How many fluid ounces are in a cup?

In the US customary system, 1 cup equals exactly 8 US fluid ounces. A metric cup (used in Australia, Canada, and many international recipes) equals 250 mL, which is approximately 8.4535 US fluid ounces.

Why do US and metric cups give different results?

The US cup is defined as exactly 236.588 mL (8 US fl oz), while the metric cup is exactly 250 mL. Because the cup sizes differ, the number of cups per fluid ounce varies by system.

What is a US fluid ounce?

One US fluid ounce equals approximately 29.5735 mL. It is different from the UK (imperial) fluid ounce, which equals approximately 28.4131 mL. This converter uses the US fluid ounce.

How do I convert fluid ounces to cups without a calculator?

Divide the number of fluid ounces by 8 to get US cups. For example, 24 fl oz ÷ 8 = 3 cups. For metric cups, divide by 8.4535 — or simply use this converter.

Can I convert cups back to fluid ounces?

Yes. Click the swap button to reverse the conversion. Enter the number of cups and get the equivalent in US fluid ounces for both US and metric cup sizes.

Fluid Ounces to Cups Converter

Name: Fluid Ounces to Cups Converter
Availability: InStock
Author: Nham Vu

Enter a value in fluid ounces and instantly see the equivalent in US cups and metric cups.

Enter Volume in Fluid Ounces

Fluid Ounces (US fl oz)

Quick presets

Results

Enter fluid ounces above to see the conversion.

US Cups 1 cup = 8 fl oz

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Metric Cups (250 mL) 1 metric cup ≈ 8.4535 fl oz

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Quick reference

fl oz	US cups	Metric cups

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Summary

Enter a value in fluid ounces and instantly see the equivalent in US cups and metric cups.

How it works

Enter the number of fluid ounces in the input field.
The converter calculates US cups (1 cup = 8 US fl oz) in real time.
It also calculates metric cups (1 metric cup = 8.4535 US fl oz) simultaneously.
Use the swap button to convert cups back to fluid ounces.
Common preset values let you convert quickly without typing.

Use cases

Scale a recipe that lists liquids in fluid ounces to cup measurements.
Understand beverage serving sizes listed in fluid ounces vs. cups.
Convert a US recipe to metric measurements when cooking internationally.
Double-check liquid volumes when a measuring cup is your only tool.
Verify nutrition label serving sizes expressed in fluid ounces.
Convert bulk ingredient quantities for food production or catering.

Frequently Asked Questions

Last updated: 2026-07-01 · Reviewed by Nham Vu