Mass & density
Density of a Cylinder Calculator
Volume is only half the story — add a material density to estimate the weight of a solid or filled cylinder in kg and pounds.
Dimensions give you volume; weight needs one more thing — the density of whatever the cylinder is made of or filled with. This density of a cylinder calculator multiplies volume by density (mass = ρ V) to estimate weight in kilograms and pounds.
Weight is where volume meets the real world. A tank's size tells you nothing about the load it puts on a floor until you bring in what is inside it, and the same round bar is feather-light in aluminium and heavy in steel. Density is the bridge between the two.
The formula behind it
The volume of a cylinder is:
V = π r² hA worked example
Worked example. Take a cylinder with a diameter of 15 cm (so a radius of 7.5 cm) and a height of 30 cm. The base area is π × 7.5² = 176.71 cm², and multiplying by the height gives a volume of about 5.30 litres (5,301 cm³ · 1.40 US gallons).
Weight depends entirely on the material's density, which the tool needs as an input. Densities also vary with temperature and grade, so treat the mass as an estimate.
Conversions use standard factors: 1 US gallon = 231 in³, 1 Imperial gallon = 4.54609 L, 1 litre = 1000 cm³.
Using the calculator
- Measure across the circular end — the diameter or radius.
- If you measured the diameter, halve it to get the radius r.
- Square the radius and multiply by π to get the base area.
- Multiply the base area by the height h: V = π r² h.
- Convert the result into your preferred unit above.
Getting an accurate measurement
If you can only reach the top, measure the diameter across the opening and halve it. Keep every measurement in the same system, and let the tool convert between units for you.
After you have your answer
The figure above is usually the start, not the finish. These are the questions that tend to come next, answered here so you do not have to run another search:
What density should I use?
Pick a preset — water, steel, aluminium, concrete and more — or type a custom value. Density is what turns a volume into a weight, so the result depends directly on it.
What is the weight in pounds and kilograms?
Both are shown. The tool reports mass in kilograms, pounds and grams once you supply a density, so you can use whichever your job needs.
Does temperature matter?
For liquids, slightly — density drifts a little with temperature. The presets use typical room-temperature values, which are close enough for almost all estimates.
What to watch out for
The commonest slip is using the diameter where the formula wants the radius, which on its own quadruples the base area. Close behind is mixing units, such as a radius in centimetres with a height in metres. Keep every length in the same unit, or let the tool convert, and double-check whether you measured to the centre or across the whole width. When a figure looks surprising, that width measurement is almost always where the problem is hiding, so re-read it first.
One result, every unit
Because volume units are where most errors creep in, the tool does the converting for you. Enter your measurements once and every common unit appears together, from millilitres up to cubic metres and across to US and Imperial gallons. Pick whichever the task calls for and lift the rest from the list; nothing needs a second calculation. The result also updates live as you change a measurement, so you can compare two sizes quickly without starting over.
What to work out next
Once you have your answer you may also want to work in cylinder volume solid rod & bar volume formula. These related calculators pick up where this one leaves off:
When this comes in handy
It comes in handy across quite different tasks:
- Estimating the shipping weight of round stock
- Sizing supports for a filled tank
- Comparing materials by weight for a part
To sum up, the whole job is two measurements and one formula. Enter them above, pick your unit, and you have an accurate figure plus every equivalent unit beside it. Keep a copy with the copy-result button, save the shareable link if someone else needs the same numbers, and use the history panel to compare a few options without starting from scratch.
Questions people ask
What is the formula for the volume of a cylinder?
V = π r² h — the area of the circular base (π r²) multiplied by the height (h). If you have the diameter instead of the radius, halve it first: r = d ÷ 2.Do I use radius or diameter?
What units can I use?
Is the volume of a cylinder squared or cubed?
Does this work for a tank or a pipe?
How do I calculate the mass of a cylinder?
mass = ρ × V. Water is about 997 kg/m³; steel is about 7850 kg/m³. Pick a material or enter a custom density above.