Rectangular Prism Volume Calculator
The volume of a rectangular prism is V = length × width × height, and this rectangular prism volume calculator multiplies your three sides the moment you type them. You'll get the answer at once in cubic inches or feet, liters, and gallons, plus the surface area, the base area, and the space diagonal. A rectangular prism is also called a cuboid, and the calculator shows its formula and steps with every result.
- Length × width × height
- Cuboid or box
- Surface area too
- Base & diagonal
- 14 output units
Last updated June 15, 2026 Method: V = l × w × h Reviewed by the Calcowa math team
Enter a positive length, width, and height to see the volume.
Show all units
V = 4 × 3 × 2 = 24 in³
What is a rectangular prism?
A rectangular prism is a solid box shape with six rectangular faces and a right angle at every corner. It's also called a cuboid, and everyday examples include a brick, a cereal box, a shipping crate, and most rooms. Its size is set by three measurements you'll recognize: length, width, and height.
When all three sides are equal, the rectangular prism becomes a cube. When just the base is square, it's a square prism. The volume rule stays the same for all of them, so you'll multiply the three sides whichever one you've got.
How do you find the volume of a rectangular prism?
To find the volume of a rectangular prism, multiply the three side lengths together. Here's the full sequence:
- 1
Measure the three sidesMeasure the length, width, and height, all in the same unit.
- 2
Multiply length by widthMultiply the length by the width to get the base area.
- 3
Multiply by the heightMultiply that base area by the height to get the volume.
- 4
Convert the unitsConvert to liters, gallons, or cubic feet if that's what you need.
Properties and net of a rectangular prism
A rectangular prism has 6 faces, 12 edges, and 8 vertices. The six faces are rectangles in three matching pairs, the twelve edges meet at right angles, and the eight vertices are the corners. Unfold the box flat and you've got its net: six rectangles joined along their edges, the shape you'd cut from card to build one.
Surface area, base, and lateral area
The volume fills the inside, but a box has a few area measures too. The base area is length × width, the spot the prism sits on. The lateral area is the four side walls without the top and bottom, 2(l + w) × h. The total surface area adds all six faces, SA = 2(lw + lh + wh). This calculator shows the surface area, base, and space diagonal alongside the volume, so you'll see them all at a glance, and the rectangular prism surface area calculator breaks the faces down in full.
Rectangular prism, cube, and square prism
These three shapes are close cousins. A cube is a rectangular prism with all three sides equal, so its volume is s³. A square prism has a square base and a different height, so its volume is s²h. A general rectangular prism, or cuboid, has three different sides and uses l × w × h. The difference between a cube and a cuboid is simply whether all the sides match. They're one family with one volume rule.
A rectangular prism volume example
Say you've got a storage box that's 30 cm long, 20 cm wide, and 15 cm tall. Multiply the length by the width for a base area of 600 square centimeters, then multiply by the height of 15.
V = 30 × 20 × 15 = 9,000 cm³
that's 9 liters, or about 2.38 US gallons
Type 30, 20, and 15 in centimeters above, and you'll get the matching liters and gallons without converting by hand.
Units and accuracy
Calcowa shows the rectangular prism volume in liters, US and UK gallons, milliliters, fluid ounces, and cubic mm, cm, m, inches, feet, and yards all at once. Enter your three sides in any of the supported units, and the conversions are exact, so the results suit shipping, storage, aquariums, and school work alike.
| Unit | Best for | Good to know |
|---|---|---|
| Cubic inches (in³) | Boxes, parcels, small containers | Default when you enter inches |
| Cubic feet (ft³) | Rooms, fridges, shipping crates | 1 ft³ = 1,728 in³ |
| Liters (L) | Tanks, aquariums, storage bins | 1 L = 1,000 mL |
| US gallons (gal) | Water tanks and containers | 1 US gallon = 3.785 L |
| Cubic yards (yd³) | Concrete, soil, large fills | 1 yd³ = 27 ft³ |
Frequently asked questions
Is a rectangular prism the same as a box?
Pretty much. An ordinary box, a cuboid, and a rectangular prism all mean the same six-sided shape with rectangular faces and right-angle corners. The volume of any of them is length times width times height.
The volume of a rectangular prism is V = length × width × height, so you just multiply the three side lengths. For a box that's 4 by 3 by 2 inches, the volume is 4 × 3 × 2 = 24 cubic inches.
A rectangular prism has 6 faces, 12 edges, and 8 vertices (corners). The faces come in three matching pairs, opposite sides are equal, and every corner is a right angle.
Yes. Cuboid is just another name for a rectangular prism, common in the UK and in math class. Both mean a box shape with six rectangular faces and right angles at every corner.
The base is one of the rectangular faces, and its area is length × width. If you know the volume and the height, you can also work back to the base area with base = volume ÷ height.
Multiply length × width × height to get the volume in cubic units, then read the litres or gallons line. The calculator shows litres, US and UK gallons, and millilitres next to the cubic result, so there's no manual conversion.
A square prism has a square base, so two of its sides are equal: V = side × side × height, or s²h. Enter the same length and width in the calculator and you've got a square prism.
Add up all six faces: SA = 2(lw + lh + wh). This calculator shows the surface area next to the volume, and our rectangular prism surface area tool covers it in full.
Related calculators
Need the surface area, or a different solid? These geometry tools pair well with rectangular prism volume.
All six faces of the same box.
Cylinder volumeVolume of a round container.
Cube volumeA prism with all sides equal.
Need a box volume fast?
Try the calculator above, or browse every shape in the geometry hub.