Jars, cans & cups
Cup Volume Formula
Everyday round containers — jars, cans, cups and moulds. Enter the inside dimensions for a capacity in millilitres or cups.
This cup volume formula turns a round container's inside diameter and height into a capacity you can use in the kitchen or pantry, in millilitres and cups.
Round containers — jars, cans, cups, tins and moulds — are just short, wide cylinders, and the questions are practical: will this hold the batch, and how does it compare with the tin the recipe assumed? Measuring the inside, and reading millilitres or cups, answers both.
How to work it out
- 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.
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).
Measure the inside of the container, not the outside — and remember most jars and cans are filled to just below the rim, so usable capacity is a touch less.
Conversions use standard factors: 1 US gallon = 231 in³, 1 Imperial gallon = 4.54609 L, 1 litre = 1000 cm³.
After you have your answer
Most jobs need one or two more things once the volume lands. The common follow-ups, with the numbers you need, are below:
What if the container is tapered rather than straight?
This assumes straight sides. For a gently tapered tin the straight-side figure is a close estimate; for a strong taper, measure at the average width for a better result.
How many cups or fluid ounces is that?
The millilitre result is shown next to cups and US fluid ounces, so a jar or tin capacity drops straight into a recipe.
How do I compare two tins?
Work out the volume of each tin and keep the batter depth similar. If the new tin holds less, reduce the mix or expect a taller bake.
Should I measure inside or outside?
Inside — the wall holds nothing. Most containers are also filled to just below the rim, so usable capacity is a touch less than the geometric figure.
Where people use this
People reach for this in a range of situations:
- Swapping between two baking-tin sizes
- Measuring a jar's true capacity
- Portioning storage containers
Getting it right
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
One number, many units. Whatever you enter, the result lists the same volume as litres, US gallons, Imperial gallons, millilitres, cubic centimetres, cubic inches, cubic feet, cubic yards and cubic metres at the same time. You almost never have to convert by hand: read the figure in the unit your job uses and copy any of the others straight from the breakdown. If you need a shareable version, the copy-link button preserves your exact inputs so a colleague opens the page with the same calculation already filled in.
Keep going
Once you have your answer you may also want to work in litres & liters cylinder volume gallons. These related calculators pick up where this one leaves off:
The bottom line: with the radius or diameter and the height, the volume follows immediately, and the breakdown lets you hand the same number to anyone in the unit they prefer. Measure inside dimensions for anything that holds liquid, leave a little headspace at the top of a real container, and treat the geometric figure as a clean maximum rather than the final word on usable capacity.
Frequently asked questions
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 find the volume of a jar or can?
How do I swap between two round baking tins?
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.