ConvBolt — Unit ConverterFluid ounces to US gallons Converter
Converting fluid ounces to US gallons is a multiplication by a fixed factor: 1 fl oz = 0.0078125 gal. The table below covers the values people look up most often, and the formula section shows exactly where that factor comes from.
Because one fluid ounce works out to 0.0078125 gal, the us gallon is the far smaller unit of the two: a figure given in us gallon always carries a smaller number than the same measurement in fluid ounce. A chart drawn in fl oz can hide that, so check which label the axis uses before you compare two readings.
Kitchen and workshop measuring are where this pair comes up: a jug marked in fluid ounces alongside a recipe or container printed in US gallons is the classic case, and it is why the two labels rarely agree to the eye.
The conversion factor used here is 0.0078125 gal per fluid ounce (7 significant digits as shown). Kept to seven figures it covers professional measurement; if you round it to two or three decimals for a spreadsheet, the error scales with the input — at a value of 1,000 fl oz a factor rounded to three decimals can be off by a measurable amount. The reverse direction uses 128 fl oz per gal, the exact reciprocal, so a round trip through both pages returns your original number.
Fluid ounces to US gallons formula
Use this formula to convert any fluid ounce value to US gallons:
Worked example: 100 fl oz × 0.0078125 = 0.78125 gal.
Fluid ounces to US gallons conversion table
| Fluid ounces (fl oz) | US gallons (gal) |
|---|---|
| 0.5 fl oz | 0.00390625 gal |
| 1 fl oz | 0.0078125 gal |
| 2 fl oz | 0.015625 gal |
| 5 fl oz | 0.0390625 gal |
| 10 fl oz | 0.078125 gal |
| 20 fl oz | 0.15625 gal |
| 50 fl oz | 0.390625 gal |
| 100 fl oz | 0.78125 gal |
| 500 fl oz | 3.90625 gal |
| 1000 fl oz | 7.8125 gal |
How to convert fluid ounces to US gallons
Multiply the fluid ounce value by 0.0078125 to get the equivalent in US gallons. This single factor works for every value in the table above and for anything else you need — there is no per-value adjustment, which is why a conversion table and a calculator always agree.
If you need the opposite direction, use the US gallons to Fluid ounces converter instead of dividing by hand; both pages use the same source factors. For every other fl oz conversion in one place, see the fl oz conversion hub.
Frequently asked questions
How many US gallons are in 1 fluid ounce?
1 fluid ounce = 0.0078125 gal.
What is 100 fluid ounces in US gallons?
100 fl oz = 0.78125 gal.
Is converting fluid ounces to US gallons the same as US gallons to fluid ounces?
No — the direction changes the multiplier. The reverse conversion (1 gal = 128 fl oz) is on the US gallons to Fluid ounces page.
Related conversions
Try the ConvBolt Unit Converter for any other volume unit, browse the Volume conversions, or read our conversion guides.