Volume Converter

Volume spans kitchen recipes, fuel tanks, swimming pools and concrete pours — and two different “gallons” exist to confuse everyone. This volume converter uses US customary units (the smaller gallon) and converts between liters, milliliters, cubic meters, cubic feet, cups, pints, fluid ounces and gallons.

All factors trace back to exact definitions: 1 US gallon = 3.785411784 L exactly.

Enter valid values to see the results.

Formula

Result = Value × (from-unit in liters) ÷ (to-unit in liters)

US units are used: 1 US gal = 3.785 L, 1 cup = 236.6 mL, 1 fl oz = 29.57 mL. The UK (imperial) gallon is larger at 4.546 L — check which system a recipe or manual uses.

What you need

Enter the volume and pick the source and target units.
For cooking, cups and fluid ounces are US customary; metric recipes use mL and grams.
For large volumes (pools, concrete), m³ and ft³ are the practical units — 1 m³ = 1,000 L.

Worked example

A 10 L fuel can in US gallons: 10 ÷ 3.785411784 = 2.642 gal. A recipe calling for 2 cups of milk needs 2 × 236.6 = 473 mL — just under half a liter.

Practical tips

Kitchen anchor: 1 cup ≈ 240 mL (236.6 exactly), 1 tablespoon = 14.8 mL, 1 teaspoon = 4.9 mL.
1 m³ of water weighs almost exactly 1 tonne — a handy bridge between volume and weight.
Engine displacement in liters converts to cubic inches at 1 L = 61.02 in³: a 2.0 L engine is 122 in³.
For pool volumes, calculate the volume first with the Pool Volume Calculator, then convert here.

Volume conversion quick reference (US units)

Unit	In liters	Common use
1 fl oz	0.0296 L	Drinks, medicine
1 cup	0.2366 L	Cooking
1 gallon (US)	3.785 L	Fuel, paint
1 ft³	28.317 L	Appliances, rooms

Common mistakes

1 Mixing US and UK gallons: 1 UK gal = 4.546 L vs 1 US gal = 3.785 L — a 20% difference.
2 Confusing fluid ounces (volume) with ounces (weight) — they only coincide for water.
3 Using length conversion factors directly: 1 m³ is 35.3 ft³, not 3.28.

Frequently asked questions

How many liters are in a US gallon?

Exactly 3.785411784 L. A UK (imperial) gallon is 4.54609 L — about 20% larger.

How many milliliters are in a cup?

One US cup = 236.588 mL (often rounded to 240 mL in recipes). A metric cup used elsewhere is 250 mL.

How do I convert cubic meters to liters?

Multiply by 1,000: 1 m³ = 1,000 L exactly. A 2.5 m³ pool holds 2,500 liters.

Is a fluid ounce the same as an ounce?

No. A fluid ounce measures volume (29.57 mL); an ounce measures weight (28.35 g). They match only for water-like liquids.