🧪 cup to fl oz — US Cup to Fluid Ounce Converter

Convert volume units — liters, gallons, cups, milliliters, cubic meters, pints, quarts.

1 unit =
From
To
Formula 1 cup = 8 fl oz
UnitNameValue
L Liter 0.236588
mL Milliliter 236.588
Cubic Meter 0.000236588
gal(US) US Gallon 0.062499967
gal(UK) UK Gallon 0.052042085
qt US Quart 0.24999974
pt US Pint 0.5
fl oz Fluid Ounce 8
Last updated: March 2026

US Cup to Fluid Ounce Conversion Table

Common us cup values converted to fluid ounce — factor: 1 cup = 8 fl oz

US Cup (cup)Fluid Ounce (fl oz)Context
0.0625 cup0.5 fl ozTablespoon
0.125 cup1 fl ozEighth cup
0.25 cup2 fl ozQuarter cup
0.333 cup2.664 fl ozThird cup
0.5 cup4 fl ozHalf cup
1 cup8 fl ozOne cup
2 cup16 fl ozOne pint
4 cup32 fl ozOne quart
8 cup64 fl ozHalf gallon
16 cup128 fl ozOne gallon
32 cup256 fl oz2 gallons
64 cup512 fl oz4 gallons
128 cup1,024 fl oz8 gallons
256 cup2,048 fl ozLarge drum
512 cup4,096 fl ozLarge drum

About US Cup to Fluid Ounce Conversion

Converting us cup to fluid ounce comes up frequently in cooking, chemistry, medicine, and engineering. A recipe written in metric units may need to be adapted for a kitchen using fluid ounce, or a laboratory protocol may specify volumes in us cup that need to be measured with equipment calibrated in fluid ounce.

In everyday use, knowing that 5 cup = 40 fl oz and 10 cup = 80 fl oz covers most common situations. For bulk calculations, 100 cup = 800 fl oz is a useful anchor. The reverse conversion — fluid ounce back to us cup — uses the factor 0.125, so 1 fl oz = 0.125 cup.

All conversions use the internationally recognized factor of exactly 1 cup = 8 fl oz. Calculations are performed in IEEE 754 double-precision floating point, giving accuracy to at least 8 significant figures — more than sufficient for any practical application.

Quick Answer

Formula: Fluid Ounce = US Cup × 8

Multiply any us cup value by 8 to get fluid ounce. One us cup equals 8 fl oz.

Reverse: US Cup = Fluid Ounce × 0.125

Worked Examples

One US cup
1 cup × 8 = 8 fl oz
1 US cup = 8 fl oz — exact.
One fluid ounce
0.125 cup × 8 = 1 fl oz
0.125 cups = 1 fl oz.
One US quart
4 cup × 8 = 32 fl oz
4 cups = 32 fl oz = 1 quart.
One US gallon
16 cup × 8 = 128 fl oz
16 cups = 128 fl oz = 1 gallon.

Mental Math Tricks

× 8 exactly

Cups × 8 = fluid ounces. One cup = exactly eight fl oz.

Easy scaling

½ cup = 4 fl oz, ¼ cup = 2 fl oz.

Reverse

fl oz ÷ 8 = cups.

Who Uses This Conversion?

Home Baker

Follows American recipes using cups for flour, sugar, milk, and butter.

Recipe Developer

Tests and standardizes recipes in cup measurements before international publication.

Registered Dietitian

Uses cup portions as standardized serving-size references for dietary counseling.

Culinary Teacher

Teaches beginner cooks using cups as intuitive, equipment-free measuring tools.

Food Manufacturer

Converts cup-based recipes to liter or kilogram quantities for industrial production.

Expat Cook

Converts US cup measurements to metric mL when cooking American recipes abroad.

Frequently Asked Questions

About US Cup and Fluid Ounce

US Cup (cup)

The US customary cup is defined as exactly 8 US fluid ounces, or 236.588 mL. It was standardized by Fannie Farmer in her 1896 cookbook The Boston Cooking-School Cook Book.

The cup is the backbone of US baking: nearly every American recipe uses cup measurements for flour, sugar, butter, and liquids. Standard sets include 1 cup, ½ cup, ⅓ cup, and ¼ cup.

Interesting fact: Australia uses a metric cup of 250 mL, slightly larger than the US cup, which can cause recipe confusion in international cooking.

Fluid Ounce (fl oz)

The US fluid ounce is defined as 1/128 of a US gallon, exactly 29.5735 mL. The US and UK fl oz differ: the US is 29.57 mL while the Imperial fl oz is 28.41 mL.

Fluid ounces appear on every US beverage container: a soda can is 12 fl oz, a water bottle is 16.9 fl oz, and a US shot glass is 1.5 fl oz.

Interesting fact: Despite sharing the name 'ounce', the fluid ounce measures volume, not weight. One fl oz of water weighs about 1.04 oz, but one fl oz of honey weighs about 1.5 oz.