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Units & conversions ¡ Updated 2026-10-04

Common Volume Conversions Explained

Cooking, fuel, and lab notes jump between millilitres, litres, cups, and gallons. Metric volume is decimal and consistent; US customary kitchen measures are defined, but they are not the same as imperial UK measures.

Metric volume

1 litre = 1,000 millilitres. A cubic metre is 1,000 litres. For water near room temperature, 1 ml is about 1 gram, which is why kitchen scales and measuring jugs often agree closely for watery liquids.

US liquid kitchen anchors

US customary liquid (common cooking)

UnitUS definition (approx. metric)
1 US cup240 ml (nutrition labeling often uses 240 ml)
1 US pint2 cups ≈ 473 ml
1 US quart2 pints ≈ 946 ml
1 US gallon4 quarts ≈ 3.785 l

Older recipes sometimes treat a cup as 236.588 ml (exactly 1/16 of a US gallon). For home cooking the difference is small; for lab work, use the definition your protocol states.

Imperial gallons are larger

1 imperial gallon ≈ 4.546 litres, noticeably more than a US gallon. Always check which gallon a fuel economy figure or older British recipe intends.

  • Prefer grams on a scale for baking when precision matters more than cup marks.
  • Do not mix US and imperial fluid ounces in the same calculation.
  • For medicine dosing, follow the labeled units; do not improvise kitchen conversions.

SmartKitio’s volume converter lists the unit system on the tool. Pair pages such as litres↔gallons follow the factors documented on that page.

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