Volume Unit Converter

Tank capacities, chemical dosing and sample volumes are quoted in litres on one datasheet, gallons on another and cubic metres on the third, while a barrel means something different to a chemist and a petroleum engineer. This converter settles them exactly, including the US and imperial gallon split.

Convert volume unit units

Value

From

Why volume units collide

Volume mixes three problems at once: the metric decimal stack (m³, L, mL), the imperial gallon split (US 3.785 L vs UK 4.546 L), and the cubic-foot / barrel conventions of tanks and petroleum. A wrong gallon is a 20% error, big enough to overflow a day tank or short a dose.

All factors are exact definitions, so the converter is exact. The only thing to watch is which gallon — this tool labels both and never substitutes one for the other.

Which unit where

Litres and cubic metres are the metric tank and flow standard; millilitres rule reagent and sample volumes. US gallons dominate North American tank and dosing specs, imperial gallons appear in older Commonwealth equipment, and barrels (42 US gal) are the petroleum volume.

Complete conversion reference

Convert 1 unit to	m³	L	mL	cm³	US gal	imp gal	ft³	bbl
1 m³	1	1000	1e+06	1e+06	264.172	219.969	35.3147	6.28981
1 L	0.001	1	1000	1000	0.264172	0.219969	0.0353147	0.00628981
1 mL	1e-06	0.001	1	1	0.000264172	0.000219969	3.53147e-05	6.28981e-06
1 cm³	1e-06	0.001	1	1	0.000264172	0.000219969	3.53147e-05	6.28981e-06
1 US gal	0.00378541	3.78541	3785.41	3785.41	1	0.832674	0.133681	0.0238095
1 imp gal	0.00454609	4.54609	4546.09	4546.09	1.20095	1	0.160544	0.028594
1 ft³	0.0283168	28.3168	28316.8	28316.8	7.48052	6.22884	1	0.178108
1 bbl	0.158987	158.987	158987	158987	42	34.9723	5.61458	1

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Frequently asked

How many litres in a US gallon?

Exactly 3.785411784 L. The imperial (UK) gallon is 4.54609 L — about 20% larger — so always confirm which gallon a spec means before converting a tank or dose volume.

What is 1 barrel in litres?

One petroleum barrel is 42 US gallons, or about 158.987 L (0.158987 m³). The barrel is a petroleum volume; do not confuse it with the small barrel used for reagents.

Is a cubic foot the same as a gallon?

No. One cubic foot is about 7.4805 US gallons or 28.3168 L. ft³ is common for tank and vessel geometry, while gallons are the practical fill and dose unit.

Why do datasheets mix m³ and litres?

m³ suits large tank and plant volumes; litres suit day tanks, drums and dosing. Convert at the boundary rather than carrying both through one calculation to avoid a factor-of-1000 slip.

This page performs exact unit arithmetic with no physical assumption beyond the stated reference (for example mH₂O assumes water near 4 °C, and pH follows its logarithmic definition). It is a working aid, not a substitute for the measurement method named in your permit.