About PaceLab
Free running calculators with maths you can check, and no strings attached.
PaceLab is a free running pace calculator and reference site at paceslab.com, published and maintained by the Dutch studio FusionStudios. It publishes 9 pace charts, 10 marathon goal-time pages and five calculators. Everything runs in your browser, there is no account, and every formula and constant it uses is written out on the methodology page.
What this site is
A small collection of running tools that each do one job: a pace calculator, a finish time calculator, a race time predictor, a splits calculator and a treadmill converter, alongside pace charts from one mile to 50 kilometres and marathon goal pages with full split tables.
Who publishes it
PaceLab is built and maintained by FusionStudios, a web studio in the Netherlands. There is no invented running coach behind these pages and no fabricated credential, because the site does not need one: the value here is that the arithmetic is published rather than asserted. Every constant, every formula and every source is on the methodology page, so you can check any number on the site by hand rather than take our word for it.
Where the site touches on anything that would need expertise rather than arithmetic, it says so and stops. It does not publish heart-rate zones, training plans or medical advice, and the methodology page explains why.
The principles
Every calculation runs client-side in your browser, so your training data never leaves the tab. There is no backend to send it to. There are no accounts, no paywalls, no exit-intent popups and no email wall in front of anything. See the privacy policy for the details.
When a formula or a table changes, it goes in the changelog with a date. When a page is reviewed, that date is printed at the bottom of it. Both are there so you can tell how old a number is.
Use it elsewhere
The pace dataset is a free CSV and JSON download under CC BY 4.0, and the embed page has copy-paste code for putting the calculator on a club or race site. Both are free, including commercially.
Something looks wrong
Then it is worth an email. Send the page, the input and the number you expected via contact, and it gets checked against the generator.
Last reviewed . Formulas, constants and sources: methodology. Changes to any calculation are logged in the changelog.