Gallons to Cubic Feet Converter

In‑depth guide: gallons to cubic feet

This calculator converts volume between gallons and cubic feet with accuracy suitable for engineering estimates, building take‑offs, and lab prep. One cubic foot (ft³) is exactly 1,728 cubic inches, so once a gallon definition is known, the conversion is straightforward multiplication by a constant “factor.” The app supports the three commonly encountered gallon systems—US liquid, US dry, and Imperial—because tank ratings, product specs, and regulatory documents may use any of them depending on industry and geography.

Definitions and math

The US liquid gallon is defined as exactly 231 in³. Therefore 1 US liquid gallon equals 231 ÷ 1728 = 0.1336805556 ft³, and 1 ft³ equals 1728 ÷ 231 ≈ 7.480519 US liquid gallons. The US dry gallon is defined as 268.8025 in³, producing a factor of 0.1555570023 ft³ per dry gallon. The Imperial gallon is anchored to liters: 1 imp gal = 4.54609 L and 1 L = 0.0353146667 ft³, so each Imperial gallon is about 0.1605436532 ft³. The calculator chooses the correct factor automatically from the selector and keeps both directions in sync.

Picking the right gallon

Use US liquid for most American plumbing, fuel, beverage, and consumer packaging contexts. Choose US dry for certain agricultural commodities and historical US standards. Select Imperial for UK and some Commonwealth usage, older British equipment, and technical literature referencing imperial capacities. If a spec sheet simply says “gallons” without context but comes from a US manufacturer, assume US liquid unless there is an explicit dry or imperial note.

Precision, rounding, and readability

Decimals let you tune the number of places shown; they do not change the underlying math. Half‑up rounding is the everyday rule most people expect, while half‑even (bankers) rounding is useful when aggregating many rows and you want unbiased totals. Thousands separators improve readability in large batch conversions and reports without affecting numerical accuracy.

Workflow boosters

The batch area processes one value per line or the first column of a CSV, producing a clean table you can export as CSV for spreadsheets or print to PDF for sign‑off. The scenario manager stores named snapshots—system, precision, rounding, and results—so you can recall client options, compare variants side by side, and include them in proposals. The copy‑link button generates a permalink with your selections encoded, making it easy to share a reproducible calculation state with teammates.

Sanity checks

A quick way to confirm you are on the correct system is to test a familiar size. For example, a 55‑gallon drum (US liquid) should read roughly 7.3524 ft³. A 10‑gallon aquarium reads 1.3368 ft³. If your numbers are meaningfully different, double‑check that you did not select Imperial or US dry by mistake and verify the decimal and rounding settings.

Finally, remember that the converter also presents liters, cubic meters, and cubic inches for quick cross‑checks against international documentation. With accurate constants, careful rounding options, and exportable outputs, this single‑file tool is built to drop into your workflow and remove the friction from everyday volume conversions.