Question 1

US gallon vs UK gallon?

Accepted Answer

A US gallon is 3.785 liters (231 cubic inches) while an Imperial (UK) gallon is 4.546 liters (277.4 cubic inches). The UK gallon is about 20% larger than the US gallon. This difference means that US MPG ratings cannot be directly compared to UK MPG ratings without conversion.

Question 2

How many cups in a liter?

Accepted Answer

One liter equals approximately 4.227 US cups. One US cup is exactly 236.588 mL (close to 240 mL in practice). In most recipes, 4 cups is used as an approximation for 1 liter, though technically it is slightly less.

Question 3

What is the difference between US and Imperial volume measures?

Accepted Answer

Despite sharing names, US and UK units differ. US fluid ounce = 29.57 mL; UK fluid ounce = 28.41 mL. US cup = 236.6 mL; UK cup = 284.1 mL (traditional) or 250 mL (metric). US pint = 473.2 mL; UK pint = 568.3 mL. US gallon = 3.785 L; UK gallon = 4.546 L. This is critical for cooking: a UK recipe calling for 1 pint means 568 mL, not 473 mL. Always check which system a recipe uses.

Question 4

How do I convert litres to US gallons?

Accepted Answer

1 US gallon = 3.78541 litres. 1 litre = 0.264 US gallons. Approximation: 4 litres ≈ 1 US gallon. Fuel economy conversion: mpg (US) × 0.425 = km/L. km/L × 2.352 = mpg (US). Note: UK uses miles per gallon with the larger UK gallon — 30 UK mpg ≈ 25 US mpg. Always specify US or UK when comparing fuel economy between different sources.

Question 5

How does volume relate to weight for common liquids?

Accepted Answer

1 litre of water = 1 kg at 4°C (by definition). 1 mL of water = 1 gram. Other liquids: milk ~1.03 kg/L, olive oil ~0.91 kg/L, honey ~1.42 kg/L, ethanol ~0.789 kg/L, petrol ~0.72 kg/L. For cooking, volume measurements convert to weight based on density — 1 cup of flour ≈ 125g (much less than the 240g of water in 1 cup). Baking is more accurate with weight than volume.

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