Are US and UK gallons the same?

No. 1 US gallon = 3.785 L. 1 UK (Imperial) gallon = 4.546 L. Always check which standard a recipe or fuel listing uses.

How many millilitres in a US fluid ounce?

29.5735 mL (rounded to 29.57). The UK fluid ounce is 28.4131 mL.

🔄 Conversion

Volume Converter

Convert liquid and dry volumes — litres, millilitres, US gallons, UK gallons, cubic metres, cubic feet, pints, cups. Note the US gallon (3.785 L) is smaller than the UK gallon (4.546 L).

Last reviewed: January 2026 Formula shown No signup required

Educational estimate. Calculator results are for planning and information only, not financial, tax, medical, legal, or engineering advice. Verify important decisions with official sources or a qualified professional.

Volume Converter

Litres, Gallons (US/UK), Cubic Metres, Pints

Value to Convert

Enter any number (decimals allowed).

From

📐 Formula & Method

Linear conversion

result = value × (factor_from / factor_to)

All units are stored as a multiplier against an internal base unit. To convert, the input is first scaled to the base, then divided by the target factor.

📋 How to Use

1
Enter the numeric value you want to convert.
2
Pick the source unit in the From dropdown.
3
Pick the target unit in the To dropdown.
4
Click Calculate. You will see the result, a full conversion table to every supported unit, and a list of common conversions.

💡 Key Insights

1 US gallon = 3.785 litres; 1 UK gallon = 4.546 litres. The UK gallon is about 20% larger.
1 litre = 1,000 cm³ = 1 dm³ — the SI definition by volume.
Cooking: 1 US cup = 240 ml (US legal nutrition labelling); 1 UK cup ≈ 284 ml (the rare imperial cup) — most modern UK recipes use ml directly.
US fl oz vs UK fl oz differ by 4% — never assume they are equal in cocktail or pharmacy recipes.

🔬 Methodology & Accuracy

Formula: Linear unit conversion with high-precision constants. All math runs client-side in your browser using IEEE-754 doubles.

Data sources: BIPM SI brochure (9th ed.); NIST SP 811 (2008 ed.); ISO 80000-1 quantities and units.

Last reviewed: January 2026 · Accuracy: Results are precise to two decimal places using IEEE-754 double-precision arithmetic. Intended for educational and planning use only.

For informational purposes only. Results are estimates based on the inputs and formulas provided. For financial, tax, medical, or legal decisions, consult a qualified professional. Rates and regulations change — always verify current figures with official sources.

Accuracy & Feedback

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❓ Frequently Asked Questions

🧭 Next Steps

Complete your Conversion picture

These tools naturally pair with the Volume Converter — use them in order to get a full view.

Cooking Converter

Convert recipe quantities between US/UK/metric.

Weight Converter

Many recipes mix weight (grams) with volume (cups) — convert both.