15 mL |
| ⅛ cup | 29.574 mL | 30 mL |
| ¼ cup | 59.147 mL | 60 mL |
| ⅓ cup | 78.863 mL | 80 mL |
| ½ cup | 118.294 mL | 120 mL |
| ⅔ cup | 157.725 mL | 160 mL |
| ¾ cup | 177.441 mL | 180 mL |
| 1 cup | 236.588 mL | 240 mL |
| 1½ cups | 354.882 mL | 355 mL |
| 2 cups | 473.176 mL | 475 mL |
| 4 cups (1 quart) | 946.353 mL | 946 mL (~1 L) |
Metric Cup vs US Cup: The Difference Matters in Baking
Australian, New Zealand, and Canadian recipe sites default to the metric cup (250 mL exactly). If you're in the US and following an Australian recipe with "1 cup," you're short by about 13.5 mL (250 − 236.6 = 13.4 mL) per cup. In a cake that calls for 3 cups of flour, that's about 40 mL short — roughly ⅛ cup. In bread and delicate cakes, this can matter significantly. The safest solution: convert cup quantities to grams using a reference table, then weigh on a scale.
Tablespoons and Teaspoons to Milliliters
The US tablespoon and teaspoon have exact definitions: 1 tablespoon = 3 teaspoons = ½ fluid ounce = 14.787 mL. For most purposes, 1 tablespoon ≈ 15 mL and 1 teaspoon ≈ 5 mL. Many metric recipes already use 15 mL and 5 mL measures directly, so this simplification is widely accepted and causes no practical baking error.
When Volume Measurements Fail: The Density Problem
Volume measurements (cups) work reasonably well for liquids — water, milk, oil. They break down badly for dry ingredients because density varies. Consider: 1 cup of all-purpose flour can range from 120 g (lightly spooned and leveled) to 165 g (directly scooped from the bag). That's a 37% range. 1 cup of brown sugar (loosely packed) can range from 180–220 g. For professional-level baking consistency, weigh dry ingredients in grams and use cup/mL measures only for liquids. Use our weight converter to cross-check any value.
Practical Tips for Recipe Conversion
When converting a US recipe for a metric kitchen (or vice versa): first, identify which cup standard the original recipe uses (US, Australian/metric, or UK). If the recipe is from an American cookbook or website, assume US cups (237 mL). Then convert cup quantities to milliliters using the table above, rounding to the nearest 5 mL for liquids. For flour, sugar, and other dry ingredients, weigh in grams instead — the weight table in our grams to ounces article is your best reference.
Frequently Asked Questions
How many mL are in a US cup?
A US customary cup equals exactly 236.588 mL, typically rounded to 237 mL. The US cup is defined as 8 US fluid ounces, and 1 US fluid ounce = 29.5735 mL. This is the cup standard used in American cookbooks and measuring tools sold in the US.
Is a metric cup the same as a US cup?
No. A metric cup equals exactly 250 mL, while a US cup is 237 mL — a difference of about 13 mL (5.5%). Australian and Canadian recipes typically use metric cups (250 mL). If a recipe doesn't specify, check the origin: American cookbooks use 237 mL, while Australian or metric recipes use 250 mL.
How do I convert 1/4 cup to milliliters?
1/4 US cup = 59.15 mL (≈ 60 mL). Fractions: 1/8 cup = 29.6 mL, 1/4 cup = 59.1 mL, 1/3 cup = 78.9 mL, 1/2 cup = 118.3 mL, 3/4 cup = 177.4 mL, 1 cup = 236.6 mL. For metric cups (250 mL): 1/4 cup = 62.5 mL, 1/2 cup = 125 mL.