volume calculator
A volume calculator multiplies length × width × height for cubic feet, then ÷ 27 for cubic yards: a 10 × 8 × 6 ft space is 480 ft³, or 17.78 yd³.
Volume calculator: how to get cubic feet and cubic yards
To use a volume calculator for a box-shaped space, multiply length by width by height, all in feet, to get cubic feet. Divide by 27 to get cubic yards. This page does both steps at once and also shows gallons and liters, so you can compare a concrete quote in yards with a water or chemical dose in gallons.
It fits anything with straight sides and a flat bottom: a footing trench, a raised planter, a storage bin, a sandbox, or an excavated pit.
The formula in plain words
Think of filling the space with 1-foot cubes. Length tells you how many cubes fit in a row. Width tells you how many rows fit side by side. Height tells you how many layers stack up. Multiply the three counts and you have the total.
- Cubic feet = length × width × height
- Cubic yards = cubic feet ÷ 27
- Gallons = cubic feet × 7.48052
- Liters = gallons × 3.78541
The calculator adds no waste to what you enter.
Worked examples
- Excavation pit, 10 ft × 8 ft × 6 ft deep
- Cubic feet: 10 × 8 × 6 = 480 ft³
- Cubic yards: 480 ÷ 27 = 17.778 yd³
- Gallons: 480 × 7.48052 = 3,590.6 gal
- Liters: 13,592.1 L
- Footing trench, 24 ft long × 2 ft wide × 1 ft deep
- Cubic feet: 24 × 2 × 1 = 48 ft³
- Cubic yards: 48 ÷ 27 = 1.778 yd³
- Gallons: 359.1 gal
In example 2 you are ordering under two yards, and many ready-mix suppliers charge extra for small loads, so ask about minimums before you commit.
Quick reference
| Length × Width × Height (ft) | Cubic feet | Cubic yards | Gallons |
|---|---|---|---|
| 5 × 5 × 2 | 50 | 1.852 | 374.0 |
| 8 × 4 × 2 (raised bed) | 64 | 2.370 | 478.8 |
| 12 × 4 × 0.5 (slab strip) | 24 | 0.889 | 179.5 |
| 10 × 8 × 6 | 480 | 17.778 | 3,590.6 |
| 20 × 10 × 4 | 800 | 29.630 | 5,984.4 |
How to measure
- Use inside dimensions. For a form, bin, or planter, measure the empty interior, not the outside of the boards.
- Measure depth straight down. Drop a tape or a level stick from the top edge to the floor of the space.
- Check both ends. A trench that runs downhill is deeper at one end. Measure depth at each end and enter the average.
- Convert inches first. Divide inches by 12 so every field is in feet.
- Split odd shapes. An L-shaped pit is two boxes. Run each one and add the cubic feet.
Common mistakes
- Mixing units. Length in feet and depth in inches gives a result off by a factor of 12.
- Using this tool for round things. A 4 ft round tank is not a 4 × 4 box. The box formula overstates it by about 27 percent, so use the cylinder volume calculator instead.
- Forgetting that dirt swells. Soil dug from a pit takes up more room as a loose pile than it did in the ground. Plan hauling for more than the pit volume.
- Ordering the exact number. Forms bow and subgrades dip. Add a margin before you place an order.
When the sides are not straight
Real holes rarely have vertical walls. If a pit is wider at the top than at the bottom, measure the length and width at both levels, then enter the average of each. This average-dimension method slightly overstates a sloped pit, so treat the answer as a ceiling.
A long excavation with a flat floor and sloped sides is closer to a trench. The trench volume calculator handles that shape directly, and your hauling plan should allow for dug soil swelling once it is loosened.
Where to go next
If the space is round and upright, such as a cistern or stock tank, the tank volume calculator gives gallons at any fill level. If you only need to convert a cubic-foot result into yards for a material order, the cubic yard calculator handles that, and the cylinder volume calculator covers columns and post holes.
Frequently asked questions
What's the formula for volume?
For any box-shaped 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. A 10 × 8 × 6 ft space is 480 ft³.
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. For example, 480 ft³ ÷ 27 = 17.78 yd³. 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. One cubic foot equals 7.48052 US gallons. 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, and a 4-inch depth becomes 0.333 ft. Entering 6 where 0.5 belongs makes the answer 12 times too large.
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.
Does the result include extra for waste?
No. It is the exact geometric volume of the numbers you enter, with no allowance added. Add your own margin, often 5 to 10 percent for concrete and fill, since real excavations and forms are rarely perfectly square.
Estimates only. Verify quantities with your supplier before purchasing.