21 liters to US gallons
5.55 gal
21 L = 5.55 gal, or 1 gal 1.55 qt.
US gallons
5.55gal
21 L = 5.55 gal
The short answer
How many US gallons is 21 liters?
21 L = 5.55 gal, which reads as 1 gal 1.55 qt. 1 liter = 0.264172 US gallons, so the working is 21 × 0.264172 = 5.55.
The working
The factor below is an exact definition rather than a measurement, so nothing is approximated in the arithmetic. The only rounding on this page happens where a number is displayed.
1 liter = 0.264172 US gallons 21 × 0.264172 = 5.55
21 liters as 1 gal 1.55 qt
A decimal is the right form for a spreadsheet and the wrong one for almost everything else. Split into whole units, 21 L is 1 gal 1.55 qt — the reading you would actually give someone, and the one a tape measure, a scale, or a timetable is marked in.
How much precision do you need?
Each row is the same answer cut at a different number of decimals, with what that choice costs you. Pick the shortest row whose error is smaller than whatever you are measuring with.
| Rounded to | Answer (gal) | Off by |
|---|---|---|
| Whole number | 6 | +0.45239 |
| 1 decimal | 5.5 | −0.04761 |
| 2 decimals | 5.55 | +0.00239 |
Round trip: take 5.55 gal back the other way and you land on 21.0090 L — a drift of 0.0090 L. That gap is the rounding, not the conversion.
What 21 L looks like
20 L
The NATO-pattern steel jerrycan holds 20 litres, the middle size in a range that also runs 5 and 10 litres.
Frequently asked questions
What is 21 liters in US gallons?
21 liters is 5.55 US gallons. 1 liter = 0.264172 US gallons, so the working is 21 × 0.264172 = 5.55.
What is 21 liters in gallons and quarts?
1 gal 1.55 qt. A decimal answer such as 5.55 gal is the right shape for a form field or a spreadsheet, but the compound form is what a tape measure, a scale, or a schedule actually reads.
How accurate is 5.55 gal?
Rounding to 5.55 gal and converting straight back gives 21.0090 L, a drift of 0.0090 L from the 21 you started with. The factor itself is exact; every bit of that difference comes from the rounding, not the conversion.
Nearby values
Any value at all
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