Cylinder Capacity Calculator
How much does that tank, drum, or pipe actually hold? Guessing from the outside dimensions is how orders come up short and fills overflow, and the fix is one formula: measure the inside radius and height, and the volume follows.
This calculator runs that formula three ways: Volume mode gives capacity in cubic units, liters, milliliters, US and UK gallons, and US fluid ounces, with surface and base areas alongside; Hollow pipe mode separates a tube wall from the channel inside it; and Find a dimension mode works backward from a known volume to a missing height, radius, or diameter.
How it was calculated
Capacity here means a full, upright cylinder measured inside the walls. A tank filled partway, tilted, or fitted with dished ends holds a different amount, and the notes below explain how to handle those cases honestly.
Quick Answer
Key takeaways
- Capacity is base area times height: V = π × r² × h. The radius is squared, so doubling it quadruples capacity while doubling the height only doubles it.
- Measure inside the walls for a holding capacity. Outside measurements describe what the tank displaces, not what fits inside it.
- US and UK gallons differ by about 20 percent, and this tool reports both so a supplier quote cannot quietly switch between them.
- Hollow pipe mode keeps wall material volume and inner channel capacity separate. Confusing the two is the classic pipe ordering error.
- Find a dimension mode runs the formula backward in centimeters: the known radius or height goes in as cm, whatever unit the known volume uses.
- Quick Answer
- How to use the cylinder capacity calculator
- The capacity formula, mode by mode
- Worked example: from a lab cylinder to a water tank
- Hollow pipe mode: what the channel holds versus what the wall is made of
- Find a dimension: running the formula backward
- Measuring so the capacity is real, not nominal
- What competing cylinder tools miss
- Frequently Asked Questions
- Add This Calculator to Your Website
- References
How to use the cylinder capacity calculator
Start on the Volume tab. If you measured from the center of the end circle to the wall, leave the selector on Radius; if you measured straight across, switch it to Diameter and the tool halves the figure for you. Enter the height, or the length if the cylinder lies on its side, pick the one unit that matches both measurements, and press Calculate. The result leads with the volume in your cubic unit, then lists every conversion plus total surface area, lateral area, and base area for coating, wrapping, and footprint questions.
Use the Hollow pipe tab for any tube, and the Find a dimension tab when the volume is the known quantity, for example a label that says a vessel holds 50 liters alongside a tape measure that gives you its radius. For a rectangular tank or room rather than a round one, the cubic footage calculator covers box volumes with the same style of conversions.
Measure inside. Diameter across the inner walls, or radius from center to inner wall, plus the inner height or length.
Halve a diameter. The formula needs the radius; the Diameter option does this for you, r = d ÷ 2.
Square, multiply, convert. Volume = π × r² × h, then read the liter and gallon conversions in the same table.
The capacity formula, mode by mode
Every mode is the same geometry rearranged. The base of a cylinder is a circle with area π × r², and the volume is that area carried through the height, which is why the radius, not the height, carries the square.
The conversions are fixed definitions. A liter is exactly 1,000 cubic centimeters, as the NIST guide to SI volume units sets out, and a US gallon is exactly 231 cubic inches. The tool converts through cubic centimeters using 16.387064 cm³ per cubic inch and 28,316.846592 cm³ per cubic foot, then reports US gallons at 0.264172 per liter and UK gallons at 0.219969 per liter. Because the UK gallon is larger, its figure for the same tank is always the smaller number, a useful sanity check.
Worked example: from a lab cylinder to a water tank
The pre-filled case is a small cylinder, radius 5 cm and height 10 cm. Base area = π × 5² = 78.54 cm², and volume = 78.54 × 10 = 785.40 cm³. Every other figure in the result table is that one volume restated:
| Result | Value | How it comes from 785.40 cm³ |
|---|---|---|
| Liters | 0.79 L | 785.40 ÷ 1,000 |
| Milliliters | 785.4 mL | 1 cm³ is 1 mL by definition |
| US gallons | 0.21 gal | 0.7854 L × 0.264172 |
| UK gallons | 0.17 gal | 0.7854 L × 0.219969 |
| US fluid ounces | 26.6 fl oz | 785.40 ÷ 29.5735296 |
| Total surface area | 471.24 cm² | 314.16 lateral + 2 × 78.54 ends |
The same steps size a real tank. A water tank with a 40 inch diameter and a 60 inch height has a radius of 20 inches, so V = π × 20² × 60 = 75,398.22 in³, which the tool converts to 1,235.56 liters, 326.40 US gallons, or 271.78 UK gallons. The quick check agrees: 75,398.22 ÷ 231 = 326.40. For the capsule shape used by many pressure vessels, the capsule volume calculator adds the two hemispherical ends a plain cylinder leaves out.
Hollow pipe mode: what the channel holds versus what the wall is made of
A pipe is two cylinders sharing one length, and the two volumes answer different questions. The inner cylinder is the channel: it decides flow and how much liquid a run of pipe holds. The ring between the two cylinders is the wall: it decides how much metal, plastic, or concrete you are buying and, once multiplied by a density, what the pipe weighs.
The pre-filled pipe has a 10 cm outer diameter, an 8 cm inner diameter, and a 100 cm length. Outer radius 5 cm, inner radius 4 cm: the wall material is π × (5² − 4²) × 100 = 2,827.43 cm³, the inner channel is π × 4² × 100 = 5,026.55 cm³ or 5.03 liters (1.33 US gallons), and the wall thickness is (10 − 8) ÷ 2 = 1.00 cm. The channel holding more than the wall contains is normal for thin-walled tube, and exactly why outer dimensions alone overstate capacity.
This mode answers the capacity side of a pipe. When the job is the wall itself, its material volume broken out with weight in a chosen material, the dedicated cylindrical shell calculator goes deeper on that side. Capacity work starts from what fits inside; shell work starts from what the wall is made of.
Find a dimension: running the formula backward
Sometimes the volume is printed on the vessel and a dimension is what is missing. A jar labeled 785.4 cm³ with a measured radius of 5 cm must be 785.4 ÷ (π × 5²) = 10.00 cm tall, and the reverse mode returns that height as 10.00 cm, 0.10 m, 3.94 in, and 0.33 ft. Switch the finder to Radius or Diameter and it solves r = √(V ÷ (π × h)) instead, doubling the result for a diameter.
Two rules keep this mode honest. The known volume can arrive in cubic centimeters, cubic meters, cubic inches, cubic feet, liters, or US gallons, and the tool converts it to cubic centimeters before solving. The companion dimension is always entered in centimeters: the radius when finding height, the height when finding radius or diameter. Results come back in centimeters first, with inch, foot, and meter readings alongside. For a rectangular vessel, the same backward question belongs with the box volume calculator family of shapes rather than this round one.
Measuring so the capacity is real, not nominal
The formula is exact; the measurements are where capacity goes wrong. Measure the inside: a tank with a 40 inch outside diameter may offer only 38 inches of usable width, and because the radius is squared, that 5 percent width error becomes a 10 percent capacity error. Measure height to the fill line you will actually use, not the brim: fuel and propane vessels are routinely filled to about 80 percent of water capacity to leave expansion room. And keep both measurements in one unit, since mixing inches and feet distorts the volume by the cube of the conversion factor.
What competing cylinder tools miss
The top ranking cylinder capacity pages reviewed for this rewrite are strong on the forward formula and thin everywhere else. The gallons-focused tools add fill-depth tables for horizontal tanks but stop at volume in a few units, the deepest guide still tells pipe users to subtract an inner cylinder by hand, and the unit-rich rival that matches this tool on UK gallons offers no reverse solving at all.
Miss 1: no reverse solver. Real questions often start from a known volume: how tall must a 50 liter tank with this footprint be? Forward-only tools answer only by trial and error; Find a dimension mode solves height, radius, or diameter directly.
Miss 2: hollow cylinders done by hand. Pipe capacity is a subtraction problem, outer cylinder minus inner cylinder, and most tools leave both halves to you. Here the wall volume, inner capacity, and wall thickness arrive in one run.
Miss 3: one gallon, silently. Pages that report gallons without saying which kind invite a 20 percent ordering error. This tool prints US and UK gallons side by side, with milliliters and US fluid ounces in the same table.
One honest limit in the other direction: a leading rival handles horizontal tanks at partial fill depths, and this tool does not. If your tank lies on its side and is rarely full, that segment calculation matters more than anything here.
Frequently Asked Questions
Yes. Capacity is the volume stated as what the cylinder can hold, usually in liters or gallons, while volume is the geometric quantity itself. Both use V = π × r² × h, so a cylinder with a volume of 785.40 cm³ has a capacity of 0.79 liters.
Measure the inside for holding capacity. Outside measurements include the wall thickness, so they describe the space the tank itself occupies and overstate what fits in it. Because the radius is squared in the formula, even a small wall thickness inflates the result noticeably on narrow vessels.
A US gallon is exactly 231 cubic inches, or 3.785 liters, while a UK imperial gallon is 4.546 liters, about 20 percent larger. The same 1,235.56 liter tank is therefore 326.40 US gallons but only 271.78 UK gallons, so check which gallon a supplier means before ordering.
Use the Hollow pipe tab with the outer diameter, inner diameter, and length. The tool reports the wall material volume separately from the inner channel capacity in cubic units, liters, and US gallons, plus the wall thickness, so you can size both the fluid the pipe carries and the material it is made from.
Yes. The Find a dimension tab takes a known volume in cubic units, liters, or US gallons and solves for the missing height, radius, or diameter. The companion dimension you enter alongside it is always in centimeters: the radius when finding height, and the height when finding radius or diameter.
No. Every mode assumes an upright cylinder filled to the height you enter. A horizontal tank filled partway needs the circular segment area at the liquid surface, which this tool does not compute. For an upright tank, entering the actual liquid depth as the height gives the correct filled volume.
Yes. Enter both measurements in the single unit you select, whether centimeters, meters, inches, feet, or millimeters. If one measurement is in inches and the other in feet, convert one of them first, because mixing units distorts the volume by the cube of the conversion factor.
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References
- National Institute of Standards and Technology, “SI Units: Volume” – the liter as a cubic decimeter, the milliliter as a cubic centimeter, and the 1,000 L per cubic meter ladder used for every metric conversion here. NIST: SI Units, Volume. Accessed October 2026.
- Wikipedia, “Gallon” – the US gallon defined as exactly 231 cubic inches (3.785411784 L) and the imperial gallon as 4.54609 L, the basis for reporting both gallons side by side. Wikipedia: Gallon. Accessed October 2026.
- CK-12 Foundation, “Volume of a Cylinder” – the V = π r² h formula, the base area form V = B h, and the tube formula V = π h (R² − r²) behind hollow mode. CK-12: Volume of a Cylinder. Accessed October 2026.
- LibreTexts, “SI Length and Volume Units” – the liter as a 10 cm cube (1,000 cm³) and the milliliter as one cubic centimeter, confirming the metric conversions. LibreTexts: SI Length and Volume Units. Accessed October 2026.
- US Code of Federal Regulations, 7 CFR 160.92, “Meaning of the word gallon” – the regulatory definition of the US standard gallon as 231 cubic inches. 7 CFR 160.92: Meaning of Gallon. Accessed October 2026.
- Citizendium, “U.S. Customary Units” – unit tables confirming one US gallon as exactly 231 cubic inches and the imperial gallon as roughly 20 percent larger. Citizendium: U.S. Customary Units, Volume. Accessed October 2026.