Engine capacity calculator
Type the bore, the stroke and the number of cylinders. You get the engine size in cc, litres and cubic inches, the way a bike’s spec sheet gives it.
499 cc
That is 0.50 litres, or 30 cubic inches: 2 cylinders of 249.6 cc each. The bore is 67.00 mm and the stroke 70.80 mm.
Plain geometry: each cylinder is π ÷ 4 × bore² × stroke. 1 inch = 25.4 mm, from the Weights and Measures Act 1985, read on 30 October 2026.
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How to use it
The bore is the width of each cylinder and the stroke is how far the piston travels. Both are on most spec sheets, often written as bore × stroke, in millimetres. Type them in, pick millimetres or inches, and add the number of cylinders. The answer updates as you type. It is handy when you are looking at a big-bore kit, or checking an old bike's numbers against its paperwork.
How it is worked out
Each cylinder sweeps out a shape like a tin can. Its volume is π ÷ 4 × bore² × stroke. Multiply by the number of cylinders for the whole engine. With the sizes in millimetres, divide by 1,000 to get cubic centimetres (cc).
| Step | Example: 67 × 70.8 mm, twin |
|---|---|
| One cylinder | 0.7854 × 67² × 70.8 ÷ 1,000 = 249.6 cc |
| Two cylinders | 249.6 × 2 = 499.2 cc |
| In litres | 499.2 ÷ 1,000 = 0.50 litres |
For inches, the tool turns them into millimetres first: 1 inch is 25.4 mm, from the Weights and Measures Act 1985. A cubic inch is 16.387 cc.
Why the badge can differ
The size on the side panel is a name, and it can be rounded. The true swept volume is what this sum gives. If a figure matters, say for an insurance form, go by the bike's paperwork rather than this sum. Curious about what cc means in the first place? Our guide to what cc means on a motorbike starts from scratch.
Written by Craig Fearn, Throttlefolio. Last updated .
Questions answered
How do I work out engine cc from bore and stroke?
π ÷ 4 × bore² × stroke, in millimetres, ÷ 1,000 gives cc for one cylinder. Multiply by the number of cylinders.
What is 499 cc in litres?
0.499 litres. Divide cc by 1,000 for litres.
How many cc is a cubic inch?
16.387 cc, because an inch is 25.4 mm.
Keep reading
- What does cc mean on a motorbike?
Cc stands for cubic centimetres. It's the unit used for an engine's displacement, meaning the volume its pistons sweep, and it's the figure UK vehicle…