2/3 Cup to mL
Exactly how many milliliters are in 2/3 cup? 2/3 US cup = 157.73 mL, with a quick reference table for other common cup fractions.
2/3 Cup to mL: The Quick Answer
2/3 cup converts to 157.73 mL. Whether you are reading a metric label, a recipe, or an international spec, knowing how to convert 2/3 cup keeps your numbers consistent. Use our us cups to ml converter for any value, or read on for the full breakdown of the 157.73 mL result.
The Exact US Cups to Milliliters Formula
A US cup is 236.588 mL. To convert cups to milliliters, multiply the cups by 236.588. Two-thirds of a cup is (2 / 3) x 236.588.
Step-by-Step Calculation
Start with 2/3 cup. Multiply: (2 / 3) x 236.588 = 157.725 mL, which rounds to 157.73 mL.
A Quick Mental Estimate
Since 1 cup is about 237 mL, 2/3 cup is about two-thirds of that, roughly 158 mL.
Where 2/3 cup Comes Up
Two-thirds of a cup is a common baking measure for milk, water, or oil in US recipes, but metric recipes and scales work in milliliters. Knowing it is 157.73 mL lets you weigh or pour on a metric scale.
2/3 cup Compared With Nearby Values
Nearby cup amounts: 0.5 cup = 118.29 mL, 0.75 cup = 177.44 mL.
On the other side, 1 cup = 236.59 mL, 1.5 cup = 354.88 mL. Each step moves the figure smoothly, so the same formula scales to any amount.
Practical Uses of the 2/3 cup Conversion
Use this when a US recipe calls for 2/3 cup of liquid and your tools are metric. Our US cups to mL converter converts any cup fraction, and mL to cups converts milliliters back to cups.
Frequently Asked Questions
How many mL is 2/3 cup?
0.667 cup × 236.588 = 157.73 mL.
How many mL is 1/3 cup?
0.333 cup × 236.588 = 78.83 mL.
How many mL is 3/4 cup?
0.75 cup × 236.588 = 177.44 mL.
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Quick Summary
2/3 cup equals 157.73 mL. Use the us cups to milliliters relationship shown above for exact, repeatable results.
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US Cups to ML: Complete Baking and Cooking Conversion Guide
Convert US cups to milliliters for baking and cooking. Master the cups to ml conversion for accurate recipe measurements in metric.
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Disclaimer
Unit conversions on this site use internationally recognized, fixed conversion factors (for example, 1 inch = 2.54 cm, 1 pound = 0.45359237 kg, 1 °F = (°C × 9/5) + 32). They are provided for general, informational, and educational use. For applications where accuracy is critical — such as medical dosing, engineering, scientific research, trade, or legal compliance — always verify results against authoritative sources such as the U.S. National Institute of Standards and Technology (NIST) and the official International System of Units (SI) brochure, and follow any applicable local standards.
Exact Constants & Authoritative Sources
Every conversion on this page uses the fixed, internationally agreed constants below — drawn from NIST and the SI Brochure. No values are estimated or rounded as if exact. See the full list on our Sources & Standards page.
- EXACT1 US gallon (gal) = 3.785411784 litres (exact, 231 in³)
- EXACT1 US fluid ounce (fl oz) = 29.5735295625 mL (exact, 1/128 gal)
- EXACT1 US cup = 236.5882365 mL (exact, 8 fl oz)
- EXACT1 US pint (pt) = 473.176473 mL (exact, 16 fl oz)
- EXACT1 US quart (qt) = 946.352946 mL (exact, 32 fl oz)
- EXACT1 litre (L) = 1000 millilitres (definition)
Common Pitfalls & How to Avoid Them
US vs. Imperial (UK) cups
A US cup is 236.59 mL, but a UK/metric cup is 250 mL and an Imperial cup is ~284 mL. Recipes from different countries are not interchangeable drop-in.
Fluid ounce is volume, not mass
A US fl oz is 29.57 mL of volume. 1 fl oz of water ≈ 29.57 g, but 1 fl oz of honey or oil weighs more. Do not treat fluid ounces as grams.
Teaspoon/tablespoon sizes differ
1 US tbsp = 14.7868 mL; 1 US tsp = 4.92892 mL. Metric measuring spoons are 15 mL and 5 mL — close but not exact; for baking precision use weighed grams.
A unit-conversion reference site has no manufacturer-specific or device calibration parameters, so "layered tuning" does not apply here. The only real error-handling is input validation: the converter rejects non-numeric, empty, or out-of-range entries and shows a clear message, then falls back to exact constants above. No estimated or rounded figures are ever presented as exact.
Authoritative sources for this page
- NIST (U.S. National Institute of Standards and Technology) — NIST SP 330 — The International System of Units (SI), 2019 edition
- BIPM (International Bureau of Weights and Measures) — SI Brochure — The International System of Units (9th edition)
Last Updated 2026 | This article was reviewed for accuracy