Charles Law Calculator

Volume Converter

Type into any one of the eight fields below — litres, millilitres, cubic centimetres, cubic metres, cubic feet, cubic inches, US gallons, or UK gallons — and the rest update instantly, live, with no button to press.

All eight fields update together — edit any one and the rest convert instantly, so the field you're typing into is never overwritten while you type.

Why Volume Units Matter for Gas Calculations

Every gas law equation on this site — Charles' law, Boyle's law, the combined gas law, and the ideal gas law — works correctly in any consistent volume unit. Volume is one of the two variables Boyle's law relates to pressure, it's one of two variables Charles' law relates to temperature, and it shows up in every rearrangement of PV = nRT. None of that math cares whether you're counting litres, cubic feet, or gallons.

What the math does care about is consistency. If you enter an initial volume in litres and a final volume in cubic feet without converting one of them first, the calculator has no way to know the two numbers don't share a scale — it will still produce an answer, and that answer will be silently wrong by whatever factor separates the two units. This is one of the most common real-world mistakes in gas law problem sets: a homework question mixes metric and imperial units on purpose, expecting the student to convert first, and a rushed calculation skips that step entirely.

This converter exists to catch that before it happens. Get both of your volumes into the same unit here first, then solve it on the Charles law calculator with numbers that are already comparable. The same rule applies to the combined gas law calculator, which needs its own two volume fields in matching units, and to the ideal gas law calculator, which typically wants volume converted to cubic metres or litres internally before it's multiplied against pressure.

Metric units — litres, millilitres, and cubic metres — are the default across most scientific work worldwide, including chemistry and physics coursework almost anywhere outside the United States. Cubic feet, cubic inches, and gallons persist in US engineering, HVAC and plumbing specifications, fuel tank ratings, and everyday household contexts, which is exactly why a real gas-law problem is more likely than you'd expect to hand you one volume in each system.

Volume Conversion Reference Table

Three common starting volumes, each converted into every other unit the calculator supports. Every figure below is generated directly from the same conversion code that drives the live converter above, so it can't drift out of sync with what you see on screen.

Volume conversion reference table
Unit 1 L1 US gal1 m³
L Litres —3.78541181000
mL Millilitres 10003785.41181000000
cm³ Cubic centimetres 10003785.41181000000
m³ Cubic metres 0.0010.0037854118—
ft³ Cubic feet 0.0353146670.1336805635.314667
in³ Cubic inches 61.02374423161023.744
US gal US liquid gallons 0.26417205—264.17205
UK gal UK (imperial) gallons 0.219969250.83267418219.96925

Frequently Asked Questions About Volume Conversion

  • What is the difference between a US gallon and a UK gallon?

    They are different sizes entirely — a US liquid gallon is 3.785411784 litres, while a UK (imperial) gallon is 4.54609 litres, about 20% larger. Always check which one a source means before converting fuel economy, tank capacity, or lab reagent volumes.

  • How many millilitres are in a litre?

    Exactly 1,000 mL make up 1 L. The metric system defines every volume unit as a power-of-ten multiple of the litre, which is why converting between L, mL, and m³ never introduces rounding error the way imperial conversions can.

  • Why are cm³ and mL treated as the same unit?

    Because they are the same unit by definition: 1 cubic centimetre occupies exactly the same space as 1 millilitre, with no rounding involved. Medical and laboratory equipment often prints "cc" (cubic centimetre) where a chemistry textbook would print "mL" — the number never changes when you swap labels.

  • How do I convert cubic feet to litres?

    Multiply the cubic-foot value by 28.316846592 to get litres, since that is exactly how many litres fit in one cubic foot. The converter above does this automatically the moment you type a number into the ft³ field.

  • Why does 1 cubic inch convert to such a small number of litres?

    A cubic inch is a tiny volume — about 16.4 millilitres — because an inch itself is a short length, and cubing a short length gives an even smaller volume. It shows up mainly in US engine displacement and machining specifications, where litres would be an awkward unit to work in.

  • Is a cubic metre a practical unit for a gas law calculation?

    Yes, especially for the SI form of the ideal gas law. A cubic metre is 1,000 litres, so it tends to appear when volumes are large — industrial gas storage, HVAC systems, or any calculation where the litre would produce an unwieldy number of digits.

  • Can I trust this converter for a lab report or homework answer?

    The eight conversion factors used here are the standard exact or measured definitions (for example, 1 US gallon = 3.785411784 L exactly, by definition of the US gallon). Round the displayed result to the number of significant figures your assignment or instrument actually supports.

Related Gas Law Calculators

Once your volumes are in matching units, these companion tools cover the rest of the gas law family.