Convert Liters to Gallons: US, UK, Table and Consumption References

Converting liters to gallons has a trap: there isn’t a single gallon. The US gallon (3.785 L) and the imperial UK gallon (4.546 L) differ by ~20 %. Here you have the exact formulas, tables, mental tricks and references for tank, fuel economy, drinks and irrigation.

The critical difference: US vs UK (Imperial)

Gallon	Exact definition	Liters	Main use
US liquid gallon	231 in³	3.785411784 L	USA, Latin America, Philippines, South Korea
UK imperial gallon	4.54609 L (defined)	4.54609 L	UK, Ireland, Canada (historical), Anglophone Caribbean
US dry gallon	268.8025 in³	4.40488 L	Grain/agricultural (rarely used)

1 UK gallon = 1.20095 US gallons → ~20 % larger.
Always verify which gallon your source uses (country, “US gal” / “Imp gal” label).

Exact formulas

Liters → Gallons

• US: gal_US = L / 3.785411784
• UK: gal_UK = L / 4.54609

Gallons → Liters

• US: L = gal_US × 3.785411784
• UK: L = gal_UK × 4.54609

Reference table (Liters → US / UK Gallons)

Liters	Gal US	Gal UK	Context
1	0.264	0.220	Large glass
2	0.528	0.440	Soda bottle
3.785	1.000	0.833	1 US gallon
4.546	1.201	1.000	1 UK gallon
5	1.321	1.100	Water jug
10	2.642	2.200	—
20	5.283	4.400	Camping jerrycan
30	7.925	6.600	—
40	10.567	8.799	Large motorcycle tank
50	13.209	10.998	Small car tank
60	15.850	13.198	Medium car tank
70	18.492	15.398	Large car tank
80	21.134	17.597	—
100	26.417	21.997	Beer keg (1/2 US keg = 15.5 gal)
200	52.834	43.994	Small cistern

Mental tricks

Gallon	Approximation	Mental formula	Error
US	1 gal ≈ 3.8 L	gal ≈ L / 3.8	+0.4 %
UK	1 gal ≈ 4.5 L	gal ≈ L / 4.5	-1.0 %

Inverse:

• US: L ≈ gal × 3.8
• UK: L ≈ gal × 4.5

Fuel economy: L/100 km ↔ mpg

Conversion	Exact formula	Approximation
L/100 km → mpg US	mpg_US = 235.214583 / (L/100km)	≈ 235 / (L/100km)
L/100 km → mpg UK	mpg_UK = 282.480936 / (L/100km)	≈ 282 / (L/100km)
mpg US → L/100 km	L/100km = 235.214583 / mpg_US	≈ 235 / mpg_US
mpg UK → L/100 km	L/100km = 282.480936 / mpg_UK	≈ 282 / mpg_UK

Quick examples:

L/100 km	mpg US	mpg UK
4.0	58.8	70.6
5.0	47.0	56.5
6.0	39.2	47.1
7.0	33.6	40.4
8.0	29.4	35.3
10.0	23.5	28.2

Real-life references

Object / Situation	Liters	Gal US	Gal UK
Glass of water	0.25 L	0.066	0.055
Soda can	0.33 L	0.087	0.073
Wine bottle	0.75 L	0.198	0.165
Large water bottle	1.5 L	0.396	0.330
6-pack beer (355 ml each)	2.13 L	0.563	0.468
Motorcycle tank	12–18 L	3.2–4.8	2.6–4.0
Compact car tank	40–50 L	10.6–13.2	8.8–11.0
Family car tank	60–75 L	15.9–19.8	13.2–16.5
Beer keg (1/2 US keg)	58.7 L	15.5	12.9
Beer keg (1/4 US keg)	29.3 L	7.75	6.45
Garden watering (1h hose 15 L/min)	900 L	238	198
3 m inflatable pool	~3,000 L	~793	~660

Conclusion

• First: find out if it’s US gallon (3.785 L) or UK (4.546 L) — they differ by 20 %.
• Exact: divide L by 3.78541 (US) or 4.54609 (UK).
• Mental: L / 3.8 ≈ gal US; L / 4.5 ≈ gal UK.
• Fuel economy: mpg US = 235 / (L/100km); mpg UK = 282 / (L/100km).
• Tool: unit converter — pick “Volume” and the correct gallon.

Convert liters to gallons (US/UK) now.