# Aquarium volume unit converter

> Type a volume in any unit — US gallons, liters, UK gallons, cubic inches, cubic feet, or cubic centimeters — and the other five convert live. 10 US gallons, for example, is 37.8541 L, 8.3267 UK gal, 2310 in³, 1.3368 ft³, and 37854.12 cm³.

Use the interactive converter on the page: https://petguidecalc.com/aquarium/volume-unit-converter/. Type a volume in any of the six units and the other five convert live.

## How do I convert between aquarium volume units?

Every unit is expressed as a factor to liters: 1 US gallon = 3.785412 L, 1 UK gallon = 4.54609 L, 1 cubic inch = 0.0163871 L, 1 cubic foot = 28.3168 L, and 1 cubic centimeter = 0.001 L. Type a value in any unit and the converter normalizes to liters, then re-derives the other five.

## 10 US gallons in every unit

| Unit | Value |
|---|---|
| US gallons | 10.0000 |
| Liters | 37.8541 |
| UK gallons | 8.3267 |
| Cubic inches | 2310 |
| Cubic feet | 1.3368 |
| Cubic centimeters | 37854.12 |

Conversion factors are NIST-exact: 1 US gal = 3.785411784 L = 231 in³; 1 UK gal = 4.54609 L.

## How the conversion works

The converter holds a single liter factor for each unit, so typing in any one input normalizes the value to liters and re-derives all six columns from that one figure — no rounding is applied until the display.

The US gallon and cubic-inch factors are statutory: 1 US gallon equals exactly 231 cubic inches, which is 3.785411784 liters. The UK (imperial) gallon is 4.54609 liters, about 20% larger than the US gallon.

Worked example from the calculator: 10 US gallons returns 37.8541 L, 8.3267 UK gal, 2310 in³, 1.3368 ft³, and 37854.12 cm³. Change any input and the other five update from the same shared formula.

## Unit conversion questions

**Q: Which units can this converter handle?**

Six: US gallons, liters, UK (imperial) gallons, cubic inches, cubic feet, and cubic centimeters. Type a value in any of the six fields and the other five re-derive live from the shared liter factor.

**Q: How do US and UK gallons differ?**

A US gallon is 3.785412 liters; a UK (imperial) gallon is 4.54609 liters. A UK gallon is about 1.201 US gallons — roughly 20% larger — so always pick the gallon type that matches your tank or product label.

**Q: How many cubic inches are in a US gallon?**

Exactly 231 cubic inches. That is the statutory definition in the US, and it is why the cubic-inch column is exact whenever you start from a whole number of US gallons.

**Q: Do I need to convert before using the shape volume calculators?**

No — the shape volume calculators accept centimeters or inches for the tank dimensions and convert internally. This converter is for water volumes and for comparing values that are already in different units.

**Q: Why does the site usually show US gallons?**

US gallons are the default tank-sizing unit across the English-language aquarium hobby. Liters are the metric standard and appear alongside, and UK gallons are included here so imperial users can convert without guessing.

## References

The conversion factors below are NIST-exact unit definitions; Lewis & Perkin provide the salinity-scale context used elsewhere on the site.

- [Guide for the Use of the International System of Units (SI) — Special Publication 811 (2008 Edition)](https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication811e2008.pdf) — Thompson A, Taylor BN, NIST Special Publication 811, 2008. Defines the liter–cubic-meter relationship and the US gallon ≈ 3.785412 L used by this converter.
- [NIST Handbook 44 — Appendix C: General Tables of Units of Measurement (2024 Edition)](https://www.nist.gov/document/nist-hb-44-2024-appendix-c-general-tables-units-measurement) — National Institute of Standards and Technology, NIST Handbook 44, 2024. Confirms 1 US gallon = 231 cubic inches exactly (statutory definition) — the anchor for the cubic-inch result.
- [The Practical Salinity Scale 1978: Conversion of Existing Data](https://www.vliz.be/imisdocs/publications/29449.pdf) — Lewis EL, Perkin RG, Limnology and Oceanography, 1981. Defines the Practical Salinity Scale 1978 (PSS-78), the background for the salinity-based volume references used across the aquarium calculators.

_Educational resource, not veterinary advice. PetGuideCalc — https://petguidecalc.com_