Volume Converter

Convert volume between liters, gallons, cups, fluid ounces, cubic meters, and more.

Value

From

Results update as you type.

Converted Volume

—

How it works

Volume measures the three-dimensional space a substance occupies, and it appears constantly in cooking, chemistry, construction, fuel, and shipping. The difficulty is that volume units differ sharply between the US and the rest of the world, and even within the US the definitions of cup, pint, gallon, and fluid ounce diverge from the imperial (UK) versions. A volume converter resolves this by translating any figure into a shared reference before producing the answer you need. The essentials worth remembering: a US gallon is 3.785 liters, while a UK imperial gallon is 4.546 liters — a 20 percent gap that matters when comparing fuel economy internationally. A US cup is about 240 mL, whereas a metric cup used in Australia and Canada is 250 mL, and US and UK fluid ounces also differ slightly. Because each unit holds a fixed ratio to the liter, this volume converter normalises every input to liters first, then scales to the target, so even awkward pairings like cubic feet to imperial gallons stay accurate. Home cooks, engineers, lab technicians, and drivers filling up abroad all lean on a volume converter to avoid the costly errors that come from mixing incompatible unit systems.

Formula

Convert to liters (base unit) then to target unit

Volume conversion is exact because each unit is a fixed multiple of the liter, which ties directly to the SI cubic meter (1 m³ = 1000 L). The converter scales the input up to liters using its ratio, then down to the requested unit, so no precision is lost across the range. Key ratios: 1 US gallon = 3.78541 L, 1 cup = 0.236588 L, 1 fl oz = 0.0295735 L, and 1 cubic meter = 1000 L.

Source:International System of Units (SI) — NIST

We review all our tools from time to time to ensure accuracy.

Worked example

Value:1From:gallonTo:liter

1 US gallon = 3.78541 liters. This is why fuel economy in the US (miles per gallon) differs numerically from countries that use liters per 100 km.

How to use this calculator

1
Enter your values
Enter value, from and to.
2
Adjust the options
Fine-tune any options to match your situation.
3
Read your result
Converted Volume updates instantly as you type — no button to press.

Frequently asked questions

How many cups are in a gallon?

In the US system: 1 gallon = 4 quarts = 8 pints = 16 cups = 128 fluid ounces. So there are exactly 16 US cups in 1 US gallon. A handy mnemonic: Gallon, Quarts, Pints, Cups — each step doubles the count: G=1, Q=4, P=8, C=16. This relationship is exact by definition in the US customary system.

What is the difference between a US gallon and a UK (imperial) gallon?

A US gallon is 3.78541 liters, while a UK imperial gallon is 4.54609 liters — about 20% larger. This is why UK cars appear to get better fuel economy in 'miles per gallon' than US cars — the UK gallon is larger, so more miles per gallon is easier. When comparing international fuel efficiency, always clarify which gallon is used. US fluid ounces and UK fluid ounces also differ: 1 US fl oz = 29.5735 mL; 1 UK fl oz = 28.4131 mL.

How many milliliters are in a cup?

A US legal cup (used in nutrition labeling) = 240 mL exactly. A US customary cup = 236.588 mL (based on the US gallon definition). An Australian/Canadian metric cup = 250 mL. For most cooking purposes, 240 mL per cup is the practical standard. If you're following a recipe from another country, knowing which cup definition they use can matter for precision baking, though for most home cooking the 10 mL difference between US and metric cups is negligible.

How do I convert liters to gallons?

To convert liters to US gallons, divide by 3.78541 (or multiply by 0.264172). For quick mental math: 4 liters ≈ 1 gallon (actual: 4 L = 1.057 gallons, so this is about 5.7% off). More precisely: 10 liters ≈ 2.64 gallons, 20 liters ≈ 5.28 gallons. When filling up a car with fuel abroad, this conversion helps estimate costs: a 50-liter tank holds about 13.2 US gallons.

What is the volume of a cubic foot in liters?

One cubic foot = 28.3168 liters (about 28.3 liters). One cubic meter = 1,000 liters = 264.172 US gallons. These conversions are important in construction (concrete volume, water storage tank sizing), HVAC (airflow in cubic feet per minute), and plumbing (pipe capacity in gallons or liters). A typical bathtub holds about 1.5–2.5 cubic feet (42–71 liters) of water when full.