volume calculator
Calculate the volume of any rectangular space in cubic feet, cubic yards, gallons, and liters from length, width, and height in feet.
Volume tells you how much space a rectangular area holds — the number you need before ordering concrete, gravel, mulch, or water. Enter length, width, and height in feet and get the result in every unit a supplier might quote: cubic feet, cubic yards, gallons, and liters.
How this calculator works
A rectangular volume is length times width times height. From there, cubic feet converts to the other units with fixed factors.
Formula: Cubic feet = L × W × H. Cubic yards = ft³ ÷ 27. Gallons = ft³ × 7.48052. Liters = ft³ × 28.3168.
Worked example
A space 10 ft long, 8 ft wide, and 6 ft deep:
- Cubic feet: 10 × 8 × 6 = 480.00 ft³
- Cubic yards: 480 ÷ 27 ≈ 17.778 yd³
- Gallons: 480 × 7.48052 ≈ 3590.6 gal
- Liters: 480 × 28.3168 ≈ 13592.1 L
Reference
| L × W × H (ft) | Cubic feet | Cubic yards |
|---|---|---|
| 5 × 5 × 2 | 50.00 ft³ | 1.852 yd³ |
| 10 × 8 × 6 | 480.00 ft³ | 17.778 yd³ |
| 20 × 10 × 4 | 800.00 ft³ | 29.630 yd³ |
How to measure
Measure the inside length and width of the space, then the depth or height straight down from the top edge to the bottom. This works for footings, raised planter beds, storage bins, and excavation pits — anywhere the sides are roughly straight. For a round tank or cylinder, use the Cylinder Volume Calculator instead, since a box formula overstates a round shape’s true volume.
Frequently asked questions
What's the formula for volume?
For any rectangular space, volume equals length times width times height: V = L × W × H. Keep all three measurements in feet and the result comes out directly in cubic feet.
How do I convert cubic feet to cubic yards?
Divide cubic feet by 27, since a cubic yard is 3 ft × 3 ft × 3 ft = 27 cubic feet. This calculator does that division for you alongside the gallon and liter conversions.
Why does the calculator show gallons if I'm not filling anything with liquid?
Gallons and liters are useful even for dry volume, since some suppliers (concrete, water features, chemical mixes) quote by liquid measure. If you only need dry volume, use the cubic feet or cubic yards figures.
My height or depth is in inches, not feet — what do I do?
Divide the inch measurement by 12 before entering it. A 6-inch slab depth becomes 0.5 ft; a 4-inch depth becomes 0.333 ft.
Does this work for a shape that isn't a rectangular box?
No — this tool assumes straight sides and a flat top and bottom, like a footing, planter, or storage bin. For round tanks or piles use the Cylinder Volume, Cone Volume, or Sphere Volume calculators instead.
How accurate is this for ordering material?
It's exact for the geometric volume you enter. Add your own waste margin (5–10% is typical for concrete and fill) since real excavations and forms are rarely perfectly square.
Estimates only. Verify quantities with your supplier before purchasing.