Calculate cylindrical drum capacity from inside diameter and height, or solve for diameter or height, with liters, gallons, cubic feet, and metric units.
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Drum Capacity Formula
The drum is treated as a right circular cylinder. The main formula for drum capacity, or cylindrical volume, is:
If you know the drum volume and height, the radius is calculated with:
If you know the drum volume and radius, the height is calculated with:
- V = drum capacity or volume
- r = inside radius of the drum
- h = inside height of the drum
- ฯ = pi, approximately 3.14159
Select the quantity to find, then enter the two known values. The calculator uses inside diameter, not radius: diameter and height give capacity; height and capacity give diameter; diameter and capacity give height. The formulas above use radius, which equals half the diameter.
All length values are converted to meters before calculation, and all volume values are converted to cubic meters. The result is then converted back to the unit you selected.
Common Drum Volume Unit Conversions
| Unit | Equivalent | In cubic meters |
|---|---|---|
| 1 liter | 1,000 cmยณ | 0.001 mยณ |
| 1 US gallon | 3.785411784 L | 0.003785411784 mยณ |
| 1 cubic foot | 28.316846592 L | 0.028316846592 mยณ |
| 1 cubic inch | 0.016387064 L | 0.000016387064 mยณ |
Approximate Cylindrical Drum Capacities
| Inside diameter | Inside height | Approximate volume |
|---|---|---|
| 20 in | 30 in | 40.8 US gal |
| 22.5 in | 33.5 in | 57.7 US gal |
| 30 cm | 50 cm | 35.3 L |
| 60 cm | 90 cm | 254.5 L |
Example Calculations
Example 1: Find drum volume from radius and height
Suppose a drum has an inside radius of 30 cm and an inside height of 90 cm.
The drum capacity is about 254.47 liters.
Example 2: Find height from volume and radius
Suppose a drum volume is 200 L and the inside radius is 25 cm.
The required inside height is about 101.86 cm.
FAQ
Should I use radius or diameter for drum capacity?
Enter inside diameter in the calculator. Radius is half of diameter and is used in the formulas above. If you measured a 30 cm radius, enter a 60 cm diameter. The radius-based examples above therefore use diameters of 60 cm and 50 cm.
Does this calculate total capacity or usable capacity?
This calculates the geometric volume of a cylindrical drum based on the inside radius and inside height. Actual usable capacity can be lower if the drum has thick walls, rounded ends, internal parts, a lid shape, or required empty space at the top.
Why are inside measurements important?
Capacity depends on the space inside the drum, not the outside dimensions. If you use outside radius or outside height, the result may overstate the actual volume, especially for thick-walled containers.
