Convert volumes, keeping US and UK gallons apart

Each unit has a factor to the cubic meter. The milliliter is 10⁻⁶ m³, the liter 10⁻³ m³. Cubic inch and cubic foot are cubes of the international lengths. The US liquid gallon is 3.785411784 L (231 in³). The UK (imperial) gallon is 4.54609 L. A “gal” without qualifier on a US notice is almost always the US gallon; an old British recipe may still mean the imperial gallon.

V(m³) = x × kfrom ; y = V(m³) / kto

1 L = 0,001 m³ = 1 000 ml

1 gal US = 3,785411784 L ; 1 gal UK = 4,54609 L

The cubic meter is the SI unit of volume. The liter is accepted for use with SI. Gallon factors are NIST’s (US liquid gallon) and the imperial gallon definition in liters. There is no “average” gallon. A US petroleum gallon (barrel, etc.) is not treated separately: it is the same US liquid gallon. Concrete is ordered in m³ (or yd³): convert first, then use the concrete tool for L × W × T.

Value

Numeric capacity. For 250 ml to m³, type 250 and ml → m³ (0.00025 m³).

From

ml, L, m³, in³, ft³, gal US, gal UK. No pint as a direct option (1 US gal = 8 US pints).

To

Same list. For concrete, aim at m³.

Assumptions

• US gallon = US liquid gallon (231 in³), not the US dry gallon.
• UK gallon = imperial gallon (4.54609 L).
• 1 L = 0.001 m³ exactly.

Limits

• No pint, barrel, tablespoon, or fluid ounce as a single option.
• The US dry gallon (agriculture) is not listed.
• An irregular tank must be measured first; this tool only changes unit.

A “5 gallon” US jerry can is 18.93 L; in UK gallons, 5 gal ≈ 22.73 L. The gap pays for an order error. For 2 m³ of concrete, stay in m³: 2,000 L is not 2,000 gallons. Then connect length, width, and thickness in the concrete calculator.

• Choosing gal US for a British notice in imperial gallons.

  Gal UK = 4.54609 L. Gal US = 3.785411784 L. The gap is about 20%.

• Confusing liter and m³ by a factor of 10 instead of 1,000.

  1 m³ = 1,000 L, not 100 L. 1 L = 0.001 m³.

• Converting an area (m²) here.

  Volume has a thickness. Area has its own converter.

• Area converterFactors are SI areas and the international acre. A hectare is 10,000 m² exactly. The acre used here is not the arpent, nor a local survey acre.
• Concrete calculatorThe math starts from a rectangular box: volume in m³, then a waste margin. Mass uses 2,400 kg/m³, a typical normal-weight concrete density, not every mix.
• Length converterEvery value goes through the meter, then to the target unit. The inch is 25.4 mm exactly since the 1959 agreement, as in the NIST SI conversion factors.
• Weight (mass) converterEveryday speech says “weight”; SI speaks of mass. Conversion goes through the kilogram. The pound (lb) is 0.45359237 kg exactly, a NIST factor, not a weighing on Earth.
• Speed converterEvery speed routes through the metre per second. 1 km/h is exactly 1/3.6 m/s, and a knot is one nautical mile (1,852 m) per hour, not a statute mile.
• Angle converterEvery angle routes through the radian, the SI unit. A half turn is π radians, 180 degrees or 200 gradians: three ways of describing the same opening.

Written by Rédaction HexaCalc (editorial team). Content last updated: August 25, 2026. No third-party medical or financial review is claimed.

• NIST Guide to the SI, Appendix B: Conversion Factors — National Institute of Standards and Technology
• The International System of Units (SI) — Bureau international des poids et mesures (BIPM)