Unit conversion guide
Volume Conversion Guide
Volume conversion explained for millilitres, litres, cups, tablespoons, fluid ounces and gallons.
Updated 22 July 2026 • Reviewed by Tools by Layna Editorial Team • General information only
Volume Conversion Guide was checked for calculator fit, assumptions, examples, risk notes, related links and the point where an official source or qualified professional is more appropriate.
Volume conversion is useful for recipes, liquids, containers and labels. It is also one of the easiest places to make a quiet mistake because cup and tablespoon sizes vary by country.
Metric volume
The metric relationship is clean: 1000 ml equals 1 litre. One cubic metre equals 1000 litres. These conversions are reliable and easy to scale.
Cooking measures
Australian recipes commonly use 250 ml cups, 20 ml tablespoons and 5 ml teaspoons. US measures are different, so recipe source matters.
Fluid ounces and gallons
US fluid ounces and gallons are not the same as imperial fluid ounces and gallons. This converter uses US fluid ounces and US gallons where specified.
Volume vs mass
Millilitres measure space. Grams measure mass. Water is close enough that 1 ml is about 1 g, but most ingredients are not water.
Container context
For containers, always allow room for headspace, shape and practical use. A theoretical conversion does not guarantee a container will be comfortable to fill.
Best workflow
Choose the source system first, then convert. Do not combine Australian spoons, US cups and metric labels unless you are deliberately adapting the recipe.
Why Australian, US and UK measures disagree
An Australian metric cup is 250 mL and an Australian tablespoon is 20 mL. A US customary cup is approximately 236.588 mL; a typical US tablespoon is approximately 14.787 mL. The difference is small for some recipes and substantial when the recipe calls for several tablespoons.
| Measure | Millilitres |
|---|---|
| Australian metric cup | 250 mL |
| US customary cup | about 236.6 mL |
| Australian tablespoon | 20 mL |
| US tablespoon | about 14.8 mL |
| Metric teaspoon | 5 mL |
| US liquid gallon | 3,785.411784 mL |
| Imperial gallon | 4,546.09 mL |
When converting an overseas recipe, confirm which measures the author uses instead of relying only on the words “cup”, “tablespoon” or “gallon”.
Worked cooking example: adapting US cups
A US recipe calling for 1½ US customary cups of liquid uses approximately 1.5 × 236.588 = 354.9 mL. Pouring 1½ Australian metric cups instead would give 375 mL, around 20 mL more.
If a recipe uses 2 US tablespoons, that is roughly 29.6 mL; 2 Australian tablespoons would be 40 mL. This is why switching the measuring spoon system can alter a sauce or baking recipe.
These are volume conversions; ingredient density is a separate issue. For flour, sugar or oil, grams cannot be inferred reliably from mL without ingredient-specific data.
What to round and when
Use precise factors to calculate, then round to the resolution of the equipment. A marked 5 mL kitchen spoon does not justify reporting a recipe volume to four decimal places. A container marked only “approximately 2 litres” should not be treated as a calibrated vessel.
For standard metric volume: 1 L = 1,000 mL, 1 m³ = 1,000 L. For US liquid units: 1 US gallon = 3.785411784 L. For imperial liquid gallons: 1 imperial gallon = 4.54609 L.
Choose the converter that matches the question
- Australian cups to mL and mL to Australian cups for recipes.
- Metric teaspoons to mL and Tablespoons to mL for cooking quantities.
- US gallons to litres and Litres to US gallons for imported products.
- Volume converter for different volume units.
Converting volume does not establish usable container capacity: check fill markings and manufacturer guidance, particularly for pressurised or hazardous liquids.
Before you act on the result
Use this volume conversion guide checklist before treating the result as reliable enough for a real decision.
- Write down the source value and exact unit.
- Confirm metric, US customary or imperial definitions.
- Apply the full conversion factor before rounding.
- Keep enough precision for the real task and label the final unit.
Sources and review notes
The sources below were selected for Volume Conversion Guide because they define the relevant measurement, rule or evidence base.
- National Measurement Institute — Australia’s National Measurement Institute maintains Australia’s measurement system and primary measurement standards. Use official measurement standards where legal, trade or technical precision matters.