cylinder volume calculator

How to find the volume of a cylinder

This cylinder volume calculator takes a diameter and a height in feet and applies V = π × (diameter ÷ 2)² × height. It gives the result in cubic feet, cubic yards, US gallons, and liters. A cylinder 4 ft across and 6 ft tall holds 75.40 cubic feet, which is 2.793 cubic yards or 564.0 gallons.

Use it for sonotube piers, round columns, drums, stock tanks, culvert sections, and well casings. Anything with straight sides and a round cross-section works.

The formula in plain words

Think of a cylinder as a stack of identical round coins. The area of one coin face is π × r². The number of coins is the height. Multiply the two and you have the volume.

1. Radius = diameter ÷ 2
2. End area = 3.14159 × radius × radius
3. Cubic feet = end area × height
4. Cubic yards = cubic feet ÷ 27
5. Gallons = cubic feet × 7.48052, and liters = gallons × 3.78541

Because the radius is squared, diameter matters far more than height. Doubling the height doubles the volume, but doubling the diameter quadruples it.

Worked examples

1. Water drum or tank: 4 ft diameter, 6 ft tall

• Radius: 4 ÷ 2 = 2 ft
• Cubic feet: 3.14159 × 2 × 2 × 6 = 75.40 ft³
• Cubic yards: 75.40 ÷ 27 = 2.793 yd³
• Gallons: 75.40 × 7.48052 = 564.0 gal
• Liters: 564.0 × 3.78541 = 2,135.0 L

2. Deck pier: 12-inch sonotube, 4 ft deep

• Diameter: 12 in = 1 ft, so the radius is 0.5 ft
• Cubic feet: 3.14159 × 0.5 × 0.5 × 4 = 3.14 ft³
• Cubic yards: 0.116 yd³

Eight of these piers need 8 × 3.14 = 25.1 ft³. That is about 42 of the 80-lb concrete bags at 0.6 ft³ each, before waste. The sonotube calculator handles counts and bags directly.

Cylinder volume reference

Diameter × height	Cubic feet	Cubic yards	Gallons
8 in × 4 ft	1.40	0.052	10.4
1 ft × 4 ft	3.14	0.116	23.5
1.5 ft × 3 ft	5.30	0.196	39.7
2 ft × 4 ft	12.57	0.465	94.0
4 ft × 6 ft	75.40	2.793	564.0
8 ft × 2 ft	100.53	3.723	752.0
6 ft × 10 ft	282.74	10.472	2,115.1
10 ft × 12 ft	942.48	34.907	7,050.2

Turning the volume into an order

• Concrete: order by the cubic yard for ready-mix, or divide cubic feet by 0.6 for 80-lb bags and by 0.45 for 60-lb bags.
• Water: use the gallons figure. Water weighs about 8.34 lb per gallon, so the 564-gallon drum in example 1 holds about 4,700 lb of water. Check that the base can carry it.
• Gravel or soil in a round planter: take the cubic yards and multiply by the material’s weight per yard.

How to measure a cylinder

• Diameter: measure straight across through the center at the widest point. If you can only reach around the outside, wrap a tape and divide by 3.1416. The circumference calculator explains how.
• Inside or outside: for capacity (water, grain, soil), use the inside diameter. For concrete forms, the inside of the tube is the pour.
• Height: measure along the straight side to the fill line. A tank that is 6 ft tall but overflows at 5.5 ft holds only the 5.5 ft volume.
• Odd ends: domed or rounded tank ends add volume. Add a hemisphere, or use the capsule volume calculator.

Common mistakes

• Using the diameter as the radius. That makes the answer four times too big. A 4 ft cylinder with radius entered as 4 shows 301.6 ft³ instead of 75.40.
• Mixing inches and feet. An 8-inch tube entered as 8 gives a volume 144 times too large. Convert to 0.667 ft first.
• Tapered shapes. Buckets, planters, and silo hoppers narrow toward one end. Use the cone volume calculator or the frustum version instead.

For tanks with a fill level, the tank volume calculator shows filled gallons. For boxes and other shapes, use the volume calculator.