Solid rod & bar
Rod Volume
The material volume of a solid round rod or bar from its diameter and length — handy for weight and stock estimates.
This rod volume sizes solid round stock. Enter the bar's diameter and length for its volume, then add a metal density if you want an estimated weight.
The reason this shape earns a dedicated tool is that its two measurements are easy to get wrong. Confusing radius with diameter doubles your answer; mixing inches with centimetres throws it out completely. Keeping each measurement labelled, and letting the tool convert, removes both traps before they cost you.
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 20 cm (so a radius of 10 cm) and a height of 40 cm. The base area is π × 10² = 314.16 cm², and multiplying by the height gives a volume of about 12.57 litres (12,566 cm³ · 3.32 US gallons).
For anything that holds liquid, measure the inside of the cylinder — the wall takes up space that the contents cannot.
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.
What people work out next
To save you a second search, here are the related answers people most often want straight after this calculation:
How do I find a missing dimension?
If you know the volume you need and one measurement, the reverse-solver returns the height, radius or diameter that matches it.
Can I get the weight too?
Tick estimate weight, pick a material, and the calculator multiplies volume by density to show the mass in kilograms and pounds.
What will the volume be in gallons or litres?
You do not have to choose up front. The result lists litres, US gallons, Imperial gallons, cubic feet and more together, so you can switch the main unit whenever you like.
What if I have the diameter, not the radius?
Toggle the base input to diameter and the tool halves it for you. There is also a circumference option for when that is all you were able to measure.
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.
Reading and converting your result
Showing every unit at once is about speed and safety: you see the answer in litres, gallons and cubic feet side by side, so there is no chance of applying the wrong conversion factor. Change the output unit at the top to make any of them the headline figure, switch the precision to exact if you want the value in terms of pi, and use copy-result to paste a tidy summary wherever you need it.
What to work out next
Once you have your answer you may also want to work in mass & density hollow tube & pipe cylinder volume. These related calculators pick up where this one leaves off:
When this comes in handy
People reach for this in a range of situations:
- Estimating the weight of round bar stock
- Costing raw material for turned parts
- Comparing rod sizes by volume
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.
Frequently asked questions
How do I find the volume of a round rod?
V = π r² h, using the rod's radius and its length. Add a metal density to estimate the weight.How do I get the weight of a bar?
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.