Gallons (US) to Fluid Ounces Converter
Quick answer: To convert gallons to Fluid Ounces, multiply by 128. For example, 10 gal is 1,280 fl oz. One us gallon equals 128 fl oz.
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Use the Gallons (US) to Fluid Ounces Converter
Gallons (US) to Fluid Ounces formula and what each symbol means
fl oz = gal × 128
| Symbol | Meaning |
|---|---|
| gal | US gallon |
| fl oz | US fluid ounce |
Gallons (US) to Fluid Ounces examples
1 gal
1 gal × 128 = 128 fl oz.
10 gal
10 gal × 128 = 1,280 fl oz.
100 gal
100 gal × 128 = 12,800 fl oz.
Gallons (US) compared with Fluid Ounces
One gal is 128 times as large as one fl oz, so your number gets bigger when you convert gallons to Fluid Ounces and smaller when you convert back. If the answer is not larger than what you typed, you divided instead of multiplying.
About gallons and Fluid Ounces
US gallon (gal): The US liquid gallon, exactly 231 cubic inches or 3.785411784 litres. US fluid ounce (fl oz): The US fluid ounce, exactly 29.5735295625 millilitres.
Where gallons to Fluid Ounces conversions are used
Fuel, milk and bottled drinks are sold in litres or gallons depending on the country. Tanks, pools and shipping containers are specified in cubic metres or cubic feet.
How to calculate Gallons (US) to Fluid Ounces step by step
- Enter the value in gal (the starting unit).
- Multiply by 128, because 1 gal = 128 fl oz.
- The product is the value in fl oz. To go back, divide by 128 or multiply by 0.0078125.
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How to read your Gallons (US) to Fluid Ounces result
Quick estimate: multiply by about 130 to get Fluid Ounces from gallons; this is within 1.6% of the exact factor. The US gallon is exactly 3.785411784 litres and the imperial gallon is exactly 4.54609 litres, about 20% bigger.
| GALLONS (US) | FLUID OUNCES |
|---|---|
| 1 | 128 |
| 2 | 256 |
| 5 | 640 |
| 10 | 1,280 |
| 20 | 2,560 |
| 50 | 6,400 |
| 100 | 12,800 |
| 1,000 | 128,000 |
Fluid Ounces to Gallons (US): quick table
| FLUID OUNCES | GALLONS (US) |
|---|---|
| 1 | 0.0078125 |
| 5 | 0.0390625 |
| 10 | 0.078125 |
| 25 | 0.1953125 |
| 50 | 0.390625 |
| 100 | 0.78125 |
| 250 | 1.953125 |
| 500 | 3.90625 |
Common mistakes when calculating Gallons (US) to Fluid Ounces
- Confusing the US fluid ounce (about 29.57 mL) with the imperial fluid ounce (about 28.41 mL).
- Dividing when you should multiply: from gal to fl oz multiply by 128; from fl oz to gal divide by 128.
Gallons (US) to Fluid Ounces FAQ
How many fl oz are in 1 gal?
1 gal equals 128 fl oz.
How many gal are in 1 fl oz?
1 fl oz equals 0.0078125 gal.
Is 1 gal = 128 fl oz an exact conversion?
Yes. The us gallon and the us fluid ounce are both defined exactly in SI terms, so the ratio has no measurement uncertainty; 128 is just that ratio shown to 7 significant figures.
What is an uS fluid ounce (fl oz)?
The US fluid ounce, exactly 29.5735295625 millilitres.
How can I estimate gallons to Fluid Ounces in my head?
Quick estimate: multiply by about 130 to get Fluid Ounces from gallons; this is within 1.6% of the exact factor.
What is 25 gal in Fluid Ounces?
25 gal = 3,200 fl oz (since 25 × 128).
What is 80 gal in Fluid Ounces?
80 gal = 10,240 fl oz (since 80 × 128).
What is 500 gal in Fluid Ounces?
500 gal = 64,000 fl oz (since 500 × 128).
How many decimals should I keep when converting gal to fl oz?
Match the precision of your original measurement. For example, 1,280 fl oz rounds to 1,280 fl oz at 3 significant figures; keep more digits only for engineering or scientific work.
More in Volume converters
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Method, review and disclaimer
Edited by: Hemant Kumar and Anjita Rai, founders of ToolsVault (SEO and content professional, not a licensed adviser). Method: this tool runs in your browser using the formula shown on this page; the numbers you enter are not sent to our servers. Sources: NIST SP 811, Appendix B.8: conversion factors, NIST Handbook 44, Appendix C: units and systems of measurement