Cubic Inch Formula
Volume (in³) = Length (in) × Width (in) × Height (in)
To ft³: in³ ÷ 1,728
To litres: in³ × 0.016387
To US gallons: in³ ÷ 231
To ft³: in³ ÷ 1,728
To litres: in³ × 0.016387
To US gallons: in³ ÷ 231
Example: A storage drawer 24" long × 18" wide × 6" deep = 24 × 18 × 6 = 2,592 in³ = 1.5 ft³ = 42.5 litres
Common Home Uses for Cubic Inch Calculations
| Application | What You Calculate | Why It Matters |
|---|---|---|
| Aquarium / Fish Tank | Tank L × W × H (in) | Water volume in gallons (÷231) |
| DIY Storage / Drawers | Compartment dimensions | Check if items fit, organise space |
| Packaging / Gift Boxes | Box L × W × H (in) | Find right box size for contents |
| Engine Displacement | Bore² × stroke × cylinders × 0.7854 | cc to in³ (1 in³ = 16.387 cc) |
| Speaker Enclosure | Internal box dimensions | Match volume to sub specifications |
| Planter / Pot Volume | Pot interior L × W × H | How much potting mix to buy |
Aquarium Volume Quick Reference
Fish tanks are commonly measured in gallons (US). Use the formula: in³ ÷ 231 = US gallons
| Tank Size (L × W × H inches) | in³ | US Gallons |
|---|---|---|
| 20 × 10 × 12 | 2,400 | 10 gal |
| 24 × 12 × 16 | 4,608 | 20 gal |
| 30 × 12 × 18 | 6,480 | 29 gal (long) |
| 36 × 18 × 16 | 10,368 | 55 gal |
| 48 × 18 × 21 | 18,144 | 75 gal |
Frequently Asked Questions
1 US gallon = 231 cubic inches exactly. This is the standard conversion used for aquariums, containers and liquid measurement. To convert in³ to gallons, divide by 231. For UK imperial gallons, 1 UK gallon = 277.42 in³.
Multiply each dimension in cm by 0.3937 to get inches first, then calculate L × W × H in inches. Or switch the unit selector in this calculator to "cm" — it will automatically display results in in³.
1 cubic foot = 1,728 cubic inches (12 × 12 × 12 = 1,728). To convert in³ to ft³, divide by 1,728. This calculator shows both values automatically.