Quick answer
Volume units convert through litres. 1 US gallon equals 3.785412 litres, 4 quarts or 128 US fluid ounces.
Enter a value and choose the units. The calculator returns the converted volume.
Related tools: Barrel Volume Calculator: Approximate capacity of a barrel from head diameter, bung diameter and length.
How to use the Volume Converter
- Enter value.
- Choose from: Millilitre (mL), Litre (L), Cubic metre (m³), Cubic centimetre (cm³), US teaspoon and US tablespoon and 12 more.
- Choose to: Millilitre (mL), Litre (L), Cubic metre (m³), Cubic centimetre (cm³), US teaspoon and US tablespoon and 12 more.
- Enter decimal places (between 0 and 10). It starts at 4.
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Value | A number | — |
| From | Choose one: Millilitre (mL); Litre (L); Cubic metre (m³); Cubic centimetre (cm³); US teaspoon; US tablespoon; US fluid ounce; US cup; … | Starts at Millilitre (mL) |
| To | Choose one: Millilitre (mL); Litre (L); Cubic metre (m³); Cubic centimetre (cm³); US teaspoon; US tablespoon; US fluid ounce; US cup; … | Starts at Litre (L) |
| Decimal places | A number | ≥ 0, ≤ 10, starts at 4 |
Formula and method
Formula
result = value × (factor of source ÷ factor of target), base unit: litre
IEEE-754 double precision; displayed to the chosen number of decimal places (default 4). Very small or large results are shown in scientific notation.
Every unit is defined by an exact or published factor to the base unit (litre). The value is multiplied by the source factor and divided by the target factor.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Value = 1; From = US gallon; To = Litre (L); Decimal places = 6.
| Result | Value |
|---|---|
| US gallon → Litre (L) | 3.785412 |
| Input | 1 US gallon |
Example 2
Inputs: Value = 1; From = US cup; To = US tablespoon; Decimal places = 4.
| Result | Value |
|---|---|
| US cup → US tablespoon | 16 |
| Input | 1 US cup |
Example 3
Inputs: Value = 1; From = Imperial gallon; To = Litre (L); Decimal places = 5.
| Result | Value |
|---|---|
| Imperial gallon → Litre (L) | 4.54609 |
| Input | 1 Imperial gallon |
The first line is the headline result (uS gallon → Litre (L)). Below it the volume Converter lists input, which describe the same case from other angles. IEEE-754 double precision; displayed to the chosen number of decimal places (default 4). Very small or large results are shown in scientific notation.
Unit reference
Each unit expressed in the base unit used for the calculation. Conversions go through this base unit, so any unit can be converted to any other in the table.
| Unit | Equals (in litre) |
|---|---|
| Millilitre (mL) | 0.001 |
| Litre (L) | 1 |
| Cubic metre (m³) | 1000 |
| Cubic centimetre (cm³) | 0.001 |
| US teaspoon | 0.004928921594 |
| US tablespoon | 0.01478676478 |
| US fluid ounce | 0.02957352956 |
| US cup | 0.2365882365 |
| US pint | 0.473176473 |
| US quart | 0.946352946 |
| US gallon | 3.785411784 |
| Imperial gallon | 4.54609 |
| Imperial pint | 0.56826125 |
| Imperial fluid ounce | 0.0284130625 |
| Cubic foot (ft³) | 28.31684659 |
| Cubic inch (in³) | 0.016387064 |
| Cubic yard (yd³) | 764.554858 |
| Oil barrel (42 US gal) | 158.9872949 |
US customary units
1 gallon = 4 quarts = 8 pints = 16 cups = 128 fl oz. 1 cup = 236.588 mL and 1 tablespoon = 14.787 mL. The US and UK differ: an imperial gallon is 4.546 L.
Searches such as 'ml to grams' ask for a volume-to-weight conversion, which needs the density of the substance. This page converts between volume units only; for ingredients use the Cooking Ingredient Converter.
Metric
1 L = 1,000 mL = 1,000 cm³ = 0.001 m³. 1 m³ = 1,000 L = 264.17 US gallons. Volumes and weights relate only for a given substance, so use a weight converter for that.
How the result changes with value
Holding every other input at the first worked example, this table changes only value. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Value | US gallon → Litre (L) | Input |
|---|---|---|
| 0.5 | 1.892706 | 0.5 US gallon |
| 1 | 3.785412 | 1 US gallon |
| 2 | 7.570824 | 2 US gallon |
| 4 | 15.141647 | 4 US gallon |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Value: left empty shows "Enter value." beside that field and no result.
Choosing between the Volume Converter and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Aquarium Volume Calculator](/construction/aquarium-volume/) | length, width and water height | Capacity |
| [Pool Volume Calculator](/construction/pool-volume-calculator/) | shape, length and average depth | Pool volume |
| [Barrel Volume Calculator](/math/barrel-volume-capacity-calculator/) | head diameter, bung diameter and inside length | Capacity |
| [Beer Volume Converter](/converters/beer-volume/) | value, from and to | Half-barrel keg → Can or bottle, 12 US fl oz |
| [Square Feet to Cubic Yards Calculator](/converters/ft2-yd3/) | area and depth | Volume |
Background: unit conversion
Many customary units are defined exactly in terms of metric ones: since the 1959 International Yard and Pound Agreement an inch is exactly 2.54 cm and a pound is exactly 0.45359237 kg (NIST SP 811 lists these). So most length and mass conversions are exact apart from the rounding of the displayed result.
To convert, multiply the value by the source unit's factor to reach the base unit, then divide by the target unit's factor; the unit table on this page lists every factor used. Temperature and fuel economy are the exceptions, because they are not simple multiples.
Assumptions and limitations
- Negative values are allowed
- Zero converts to zero (except L/100 km, where zero is invalid)
- Units from different quantities cannot be converted
- Very large or tiny results switch to exponent notation
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for value to confirm this.
Frequently asked questions
How many mL in a cup?
A US cup is about 236.6 mL.
How many litres in a gallon?
A US gallon is 3.785 litres.
Is a UK pint the same as a US pint?
No, UK 568 mL versus US 473 mL.
What does the Volume Converter calculate?
Convert litres, gallons, cups, spoons and more. It returns US gallon → Litre (L) and Input.
What formula does the Volume Converter use?
result = value × (factor of source ÷ factor of target), base unit: litre. Every unit is defined by an exact or published factor to the base unit (litre).
What is an example of a volume result?
With value 1, from US gallon, to Litre (L) and decimal places 6, the uS gallon → Litre (L) is 3.785412.
Where does the method come from?
The method follows: NIST SP 811 (2008), Appendix B.8: US gallon = 231 in³ = 3.785411784 L exactly; UK Weights and Measures Act 1985: imperial gallon = 4.54609 L.
Related calculators
- Barrel Volume Calculator — Approximate capacity of a barrel from head diameter, bung diameter and length.
- Beer Volume Converter — Convert kegs, cans, bottles, pints and litres of beer.
- Square Feet to Cubic Yards Calculator — Cubic yards of material covering an area at a depth.
- Volume of a Hemisphere Calculator — Volume and surface area of a hemisphere.
Sources
- NIST SP 811 (2008), Appendix B.8: US gallon = 231 in³ = 3.785411784 L exactly
- UK Weights and Measures Act 1985: imperial gallon = 4.54609 L
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.