Cubic Feet Calculator

Cubic Feet formula

Cubic inches = Length (in) x Width (in) x Height (in) x quantity
Cubic feet = Cubic inches / 1,728  (or Length (ft) x Width (ft) x Height (ft))
Cubic yards = Cubic feet / 27;  Gallons = Cubic feet x 7.48
Water weight (lb) = Cubic feet x 62.4

Worked example

Three storage totes, each 36 x 24 x 20 in: 36 x 24 x 20 = 17,280 cubic inches each. 17,280 / 1,728 = 10 cubic feet, so the three totes are 30 cubic feet, or 1.11 cubic yards. Filled with water they would hold 30 x 7.48 = 224.4 gallons and weigh 30 x 62.4 = 1,872 lb.

The same answer in feet: 3 ft x 2 ft x 1.667 ft = 10 cubic feet per tote. Switch the calculator to feet to enter dimensions that way; it multiplies by 12 behind the scenes.

Quick reference

How to calculate cubic feet

Cubic feet is length times width times height with all three in feet. Most things you measure are in inches, so multiply the three inch dimensions together for cubic inches and divide by 1,728, which is 12 x 12 x 12. A 24 x 18 x 12 inch box is 5,184 cubic inches, or 3 cubic feet. Converting each dimension to feet first (2 x 1.5 x 1) gives the same 3 cubic feet.

For mixed measurements such as 4 ft 6 in, convert to decimal feet (4.5) or to inches (54) before multiplying. For a cylinder such as a drum or tank, use radius squared times 3.1416 times height instead of length times width.

Where cubic feet show up

Moving companies and truck rentals size loads in cubic feet: a one-bedroom apartment is roughly 400 to 600 cubic feet of boxes and furniture, a three-bedroom house 1,200 to 1,800. Appliances are rated by interior capacity, which is smaller than the box they ship in, so measure the outside when planning truck or doorway space.

Shipping carriers charge by dimensional weight, which is cubic inches divided by a divisor such as 139, so a light but bulky 3 cubic foot box is billed as about 37 lb. Freezers, water heaters and aquariums are also sized in cubic feet or gallons; multiply cubic feet by 7.48 to move between the two.

Key facts

• One cubic foot is 1,728 cubic inches, 7.48 US gallons, 28.32 liters, or 0.037 cubic yards.
• A cubic foot of water weighs 62.4 lb, so a 40 gallon water heater holds about 334 lb of water.
• A medium moving box (18 x 18 x 16 in) is 3 cubic feet; a large box (18 x 18 x 24 in) is 4.5 cubic feet.
• Refrigerator and washer sizes are interior capacity: 20 to 25 cubic feet for a full-size fridge and 4 to 5 cubic feet for a washer drum.
• Rental trucks are rated by cargo volume: about 400 cubic feet for a 10 ft truck, 760 for a 15 ft truck and 1,700 for a 26 ft truck.

Frequently asked questions

Sources and references

• •Handbook 44 Appendix C, General Tables of Units of Measurement (cubic inches, cubic feet, cubic yards, gallons) (NIST)
• •Guide for the Use of the International System of Units, Appendix B.9 conversion factors (cubic foot, gallon, liter) (NIST)
• •Water Density (62.4 lb per cubic foot) (USGS)