How many fluid ounces in a cup?

By Paulo de VriesLast verified 2026-05-214 sources~4 min readhigh consensus

1 US cup = 8 fluid ounces (fl oz). 1 fl oz = 1/8 cup. Common: 4 fl oz = 1/2 cup, 16 fl oz = 2 cups (1 pint), 32 fl oz = 1 quart, 128 fl oz = 1 gallon. Note: US fluid oz ≠ UK fluid oz (28.4 mL ≠ 29.6 mL).

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The full answer

The conversion (always the same)

1 US cup = 8 US fluid ounces. The US fluid ounce = 29.5735 mL. The US cup = 236.59 mL (8 × 29.57).

Quick reference table

Fluid ounces	Cups	Pints	Milliliters
1 fl oz	1/8 cup	1/16 pint	29.6 mL
2 fl oz	1/4 cup	1/8 pint	59.1 mL
4 fl oz	1/2 cup	1/4 pint	118.3 mL
6 fl oz	3/4 cup	3/8 pint	177.4 mL
8 fl oz	1 cup	1/2 pint	236.6 mL
16 fl oz	2 cups	1 pint	473.2 mL
32 fl oz	4 cups	2 pints (1 qt)	946.4 mL
128 fl oz	16 cups	8 pints (1 gal)	3,785 mL (≈ 3.79 L)

US fluid oz vs UK fluid oz (where confusion happens)

Standard	Fluid ounce (mL)	Cup (mL)	Pint (mL)
US customary	29.57	236.6 (8 fl oz)	473.2 (16 fl oz)
US legal (FDA nutrition labels)	30 (exact)	240 (8 fl oz × 30)	480
UK imperial	28.41	284.1 (10 fl oz)	568.3 (20 fl oz)

US imperial: 1 UK pint = 20 fl oz; US pint = 16 fl oz. UK fl oz = 28.4 mL; US fl oz = 29.57 mL. A "pint" in a US recipe ≠ a "pint" in a UK recipe.

Weight vs volume ounce (do NOT confuse)

1 weight ounce (oz) = 28.35 grams. 1 fluid ounce (fl oz) = 29.57 mL (US) or 28.41 mL (UK).

For WATER specifically, they happen to be close (1 fl oz water ≈ 1 weight oz water at 4°C). For other ingredients, weight and volume diverge significantly. Always check whether your recipe specifies "oz" by weight or "fl oz" by volume.

Common cooking scenarios

"8 fl oz milk" → 1 cup = 240 mL (close enough)
"12 fl oz beer" → 1.5 cups (one standard beer bottle)
"16 fl oz can of broth" → 2 cups (one US standard can)
"32 fl oz quart of stock" → 4 cups
"1/2 gallon (64 fl oz) milk" → 8 cups

Why this conversion shows up so often

US recipe books and supermarket packaging frequently mix cup and fl oz units in the same recipe ("1 cup milk + 4 fl oz cream"). They are the same measurement system (volume), so swapping is mechanical: 1 cup = 8 fl oz. Just remember to halve, double, or convert directly.

Cross-reference: see /pages/how-to-convert/tablespoons-to-cups for tbsp ↔ cup + /pages/how-to-convert/ml-to-cups for direct mL conversion + /pages/how-to-convert/milliliters-to-tablespoons for mL ↔ tbsp.

Time ranges by condition

Condition	Duration	Note
US fluid ounce to cup	< 5 seconds	fl oz ÷ 8 = cups
UK fluid ounce (rare)	10 seconds	UK fl oz × 28.41 mL, then ÷ 236.6 mL for US cup
Pint to cups	5 seconds	1 US pint = 16 fl oz = 2 US cups

What changes the time

US vs UK. 1 US pint = 16 fl oz (473 mL). 1 UK pint = 20 fl oz (568 mL). 17% difference.
Weight oz vs fluid oz. Weight: 28.35 g. Fluid (US): 29.57 mL. Roughly equal for water; very different for oils/honey/syrup.
Legal vs customary cup. US customary = 236.6 mL (8 × 29.57). US legal (FDA labels) = 240 mL (8 × 30). 1.4% difference.

Common questions

Why is the US gallon different from the UK gallon?

US gallon = 128 US fl oz = 3.785 L. UK (imperial) gallon = 160 UK fl oz = 4.546 L. The UK gallon is 20% LARGER than the US gallon. The US gallon was set to the older "Queen Anne wine gallon" (231 cubic inches); the UK redefined its gallon in 1824 to 10 lb of water at specific conditions. If you use British recipes, "1 gallon" of liquid is much more than a US gallon.

How do I know if a recipe means weight oz or fluid oz?

Three checks: (1) Ingredient type — water, milk, oil, juice = almost always fluid oz (volume). Meat, cheese, butter, chocolate = almost always weight oz. (2) Whether the recipe also lists grams or mL — if it lists both, "oz" matches the unit type given. (3) Recipe origin — US/UK home cooking mixes both freely; pastry-quality recipes (King Arthur, ATK) typically specify "fl oz" for liquids and just "oz" for weight.

Are cup measurements consistent across countries?

No. US cup = 236.6 mL (customary) or 240 mL (legal). Metric cup (Australia, NZ, parts of UK/EU) = 250 mL. Imperial cup (rare; historical UK) = 284 mL. Japanese cup = 200 mL. When converting recipes from a different country, always identify which cup standard the recipe uses; the 5-20% variance affects most recipes meaningfully.

Sources

We cite primary research, expert practice, and authoritative reference. Higher-tier sources weighted heavier. See methodology.

Tier 1 · peer-reviewed / governmentalTier 2 · editorial referenceTier 3 · named practitioner

T1NIST — Customary System units — Authoritative US measurement definitions
T1FDA — Food Labeling Reference Amounts — US legal cup definition for nutrition labels
T2King Arthur Baking — measurement basics — Practical conversion guide
T1BIPM (UK + International) — Imperial pint — Historical UK fluid ounce + pint definitions

Verify this answerEvery number, range, and recommendation on this page traces to a cited source listed above. Click any source to read the original. See how we verify for the full source-tier discipline, or browse the citation graph to see every source we cite across 188 answers.

What could change this answer

honest uncertainty

We don’t know your specific equipment, ingredient batch, or environment. This answer is the best directional estimate from cited sources. Here’s where it’s less certain:

3 factors shift the answer. Your specific us vs uk, weight oz vs fluid oz, legal vs customary cup can move this estimate in either direction. The table below shows the documented ranges.
Range spans 3 documented conditions. Pick the row that matches your scenario; halfway between two rows is your best estimate. The widest condition you can imagine is the safer upper bound.
Treat as a directional starting point. Real-world equipment, ingredient batch, and ambient conditions cause natural variance the table cannot capture. Use sensory checks (sight, smell, touch, internal temperature when relevant) alongside this answer — not instead of it.
Backed by 4 cited sources — verify if precision matters. See the Sources section for primary references. Cross-check the cited materials when stakes are high: commercial production, food safety, allergens, dietary or medical considerations.
Verified today. If you found a better-sourced answer or our answer no longer matches reality, tell us — corrections are public and dated. The page exists to be accurate, not to be unchanged.

Cite this page

de Vries, P. (2026). How many fluid ounces in a cup?. AskedWell. Retrieved 2026-05-21, from https://askedwell.com/pages/how-to-convert/fluid-ounces-to-cups

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Last verified: 2026-05-21 · Published 2026-05-21

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