This converter turns US cups into US fluid ounces instantly, using the exact factor 1 US cup = 8 US fluid ounces. Type any number and the result updates as you go — nothing is sent to a server, so the arithmetic happens entirely in your browser.
The US legal cup used in recipes: 240 mL, or 236.6 mL by the customary definition. One eighth of a US cup, roughly 29.57 millilitres.
Because the relationship is a simple proportion, one multiplication does the whole job. The table further down gives pre-computed values for the amounts people look up most often, and the result panel also reports the reverse conversion so you can check the figure both ways.
The formula
US cups- The amount you are converting, measured in US cups
8- The exact number of US fluid ounces in one US cup
US fluid ounces- The converted result
How it works, step by step
- Enter the number of US cups you want to convert.
- The value is multiplied by 8, the exact conversion factor.
- The result is displayed in US fluid ounces, rounded for readability.
- The unrounded value and the reverse conversion appear underneath so you can verify it.
Worked examples
Converting 5 US cups
Multiply 5 by 8. That gives 40 US fluid ounces. A quick sanity check: one US cup is larger than one US fluid ounce, so the number should get bigger — and it does.
Converting 72 US cups
72 × 8 = 576 US fluid ounces. Working backwards, 576 ÷ 8 returns 72 US cups, which confirms the factor is applied the right way round.
How to read your score
Frequently asked questions
How many US fluid ounces are in one US cup?
Exactly 8. Every conversion on this page is that single number multiplied by your input, so the result carries no rounding error beyond what is shown.
What is the formula to convert US cups to US fluid ounces?
Us Fluid Ounces = US cups × 8. To reverse it, divide instead: US cups = US fluid ounces ÷ 8, which is the same as multiplying by 0.125.
Is the US cup bigger than the US fluid ounce?
Yes. One US cup equals 8 US fluid ounces, so it is the larger unit.
Why does my answer differ slightly from other cups to us-fluid-ounces converters?
Most differences come from rounding the factor too early. This tool keeps full double precision through the calculation and only rounds at the final display step, and it also shows the unrounded value so you can see exactly where any difference appears.
What is a US cup?
The US legal cup used in recipes: 240 mL, or 236.6 mL by the customary definition.
What is a US fluid ounce?
One eighth of a US cup, roughly 29.57 millilitres.
Us Cups to US fluid ounces reference table
| Us Cups | Us Fluid Ounces |
|---|---|
| 0.5 cup | 4 fl oz |
| 1 cup | 8 fl oz |
| 2 cup | 16 fl oz |
| 3 cup | 24 fl oz |
| 5 cup | 40 fl oz |
| 10 cup | 80 fl oz |
| 15 cup | 120 fl oz |
| 20 cup | 160 fl oz |
| 25 cup | 200 fl oz |
| 50 cup | 400 fl oz |
| 75 cup | 600 fl oz |
| 100 cup | 800 fl oz |
| 250 cup | 2,000 fl oz |
| 500 cup | 4,000 fl oz |
| 1000 cup | 8,000 fl oz |
Exact factor: 1 US cup = 8 US fluid ounces. Values rounded for display.