Imperial Gallon to Litre
Free instant imperial gallon to litre converter. 1 gal = 4.54609 L.
Common Imperial Gallon to Litre values
| Imperial Gallon (gal) | Litre (L) |
|---|---|
| 1 | 4.54609 |
| 5 | 22.7305 |
| 10 | 45.4609 |
| 25 | 113.652 |
| 50 | 227.305 |
| 100 | 454.609 |
| 500 | 2273.05 |
| 1000 | 4546.09 |
How does Imperial Gallon to Litre conversion work?
Type a value in the Imperial Gallon (gal) field and the equivalent in Litre (L) appears instantly to the right. The math uses the exact formula shown above — no rounding errors, no approximations beyond standard floating-point precision. Use the swap button to flip the units and see the inverse conversion.
Imperial Gallon. The UK and Commonwealth gallon. About 4.546 litres — 20% bigger than the US gallon.
Litre. The metric volume unit. About 1.06 US quarts; the volume of a 1 kg block of water.
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Conversion factors come from the official standard (NIST, BIPM, ISO definitions where applicable). Values are precise to standard floating-point limits.
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How it works — the formula
Volume scales as length cubed.
1 L = 1 dm³ = 0.001 m³ (exact)
1 US gallon = 3.785411784 L exactly
1 imperial gallon = 4.54609 L exactly (since 1985 redefinition)Volume is length cubed. The litre is a metric unit equal to one cubic decimetre. The US gallon (3.785411784 L) and imperial gallon (4.54609 L) differ by about 20%; US fluid measurements descend from the 1707 Queen Anne wine gallon, while imperial volumes were redefined in 1985 by the UK Weights and Measures Act in terms of the litre. US dry measurements (bushel, dry quart) form a separate system.
Worked examples
- Inputs:
- 1 US gal = ? L
- Output:
- 1 × 3.785411784 ≈ 3.7854 L
- Inputs:
- 1 UK gal = ? L
- Output:
- 1 × 4.54609 ≈ 4.5461 L (~20% larger than US gallon)
- Inputs:
- 2 cups (US) = ? mL
- Output:
- 2 × 236.5882365 ≈ 473.176 mL
Limitations
- US fluid ounce (29.5735296875 mL) ≠ UK fluid ounce (28.4130625 mL) ≠ avoirdupois weight ounce — all share the name "ounce".
- A "cup" varies: US legal cup is 240 mL, US customary cup is 236.5882365 mL, metric cup is 250 mL.
- Dry volumes (bushel, dry pint) follow a different scaling and are not interchangeable with fluid volumes.
- Gas-volume comparisons require pressure and temperature controls (STP, NTP, IUPAC) — pure unit conversion ignores those.
Conversions are exact rational arithmetic for SI ↔ US fluid ↔ imperial; cooking pages account for US-customary cup-size ambiguities by labelling "US cup" explicitly.