What this converter does
This tool converts liquid volume between the metric system (liters and milliliters) and the US fluid (customary) system of gallons, pints and fluid ounces, in both directions. It uses US (United States) liquid units only — not the UK Imperial system. The Imperial gallon (4.54609 L) and Imperial pint/ounce are larger and different, so do not mix the two systems.
How to use it
Pick a Unit system. Choose Metric and enter a value in liters to convert into US fluid units. Choose US fluid and enter any combination of gallons, pints and fluid ounces — the three boxes are summed into one total volume before conversion. The results panel always shows the full set of equivalents: a mixed "gallons + pints + ounces" breakdown plus the totals expressed purely in gallons, pints, fluid ounces, liters and milliliters.
The formula explained
The liter is the SI base used internally. The exact US conversion factors are 1 US gallon = \(3.785411784\) L (= 231 cubic inches), 1 US pint = \(\frac{1}{8}\) gallon = \(0.473176473\) L, and 1 US fluid ounce = \(\frac{1}{128}\) gallon = \(\frac{1}{8}\) pint = \(0.0295735295625\) L. The full conversion is:
$$L = \text{Gallons} \times 3.785411784 + \text{Pints} \times 0.473176473 + \text{Fl oz} \times 0.0295735296$$and going the other way:
$$\begin{gathered} \text{Gallons} = \frac{L}{3.785411784}, \quad \text{Pints} = \frac{L}{0.473176473}, \quad \text{Fl oz} = \frac{L}{0.0295735296} \\[1.5em] \text{where}\quad L = \text{Volume (L)} \end{gathered}$$Note that 1 US pint = 16 US fluid ounces (Imperial uses 20). Milliliters are simply liters x 1000. The mixed breakdown takes whole gallons, then whole remaining pints (0–7), then the leftover ounces.
Worked example
For 1 liter: total gallons = \(1 / 3.785411784 = 0.264172\) gal; total pints = \(1 / 0.473176473 = 2.113376\) pt; total ounces = \(1 / 0.0295735295625 = 33.81402\) fl oz; that is 1000 mL. The mixed breakdown is 0 gal, 2 pt and 1.814 fl oz. Going the other way, 1 US gallon = \(3.785411784\) L = \(3785.411784\) mL = 8 pints = 128 fluid ounces.
FAQ
Are these US or UK units? US fluid units. The UK Imperial gallon, pint and ounce are different and not supported here.
How many fluid ounces are in a US pint? 16 US fluid ounces make 1 US pint, and 8 pints make 1 gallon.
What if I leave the pint and ounce boxes blank? Blank US fluid fields are treated as zero, so you can convert just gallons if you wish.
