To find cubic volume, multiply length x width x height after putting all three in the same unit. For example, a box 18 x 14 x 12 inches holds 3,024 cubic inches, which is 1.75 cubic feet. Then divide cubic feet by 27 for cubic yards, or multiply by 0.0283 for cubic meters.
Most people need a cubic number for something practical. Maybe a moving company wants to know how many cubic feet your furniture fills, or a shipping site asks for box dimensions. Perhaps the garden center sells soil by the cubic yard while your raised bed is measured in feet and inches. In every case, the math is the same short multiplication, and the only real trap is mixing units.
This guide focuses on the jobs where cubic volume actually costs you money: packing a truck, paying for a parcel, and ordering soil, gravel or concrete. First, you will see the formula. Next, you will work through worked examples with mixed inches and feet, and finally a chart for switching between cubic inches, feet, yards and meters.
In short: measure each side, convert all three numbers to one unit, multiply, and then convert the answer into the unit the seller or shipper uses. Because a cubic foot is 12 x 12 x 12 inches, there are 1,728 cubic inches in it, not 12. That single fact explains most wrong answers.
The conversion factors here follow the US National Institute of Standards and Technology. Its SI guide conversion table lists 1 cubic foot as 0.02831685 cubic meter and 1 cubic yard as 0.7645549 cubic meter. Both come straight from the exact definition of the inch as 25.4 mm.
Convert Each Measurement to One Unit First
Before you multiply anything, every side must use the same unit. So use this converter to turn inches into feet or yards, or centimeters into meters. Then multiply the three converted numbers.
The calculator handles one dimension at a time. For example, enter 30 inches and it returns 2.5 feet, which you can then multiply by the other two sides in feet.
Recommended Tools for Measuring Cubic Volume
A reliable tape measure covers boxes, furniture and garden beds. For rooms, garages and storage units, however, a laser distance measure is faster and easier to use alone, because it reads wall to wall without a helper holding the other end. Also look for a tape with a stiff blade and clear 1/16 inch marks, and a laser that can do area and volume in memory. The picks below come from established tool brands, based on manufacturer specs and buyer reports.
As an Amazon Associate, Measuring Expert earns from qualifying purchases.
Key Takeaways
- Cubic volume of a box or room = length x width x height, all in the same unit.
- 1 cubic foot = 1,728 cubic inches, and 1 cubic yard = 27 cubic feet.
- 1 cubic meter is about 35.31 cubic feet or 1.308 cubic yards.
- Movers and storage companies think in cubic feet; soil and concrete suppliers sell by the cubic yard.
- Carriers such as UPS turn box size into a billable “dimensional weight”.
- Convert depth in inches to feet before ordering soil or concrete; this is the most common mistake.
- Add a margin for waste and settling instead of ordering the exact number.
The Cubic Volume Formula in Plain Terms
A cubic unit is a cube whose sides are one unit long. So one cubic foot is a cube 1 foot on each side, and one cubic meter is a cube 1 meter on each side. The volume of a box-shaped space is simply how many of those cubes fit inside it.
Volume = length x width x height
For a rectangular box, the order does not matter, because multiplication gives the same result either way. What matters is that all three sides share one unit. As a result, the answer comes out in that unit “cubed”: inches give cubic inches, feet give cubic feet, and meters give cubic meters.
If you want the reason behind the cubes, our explainer on why volume is measured in cubic units walks through it with simple pictures in words. Similarly, for cylinders, cones and spheres, see how to find the volume of a solid.
| People often confuse | What is different |
|---|---|
| Square feet (sq ft) | Area: length x width only. A 10 x 12 ft floor is 120 sq ft. |
| Cubic feet (cu ft, ft³) | Volume: length x width x height. That same room with an 8 ft ceiling is 960 cu ft. |
| Linear feet | Length only, used for trim, fencing and lumber. |
| Cubic yard vs “yard” | Landscapers say “a yard of mulch” but mean one cubic yard, which is 27 cu ft. |
How to Calculate Cubic Volume When Units Are Mixed
Real measurements rarely come out tidy. A box might be 2 ft 6 in long, 18 in wide and 14 in deep. Here is a method that works every time:
- Measure each side at its widest point. Include handles, bulges and lids, since a carrier or a truck has to fit the whole thing.
- Write every value in one unit. For a box, inches are usually easiest: 2 ft 6 in becomes 30 in.
- Multiply the three numbers. 30 x 18 x 14 = 7,560 cubic inches.
- Convert to the unit you need. Divide cubic inches by 1,728 for cubic feet: 7,560 / 1,728 = 4.375 cu ft.
- Round only at the end. Keep the full number until the last step, then round to two decimals.
- Sanity-check the result. Ask whether the answer fits what you see; a small box should not come out at 40 cubic feet.
You can also convert to feet first: 2.5 ft x 1.5 ft x 1.1667 ft = 4.375 cu ft. Either path works, so pick the one with fewer fractions.
Cubic Feet for Moving, Storage and Shipping
Cubic feet is the everyday unit for anything that goes in a box, a truck or a storage unit. Here are three common situations.
Packing boxes and parcels
Take a box that measures 18 x 14 x 12 inches. First, 18 x 14 x 12 = 3,024 cubic inches. Next, 3,024 / 1,728 = 1.75 cubic feet, or roughly 49.6 liters. Moving boxes are often labeled by approximate cubic feet, so this check tells you whether a “small” box is really the size you expect.
Parcel carriers add one more step. As of October 2026, UPS explains on its dimensional weight page that it rounds each side to the nearest whole inch, multiplies them, and divides by 139 for daily rates or 166 for retail rates. It then bills the higher of actual weight and that dimensional weight. For the 18 x 14 x 12 box, 3,024 / 139 = 21.8, which rounds up to 22 lb, even if the contents weigh only 8 lb. Divisors change and differ by carrier, so check the current figure before you ship.
Storage units and rooms
A 10 x 10 ft storage unit with an 8 ft ceiling holds 10 x 10 x 8 = 800 cubic feet of space. In practice, you will not fill every inch, because boxes leave gaps and you need room to reach things. Similarly, a 12 x 10 ft bedroom with an 8 ft ceiling is 960 cu ft, or about 27.18 cubic meters.
Furniture for a moving estimate
Treat each large item as a box. Measure its overall length, depth and height, then multiply. A sofa 84 x 36 x 34 in, for example, works out to 102,816 cubic inches, or about 59.5 cubic feet. Add the items together to get a rough total for comparing truck sizes or quotes.
Cubic Yards for Soil, Mulch and Concrete
Bulk landscape materials and ready-mix concrete are sold by the cubic yard in the US. One cubic yard is a cube 3 ft on each side, so it equals 3 x 3 x 3 = 27 cubic feet. Therefore, the quickest route is to work in feet and divide by 27 at the end.
Raised garden bed
Say a bed is 8 ft long, 4 ft wide and 10 in deep. First, convert the depth: 10 / 12 = 0.833 ft. Then 8 x 4 x 0.833 = 26.67 cubic feet. Finally, 26.67 / 27 = 0.99 cubic yard. If you buy bagged soil in 2 cubic foot bags instead, you need 26.67 / 2 = 13.3, so buy 14 bags.
Concrete slab
A patio slab 10 x 12 ft and 4 in thick is 10 x 12 x 0.333 = 40 cubic feet. Next, 40 / 27 = 1.48 cubic yards. Many contractors then add roughly 5 to 10 percent for uneven ground and spillage; with 10 percent, that becomes about 1.63 cubic yards. For digging and grading jobs, our guide to cut and fill volumes covers sloped ground.
Metric Cubic Volume: Cubic Meters and Liters
Metric volume is simpler because every step is a power of ten. Measure in meters, multiply, and the answer is in cubic meters. For example, a crate 2.4 x 1.2 x 0.5 m holds 1.44 cubic meters, which is about 50.85 cubic feet or 1.88 cubic yards.
Smaller items are easier in centimeters. A box 40 x 30 x 25 cm is 30,000 cubic centimeters. Because 1,000 cubic centimeters equal 1 liter, that box holds 30 liters, or about 1.06 cubic feet. In addition, 1 cubic meter equals exactly 1,000 liters, which helps when you size water tanks or ponds. For a wider look at liters, gallons and the rest, see our overview of units of volume.
Cubic Volume Conversion Chart
These factors come from the exact inch (25.4 mm) and the US gallon (231 cubic inches), rounded for everyday use.
| From | Equals | Metric |
|---|---|---|
| 1 cubic inch | 1/1,728 cu ft | 16.39 cm³ (mL) |
| 1 cubic foot | 1,728 cu in; 7.48 US gal | 28.32 L; 0.02832 m³ |
| 1 cubic yard | 27 cu ft; 201.97 US gal | 764.55 L; 0.7646 m³ |
| 1 cubic meter | 35.31 cu ft; 1.308 cu yd | 1,000 L |
| 1 liter | 61.02 cu in; 0.0353 cu ft | 1,000 cm³ |
| 1 US gallon | 231 cu in; 0.1337 cu ft | 3.785 L |
Quick rules: cubic feet x 0.0283 = cubic meters; cubic meters x 35.31 = cubic feet; cubic feet / 27 = cubic yards; cubic yards x 0.7646 = cubic meters.
Cubic Volume of Rooms and Irregular Spaces
Few rooms are perfect boxes. However, you can still get a good number by splitting the space into rectangles. For an L-shaped room, measure it as two rectangles, find each volume, and add them. Likewise, for a closet or bump-out, calculate it separately and add it on.
Sloped ceilings need one extra step. If the ceiling rises evenly from 8 ft on one wall to 12 ft on the other, use the average height of 10 ft. Then multiply floor length x width x 10. Meanwhile, for round tanks, planters or post holes, use the cylinder formula instead (pi x radius squared x height), which the solid-volume guide linked above explains.
Do and Don’t
Do
- Convert all sides to one unit before multiplying.
- Measure at the widest point, including handles.
- Keep full decimals until the last step.
- Add a margin for waste, settling and gaps.
- Check which unit the seller or carrier uses.
Don’t
- Divide cubic inches by 12 to get cubic feet.
- Mix inches and feet in one multiplication.
- Confuse square feet of floor with cubic feet of space.
- Assume a “yard” of soil is a linear yard.
- Forget that carriers round box sides up.
Honest Limits of Cubic Volume Estimates
The formula is exact; the inputs are not. For one thing, a tape read to the nearest half inch on each side of a small box can shift the result by several percent. Soft or bulging boxes also measure differently from one person to the next. Loose materials add another layer: topsoil and mulch settle after watering, and gravel compacts under weight. As a result, the volume you calculate is the space to fill, not always the amount of material that ends up in it. Treat your number as a solid starting point, then add a reasonable margin.
When to Call a Professional
For a parcel or a garden bed, your own math is enough. On the other hand, structural concrete such as footings, foundations and driveways should involve a contractor or engineer, because thickness, reinforcement and base preparation matter as much as volume. Likewise, large earthmoving jobs often need a surveyor to measure grades. For an expensive move, a written in-home estimate from the mover protects you better than any calculator.
Frequently Asked Questions
What is cubic volume?
Cubic volume is the amount of three-dimensional space something fills, counted in cubes such as cubic inches, cubic feet or cubic meters.
How do I calculate cubic feet from inches?
Multiply length x width x height in inches, then divide by 1,728. For example, 18 x 14 x 12 in = 3,024 cubic inches = 1.75 cubic feet.
How many cubic feet are in a cubic yard?
There are 27 cubic feet in one cubic yard, because a cubic yard is 3 ft x 3 ft x 3 ft.
How do I find cubic volume with feet and inches mixed?
Convert every side to one unit first. Either change feet to inches and divide the result by 1,728, or change inches to decimal feet by dividing by 12.
How many cubic feet are in a cubic meter?
One cubic meter is about 35.31 cubic feet. To go the other way, multiply cubic feet by 0.0283.
How much soil do I need for a raised bed?
Multiply length x width x depth in feet and divide by 27 for cubic yards. An 8 x 4 ft bed 10 in deep needs about 26.7 cubic feet, or just under 1 cubic yard.
How do I calculate cubic volume for concrete?
Multiply length x width x thickness in feet, divide by 27, and add a small margin. A 10 x 12 ft slab 4 in thick is about 1.48 cubic yards before waste.
What is the difference between square feet and cubic feet?
Square feet measure flat area (length x width). Cubic feet measure space (length x width x height). A 120 sq ft room with an 8 ft ceiling is 960 cubic feet.
How many liters are in a cubic foot?
One cubic foot holds about 28.32 liters, or about 7.48 US gallons.
Does cubic volume change with the shape of the box?
The cubic volume formula L x W x H only works for box shapes. Cylinders, cones and spheres use their own formulas, though the answer is still in cubic units.
Cubic Volume: The Bottom Line
To sum up, cubic volume is length x width x height, with all three sides in the same unit. Divide cubic inches by 1,728 for cubic feet, divide cubic feet by 27 for cubic yards, and multiply cubic feet by 0.0283 for cubic meters.
So use cubic feet for boxes, rooms and moving estimates, and cubic yards for soil, mulch and concrete. Finally, convert inch measurements before you multiply, round only at the end, and add a sensible margin whenever you order material.
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