Changelog
What changed in the maths, and when. Cosmetic changes are not listed here.
There are 7 logged changes, the most recent on 2026-08-05. This page records changes to formulas, constants, tables and tools only. If a number you relied on moved, it moved for a reason that is written down here, and the reasoning behind the formulas themselves is on the methodology page.
Methodology page, sources and error margins published
Every constant and formula the site uses now has one page that states it, with full citations for Riegel (1981) and Jones and Doust (1996) and an explicit section on where each model stops being reliable. The site also states what it deliberately does not calculate, including heart-rate zones, and why.
Marathon goal-time pages added
Ten curated marathon goals from 2:45 to 5:30 now have their own page with a full 43-row kilometre split table, a 27-row mile split table, checkpoint times at every marker, a fade table and Riegel equivalents at five shorter distances. All figures are generated from the goal time and the exact distance of 42.195 km.
50K pace chart added, without a prediction
The 50K chart covers 3:00 to 8:00 as pure arithmetic. No predicted 50K time is offered from a shorter race, because Riegel's formula was fitted to endurance racing rather than to ultras and the reasons it fails past the marathon are not in the exponent.
Split tables now include the final partial segment
The goal-time split tables run to 42.195 km rather than to a round 42 km, so the last elapsed time lands exactly on the goal instead of 195 metres short of it.
Sitemap split by page type, lastmod taken from git
One sitemap per page type under a single index, and the lastmod on every URL is now the date of the last commit that changed that page rather than the build date. A lastmod that moves on every deploy carries no information.
Marathon pace chart and treadmill converter deepened
The marathon chart gained a one-minute-step table across the full 2:30 to 6:00 range and an equivalent-times table. The treadmill converter gained reference tables from 3.0 to 13.0 mph and 4.0 to 22.0 kph.
PaceLab published
Initial set of calculators, pace charts and guides, all client-side, with Riegel's formula cited on the race time predictor and Jones and Doust cited on the treadmill converter.
Reporting something that looks wrong
If a figure on this site disagrees with your own arithmetic, that is worth an email. The formulas are all published on the methodology page, so any value here can be checked by hand. Send the page, the input and the number you expected via contact.
Last reviewed . Formulas, constants and sources: methodology. Changes to any calculation are logged in the changelog.