This converter turns imperial gallons into US cups instantly, using the exact factor 1 imperial gallon = 19.21519881 US cups. Type any number and the result updates as you go — nothing is sent to a server, so the arithmetic happens entirely in your browser.
Exactly 4.54609 litres, about 20% larger than the US gallon. The US legal cup used in recipes: 240 mL, or 236.6 mL by the customary definition.
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
imperial gallons- The amount you are converting, measured in imperial gallons
19.21519881- The exact number of US cups in one imperial gallon
US cups- The converted result
How it works, step by step
- Enter the number of imperial gallons you want to convert.
- The value is multiplied by 19.21519881, the exact conversion factor.
- The result is displayed in US cups, rounded for readability.
- The unrounded value and the reverse conversion appear underneath so you can verify it.
Worked examples
Converting 5 imperial gallons
Multiply 5 by 19.215199. That gives 96.076 US cups. A quick sanity check: one imperial gallon is larger than one US cup, so the number should get bigger — and it does.
Converting 72 imperial gallons
72 × 19.215199 = 1,383.49 US cups. Working backwards, 1,383.49 ÷ 19.215199 returns 72 imperial gallons, which confirms the factor is applied the right way round.
How to read your score
Frequently asked questions
How many US cups are in one imperial gallon?
Exactly 19.21519881. 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 imperial gallons to US cups?
Us Cups = imperial gallons × 19.21519881. To reverse it, divide instead: imperial gallons = US cups ÷ 19.21519881, which is the same as multiplying by 0.05204213654.
Is the imperial gallon bigger than the US cup?
Yes. One imperial gallon equals 19.2152 US cups, so it is the larger unit.
Why does my answer differ slightly from other imperial-gallons to cups 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 imperial gallon?
Exactly 4.54609 litres, about 20% larger than the US gallon.
What is a US cup?
The US legal cup used in recipes: 240 mL, or 236.6 mL by the customary definition.
Imperial Gallons to US cups reference table
| Imperial Gallons | Us Cups |
|---|---|
| 0.5 gal | 9.6076 cup |
| 1 gal | 19.2152 cup |
| 2 gal | 38.4304 cup |
| 3 gal | 57.6456 cup |
| 5 gal | 96.076 cup |
| 10 gal | 192.152 cup |
| 15 gal | 288.228 cup |
| 20 gal | 384.304 cup |
| 25 gal | 480.38 cup |
| 50 gal | 960.7599 cup |
| 75 gal | 1,441.14 cup |
| 100 gal | 1,921.52 cup |
| 250 gal | 4,803.8 cup |
| 500 gal | 9,607.6 cup |
| 1000 gal | 19,215.2 cup |
Exact factor: 1 imperial gallon = 19.21519881 US cups. Values rounded for display.