Units & Conversion · 升与加仑（Liter & Gallon） · Updated 2026-10-25
What Is Liter & Gallon?
Definition
Two gallons coexist: US (3.785 L) and imperial (4.546 L). US pumps and MPG use the US gallon; UK MPG uses imperial. One US gallon = 4 quarts = 8 pints. The "5-gallon" water cooler bottle is 18.9 L US. Fuel figures: the US quotes MPG (miles per US gallon), China uses L/100km — convert via L/100km = 235.2 ÷ MPG.
Formula
1 US gal = 3.785 L; 1 Imp gal = 4.546 L; L/100km = 235.2 / MPG(US)
Worked Example
A 30 MPG rating means ~7.8 L/100km with US gallons but ~9.4 L/100km with imperial — same number, 20% apart.
Common Misconception
"A gallon is universal" — US and imperial differ 20%; half the glow of UK MPG figures comes from the bigger gallon. And the office water-cooler "5-gallon" bottle is US 18.9 L, not 22.7 L imperial.
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