This converter turns imperial gallons into imperial fluid ounces instantly, using the exact factor 1 imperial gallon = 160 imperial 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.
Exactly 4.54609 litres, about 20% larger than the US gallon. The UK fluid ounce, about 4% smaller than its US counterpart.
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
160- The exact number of imperial fluid ounces in one imperial gallon
imperial fluid ounces- The converted result
How it works, step by step
- Enter the number of imperial gallons you want to convert.
- The value is multiplied by 160, the exact conversion factor.
- The result is displayed in imperial fluid ounces, 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 160. That gives 800 imperial fluid ounces. A quick sanity check: one imperial gallon is larger than one imperial fluid ounce, so the number should get bigger — and it does.
Converting 72 imperial gallons
72 × 160 = 11,520 imperial fluid ounces. Working backwards, 11,520 ÷ 160 returns 72 imperial gallons, which confirms the factor is applied the right way round.
How to read your score
Frequently asked questions
How many imperial fluid ounces are in one imperial gallon?
Exactly 160. 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 imperial fluid ounces?
Imperial Fluid Ounces = imperial gallons × 160. To reverse it, divide instead: imperial gallons = imperial fluid ounces ÷ 160, which is the same as multiplying by 0.00625.
Is the imperial gallon bigger than the imperial fluid ounce?
Yes. One imperial gallon equals 160 imperial fluid ounces, so it is the larger unit.
Why does my answer differ slightly from other imperial-gallons to imperial-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 imperial gallon?
Exactly 4.54609 litres, about 20% larger than the US gallon.
What is a imperial fluid ounce?
The UK fluid ounce, about 4% smaller than its US counterpart.
Imperial Gallons to imperial fluid ounces reference table
| Imperial Gallons | Imperial Fluid Ounces |
|---|---|
| 0.5 gal | 80 fl oz |
| 1 gal | 160 fl oz |
| 2 gal | 320 fl oz |
| 3 gal | 480 fl oz |
| 5 gal | 800 fl oz |
| 10 gal | 1,600 fl oz |
| 15 gal | 2,400 fl oz |
| 20 gal | 3,200 fl oz |
| 25 gal | 4,000 fl oz |
| 50 gal | 8,000 fl oz |
| 75 gal | 12,000 fl oz |
| 100 gal | 16,000 fl oz |
| 250 gal | 40,000 fl oz |
| 500 gal | 80,000 fl oz |
| 1000 gal | 160,000 fl oz |
Exact factor: 1 imperial gallon = 160 imperial fluid ounces. Values rounded for display.