Calculate drum capacity, radius, or height from the other two values using cylinder volume formulas with metric, inch, foot, liter, and gallon 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:
V = \pi r^2 h
If you know the drum volume and height, the radius is calculated with:
r = \sqrt{\frac{V}{\pi h}}If you know the drum volume and radius, the height is calculated with:
h = \frac{V}{\pi r^2}- V = drum capacity or volume
- r = inside radius of the drum
- h = inside height of the drum
- π = pi, approximately 3.14159
The calculator lets you enter any two values and solves for the missing one. If you enter radius and height, it calculates drum volume. If you enter height and volume, it calculates radius. If you enter radius and volume, it calculates height.
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 cm³ | 0.001 m³ |
| 1 US gallon | 3.785411784 L | 0.003785411784 m³ |
| 1 cubic foot | 28.316846592 L | 0.028316846592 m³ |
| 1 cubic inch | 0.016387064 L | 0.000016387064 m³ |
Approximate Cylindrical Drum Capacities
| Inside diameter | Inside height | Approximate volume |
|---|---|---|
| 20 in | 30 in | 40.8 US gal |
| 22.5 in | 33.5 in | 57.5 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.
V = \pi r^2 h
V = \pi(0.30)^2(0.90)
V = 0.25447\text{ m}^3 = 254.47\text{ L}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.
h = \frac{V}{\pi r^2}h = \frac{0.200}{\pi(0.25)^2}h = 1.0186\text{ m} = 101.86\text{ cm}The required inside height is about 101.86 cm.
FAQ
Should I use radius or diameter for drum capacity?
Use radius in the calculator. Radius is half of the diameter. If you measured the drum diameter, divide it by 2 before entering the value. For example, a 60 cm diameter drum has a 30 cm radius.
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.
