Cylinder Volume Calculator

Calculate cylinder volume in cubic feet, gallons, and liters, plus surface area.

By Konstantin Iakovlev · Updated September 2026 · Source: Khan Academy

Volume

141.37 cu ft

Surface Area

150.80 sq ft

Volume Conversions

Cubic Feet141.37
US Gallons1,057.53
Liters4,003.19
Surface Area150.80 sq ft

Use the Cylinder Volume Calculator above to calculate your results. Enter your values and see instant results — all calculations run in your browser.

Disclaimer: This calculator is for informational purposes only. Results are estimates based on the information you provide and the assumptions described on this page.

How It Works

Feed in a radius and a height, and you get back the volume of a cylinder in cubic feet, gallons, and liters, plus its total surface area. Those numbers matter in practical settings, from sizing a grain silo or water tank to specifying an industrial fluid container.

Volume comes from the standard expression V = πr²h, with 'r' the radius and 'h' the height. Surface area uses A = 2πrh + 2πr², which adds the curved lateral wall to the two circular end caps. The tool applies these formulas at full precision so the geometry holds up even at large scales.

Enter both the radius and the height in feet: the results are labeled cubic feet and square feet, and the gallon and liter figures are converted from cubic feet. Entering both in inches inflates the volume by a factor of 1,728 (12³); a radius in inches with a height in feet inflates it 144 times, and a height in inches alone 12 times. One more thing worth weighing: on thick-walled cylinders the inside and outside dimensions diverge, so measure to the surface that bounds the volume you actually care about.

Example: Capacity of a Fuel Storage Tank

  1. 1 A vertical fuel storage tank has an internal diameter of 12 feet and a height of 20 feet. How much does it hold in gallons?
  2. 2 The calculator takes the radius, so halve the diameter: r = 12 ft / 2 = 6 ft. Enter radius 6 and height 20. Volume V = π × 6² × 20 = π × 720 = 2,261.95 cubic feet.
  3. 3 Gallons: 2,261.95 × 7.48052 = 16,920.54 US gallons. Liters: 2,261.95 × 28.3168 = 64,051.09 liters. Surface area: 2π × 6 × 20 + 2π × 6² = 753.98 + 226.19 = 980.18 square feet.
  4. 4 Because the inputs are internal dimensions, 16,920.54 gallons is the tank's brim-full capacity. For the outside surface area (paint or insulation), run it again with the outside radius and height.

Source: Khan Academy · Last updated: September 2026

Frequently Asked Questions

How many gallons does a cylinder hold based on its dimensions?
Volume equals pi times radius squared times height (V = πr²h). For a cylinder with 3-foot radius and 5-foot height, volume is π x 9 x 5 = 141.37 cubic feet, or about 1,057.53 US gallons (141.37 x 7.48052).
How many gallons does a cylindrical tank hold?
Calculate the volume in cubic feet (πr²h), then multiply by 7.48 to convert to US gallons. A 2-foot radius, 4-foot tall tank holds about 50.27 cubic feet or 376 gallons.
How do you find the surface area of a cylinder?
Total surface area equals 2πr² + 2πrh (two circles plus the side). For radius 3 and height 5, that is 2π(9) + 2π(15) = 56.55 + 94.25 = 150.80 square units.

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