Craft Quantities
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Measurements & Conversions

Litres to Imperial Gallons Calculator

Convert litres into UK imperial gallons to check a metric volume against a British rating plate.

  • Answers as you type
  • Every formula cited
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SettingsSettings for this calculationUS
Market
Imperial · sales tax
The volume in litres.

A cubic metre is 1000 litres, so a tank quoted at 2.5 m³ is 2500 L. For a rectangular vessel measured in metres, length × width × depth × 1000 gives litres directly.

Volume

220 imp gal

High confidence

1 L = 1 / 4.54609 ≈ 0.219969 imperial gallons, from the exact 1985 definition. Exact by definition. A UK gallon is not a US gallon — check which the target figure uses.

Same volume in US gallons
264.17 US gal
Same volume in cubic metres
1 m³
Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

  • Weights and Measures Act 1985 (UK): 1 imperial gallon = 4.54609 litres exactly

Inputs used

Volume (L)
1000

Intermediate steps

Same volume in US gallons
264.17 US gal
Same volume in cubic metres
1 m³
Final result219.97 imp gal

Confidence note: 1 L = 1 / 4.54609 ≈ 0.219969 imperial gallons, from the exact 1985 definition. Exact by definition. A UK gallon is not a US gallon — check which the target figure uses.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-09-11 · v1.0.0

Regulatory standards & verification citations1
  1. Weights and Measures Act 1985 (UK): 1 imperial gallon = 4.54609 litres exactly
Cite this page

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Metric volumes are what modern equipment is specified in and imperial gallons are what a great deal of installed British plant is labelled with, so this conversion is mostly used to check a new number against an old plate. That is a comparison worth doing carefully, because two things can go wrong at once: the plate may be quoting the US gallon rather than the imperial one, and it may be quoting brim-full capacity rather than the working volume set by an overflow. Neither is visible in the arithmetic. Convert the litres, then satisfy yourself that the gallon you are comparing against is the same gallon and describes the same part of the vessel.

How to calculate litres to imperial gallons in 2 steps

  1. Volume (L)The volume in litres.
  2. VolumeThe tool computes the volume from those figures and shows the formula, its sources, and a confidence rating alongside it.

Litres to Imperial Gallons at common values

Page defaults, not your figures above.

Volume (L)Volume (imp gal)
10022
20044
500110
1,000220
2,000440
5,0001,100
10,0002,200

Frequently asked questions

Is there a quick mental version?
A litre is a shade over a fifth of an imperial gallon, so divide by five and take a little off. 1000 litres is 220 gallons, near enough 200 by the rough rule and 219.97 exactly. The rough version is fine for judging whether a vessel is in the right range and no use at all for a capacity that has to be stated.
Which gallon does a miles-per-gallon figure use?
In the UK, the imperial one — which is why UK and US mpg figures for the same vehicle differ by about twenty percent, with the UK number always the flattering one. Converting litres per hundred kilometres to mpg without fixing which gallon is meant produces a number that is wrong by that same fifth.
Does this help with a rainwater butt or storage tank?
For reading the rating, yes. Sizing is a different calculation — it depends on roof area, local rainfall and how much demand you intend the store to meet, and a tank sized by gut feel is usually either far too small to bridge a dry spell or large enough to stand half empty all year.
Why do some UK documents still use gallons at all?
Because the installed base does. Water byelaw guidance, older building services drawings and the plates on decades-old cisterns predate metrication, and replacing the paperwork is nobody's priority while the equipment still works. The unit survives in the documentation long after it has left the price list.
Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.