Imperial gallon to Cubic inch

imp gal

1 imp gal

in³

277.4194327904711911786 in³

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Quick Reference Table (Imperial gallon to Cubic inch)

Imperial gallon (imp gal)Cubic inch (in³)
0.5138.7097163952355955893
1277.4194327904711911786
2554.83886558094238235721
51,387.09716395235595589301
102,774.19432790471191178603
5013,870.97163952355955893014

About Imperial gallon (imp gal)

The imperial gallon is a unit of volume defined as exactly 4.54609 liters, used in the United Kingdom, Canada, and some Commonwealth nations. It is approximately 20% larger than the US liquid gallon. Fuel economy in the UK is expressed in miles per imperial gallon. The imperial gallon divides into 8 imperial pints, each of 568 mL. The UK officially metricated fuel sales to liters in the 1980s–1990s, but miles per imperial gallon remains the legal unit for new car fuel economy labels.

UK car fuel economy figures are expressed in miles per imperial gallon. One imperial gallon equals 8 standard UK pints of beer.

About Cubic inch (in³)

A cubic inch (in³) is the volume of a cube with 1-inch sides, equal to approximately 16.387 milliliters. In the US, it is used for engine displacement (the classic Chevrolet 350 = 350 in³ ≈ 5.7 L), small container volumes, and pharmaceutical packaging. Car engine displacement was historically described in cubic inches before the automotive industry switched to liters in the 1980s–1990s. The unit also appears in 3D printing and medical device specifications.

A classic Chevy 350 V8 engine displaces 350 in³ (≈ 5.7 L). A standard tennis ball has a volume of about 15 in³.


Imperial gallon – Frequently Asked Questions

One imperial gallon is defined as exactly 4.54609 liters — approximately 20% more than the US liquid gallon (3.785 L).

The UK switched fuel sales to liters in the 1990s. However, miles per gallon (imperial) remains the legal unit for car fuel economy on new vehicle labels. Road speed is in mph and distances are in miles, so imperial gallons remain embedded in UK motoring.

UK MPG uses the imperial gallon (4.546 L); US MPG uses the US gallon (3.785 L). Multiply UK MPG by 0.832 to get US MPG. A car rated 40 UK MPG ≈ 33 US MPG.

There are exactly 8 imperial pints in one imperial gallon. Each imperial pint is 568 mL, compared to 473 mL for a US pint.

Canada officially metricated in the 1970s and fuel is sold in liters. However, some older Canadians and certain agricultural contexts still reference imperial gallons informally. Canadian and UK imperial gallons are identical (4.54609 L).

Cubic inch – Frequently Asked Questions

One cubic inch equals approximately 16.387 mL. This follows from 1 inch = 2.54 cm, so 1 in³ = 2.54³ cm³ = 16.387 cm³ = 16.387 mL.

American car engines were historically described in cubic inches of displacement. The 350, 427, and 454 in³ engines are iconic V8 ratings. Most manufacturers switched to liters in the 1980s–1990s, but cubic inches remain part of classic car culture.

One liter equals approximately 61.024 cubic inches. A 350 in³ engine is approximately 5.74 liters.

Cubic inches are still used in the US for motorcycle and small engine displacement, small packaging volumes, and some industrial contexts. 3D printer filament usage is sometimes estimated in cubic inches.

One US fluid ounce equals approximately 1.805 cubic inches. One cubic inch equals about 0.554 US fluid ounces. These conversions are used in packaging design and liquid container manufacturing.

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