Formula & reference
Behind every calculator is a bit of geometry and a few conventions worth understanding. This reference set explains the displacement formula, how to measure bore and stroke, what 'engine size' actually means, how displacement drives vehicle tax in some countries, and where to find every tool on the site. Read these to understand why the numbers come out as they do. The material is deliberately layered — the formula and engine-size pages cover the fundamentals from plain definitions, the how-to-measure guide gets practical with bore gauges and crank throws, and the displacement-tax page shows where engine size still shapes what you pay and where policy has moved to emissions or power instead. Each reference links to the tool that puts its ideas to work, so the reading and the calculating reinforce each other.
The Engine Displacement Formula, Explained
The engine displacement formula with variable definitions, why bore is squared, and worked metric and imperial examples — plus a live calculator.
Open tool →How to Measure Engine Displacement
Step-by-step guide to measuring bore and stroke, choosing published specs vs measured bore, and turning them into an accurate displacement figure.
Open tool →Engine Size, Capacity & Displacement — What They Mean
Engine size, capacity, volume and displacement explained, with the difference between total swept volume, per-cylinder volume and chamber volume.
Open tool →Engine Displacement Tax by Country
See which displacement tax band you land in for Japan, China, Germany and Singapore, and where CO₂ or power replaced it.
Open tool →Engine Displacement Guides & Reference
In-depth guides on engine displacement, bore and stroke, stroker kits, compression and unit conversion, with reference charts for common builds.
Open tool →Every Engine Displacement Calculator on This Site
A directory of all engine displacement calculators and converters here — by unit, by engine type and by task — so you can jump straight to the right tool.
Open tool →Looking for something else? The full calculators directory lists every tool, or start from the main displacement calculator.