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Unit Conversions
Volume Converter — Gallons, Liters, Cups, Quarts & Cubic Feet
Switch between US and imperial liquid measures, metric volume and cubic units with exact factors
Volume is one of the trickiest conversions in everyday American life because two different gallons exist and the kitchen, the gas pump and the hardware store all speak different dialects. A recipe from Europe lists 250 mL of milk, your car takes 14 US gallons, a UK cocktail book calls for an imperial pint, and a fish tank is rated in cubic feet. This converter moves any value between the thirteen units you actually meet: liters (L), milliliters (mL), cubic meters (m³) on the metric side; cubic feet (ft³) and cubic inches (in³) for tanks, freight and construction; the full US liquid family — gallon, quart, pint, cup, fluid ounce, tablespoon and teaspoon; and the imperial (UK) gallon.
The method is simple and exact: every unit is converted to one base — the liter — and then back out to the target unit. Formula: liters = value × (factor of the FROM unit), then result = liters ÷ (factor of the TO unit).
The US fluid units are defined from the US gallon = exactly 231 cubic inches = 3.785411784 L. From there: 1 gallon = 4 quarts = 8 pints = 16 cups = 128 fluid ounces, and 1 fluid ounce = 2 tablespoons = 6 teaspoons. The imperial gallon is bigger — 4.54609 L, about 20% larger than the US gallon, which is exactly why a "20 mpg" US car looks worse than a "20 mpg" UK car: they're not measuring the same gallon.
Worked example — convert 5 US gallons to liters. 5 × 3.785411784 = 18.927 L. Going the other way, a 2-liter soda bottle is 2 ÷ 3.785411784 = 0.528 US gallons, just over half a gallon.
The biggest mistake is assuming a US cup, ounce or pint equals its UK cousin — they don't. A US pint is 16 fl oz; an imperial pint is 20 imperial fl oz (≈ 19.2 US fl oz). For dialing in small cooking amounts like cups, tablespoons and teaspoons, our cooking measurement converter adds ingredient density notes for grams. This tool focuses on exact, unit-to-unit volume — pick a value, a from unit and a to unit and you'll get a full table showing the same volume in every common unit at once.
This converter is built for capacity and engineering volumes — tanks, containers, fuel, shipping and the US-vs-imperial gallon gap. For kitchen amounts like cups, tablespoons and teaspoons in a recipe, use the Cooking Measurement Converter instead, which also handles cup-to-grams for common ingredients.
📖 See also: Cups to mL: A Complete Kitchen Conversion Guide
Calculator
Fill in the fields and click "Calculate" for instant results.
📰 Formula
• Convert to liters: liters = value × (factor of the FROM unit) • Convert out: result = liters ÷ (factor of the TO unit) • L = 1 • mL = 0.001 • m³ = 1000 • ft³ = 28.316846592 • in³ = 0.016387064 • US gal = 3.785411784 • US qt = 0.946352946 • US pt = 0.473176473 • US cup = 0.2365882365 • US fl oz = 0.0295735295625 • US tbsp = 0.01478676478 • US tsp = 0.00492892159 • imperial (UK) gal = 4.54609
📰 Formula
• Convert to liters: liters = value × (factor of the FROM unit) • Convert out: result = liters ÷ (factor of the TO unit) • L = 1 • mL = 0.001 • m³ = 1000 • ft³ = 28.316846592 • in³ = 0.016387064 • US gal = 3.785411784 • US qt = 0.946352946 • US pt = 0.473176473 • US cup = 0.2365882365 • US fl oz = 0.0295735295625 • US tbsp = 0.01478676478 • US tsp = 0.00492892159 • imperial (UK) gal = 4.54609
🧪 Worked examples
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Example 2
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Example 3
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Example 4
⚠️ Common mistakes
- Treating a US gallon and an imperial (UK) gallon as the same — the imperial one is about 20% larger (4.54609 L vs 3.785411784 L).
- Assuming a US cup, pint or fluid ounce equals its UK counterpart — a US pint is 16 fl oz but an imperial pint is 20 imperial fl oz.
- Confusing milliliters and liters — there are 1,000 mL in 1 L, so the value is 1,000× different.
- Mixing up cubic feet with cubic inches — there are 1,728 cubic inches in a cubic foot, not 12.
- Using a rounded factor like 1 gallon ≈ 3.8 L instead of the exact 3.785411784 on large volumes.
💡 Tips
- Memorize the gallon ladder: 1 US gal = 4 qt = 8 pt = 16 cups = 128 fl oz, and 1 fl oz = 2 tbsp = 6 tsp.
- Convert through liters as a single base — it removes guesswork between any two volume units.
- For a quick gut check: 1 US gallon ≈ 3.79 L, 1 liter ≈ 0.264 US gal, and 1 cubic foot ≈ 7.48 US gallons.
- Always label which gallon you mean — say 'US gallons' or 'imperial gallons' on recipes, mpg and orders to avoid a 20% error.
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❓ Frequently asked questions
How many liters are in a US gallon?
Exactly 3.785411784 liters. The US gallon is defined as 231 cubic inches, which works out to 3.785411784 L, so 5 gallons = 18.927 L.
What is the difference between a US gallon and an imperial gallon?
The US gallon is 3.785411784 L and the imperial (UK) gallon is 4.54609 L — about 20% larger. So 1 imperial gallon equals 1.201 US gallons, which is why US and UK mpg figures aren't comparable.
How many fluid ounces are in a cup, pint and gallon?
In US measures: 1 cup = 8 fl oz, 1 pint = 16 fl oz, 1 quart = 32 fl oz, and 1 gallon = 128 fl oz. Note UK fluid ounces and pints differ, so don't mix the two systems.
How do I convert milliliters to cups?
Divide milliliters by 236.5882365 to get US cups. For example, 250 mL ÷ 236.5882365 = 1.057 US cups, just over a cup.
How many cubic feet are in a gallon?
1 US gallon is about 0.1337 cubic feet, and 1 cubic foot holds about 7.481 US gallons. This matters for sizing aquariums, water tanks and shipping volumes.
How many tablespoons are in a cup?
There are 16 US tablespoons in a US cup, and 3 teaspoons in a tablespoon — so a cup is 48 teaspoons. Half a cup is 8 tablespoons and a quarter cup is 4 tablespoons.
How do I convert liters to gallons in my head?
Multiply liters by about 0.264 for a quick estimate, or divide by 3.785411784 for an exact answer. A 2-liter bottle is roughly 0.53 US gallons.
Are these volume conversion factors exact or approximate?
They're exact. The US gallon (231 cubic inches), the cubic inch (from the 2.54 cm inch) and the imperial gallon (4.54609 L since 1985) are all defined by international agreement, so this converter gives official results, not approximations.
Should I use this or a cooking measurement converter?
Use this volume converter for exact unit-to-unit results across gallons, liters and cubic units. For kitchen-focused work with small units and gram weights by ingredient, use the cooking measurement converter, which factors in density.