What is a Volume Unit Converter?
The volume unit converter switches between mL, L, m³, gallons, cups, and fluid ounces.
How it's calculated
1 L = 1,000 mL = 1,000 cm³, 1 m³ = 1,000 L, 1 US gallon = 3.785 L, 1 UK gallon = 4.546 L
Units that are easy to mix up
| Units | Why it's confusing | How to tell them apart |
|---|---|---|
| US gallon vs UK gallon | Same word, different size | US 3.785L, UK (Imperial) 4.546L — about 20% apart |
| cc vs mL | Look like different units | Exactly equal (1cc=1mL), commonly used for engine displacement |
There are two different gallons
Same word, but a 20% difference. The US gallon (3.785 L) is based on the old English wine gallon, while the UK gallon (4.546 L) was redefined in 1824 as the volume of 10 pounds of water. When the US inherited British units, it kept an older definition that Britain later changed — that split is why you must check which gallon a fuel-economy figure (mpg) uses before comparing numbers.
Good to know
- 1 L = 1,000 cm³ is by design — the liter was originally defined as the volume of a 10cm cube, and since 1L of water weighs exactly 1kg, length, volume, and weight are all elegantly linked in the metric system.
- cc and mL are identical. 1 cc = 1 cm³ = 1 mL, so a 125cc motorcycle engine displaces 125 mL.
- 1 m³ (1 CBM) equals 1,000 L — the same volume unit used in shipping and the liter you buy bottled water in are part of the same system.
- Fluid ounces differ too: the US fl oz is about 29.6 mL, the UK (Imperial) fl oz is about 28.4 mL.
- Crude oil is measured in barrels (159 L) — a holdover from 19th-century Pennsylvania oil fields, where oil was literally shipped in wooden barrels, a practice that became the international standard.
Frequently asked questions
Q. Is 1 cc the same as 1 mL?
Yes, exactly. cc (cubic centimeter) and mL are the same volume.
Q. Should I use a US or UK gallon?
Check the source. US sources use 3.785 L; UK/Australian sources use 4.546 L.
Q. How many liters is 1 m³?
1,000 L — the same volume as 1 CBM used in freight shipping.