What I do here
I built every tool and guide on this site, and I maintain them. That means writing the arithmetic each calculator runs, finding the paper or rule behind every formula, and rebuilding the page when a source changes. All the tools share one small calculation engine, so a pace on the marathon chart is the same to the second as the pace the calculator gives you, and the printed tables are produced by that same engine when the site is built.
The build is checked mechanically before anything is published: a set of tests compares the engine with hand-worked values (a 4-hour marathon is 9:09 per mile, lane 8 is 453.03 m per lap, a 2:00 rowing split is 202.5 W), every page is crawled for broken links, and every tool is loaded on a phone-sized screen to confirm it gives a result. That is a process, not a promise, and when a reader finds a mistake the page is fixed and its date updated.
What I am not
I am not a running coach, an exercise physiologist, a doctor or a dietitian, and nothing here should be read as if I were. So the site does not tell you how to train. It reports what a named source says, shows the arithmetic, and states plainly where a choice is ours rather than a source's. The clearest example is the repetition pace on the training pace calculator: the published bands stop at "over 100% of VO2 max", so we use your predicted mile race pace, and the page says so.
Where a value cannot be published honestly, it is not published. The steps per mile calculator has no height-based estimate because the common formula has no study behind it that I could find. The VO2 max, Rockport and Bruce pages give a score but no "excellent / good / poor" rating, because I found no open source for those tables; the Harvard step test shows one published study's bands only if you ask for them, labelled as that study's.
Where the numbers come from
Every formula is listed with its source on the methodology page: Riegel's 1981 endurance formula, the Daniels and Gilbert oxygen-cost equations, the ACSM metabolic equations, the 2024 Adult Compendium of Physical Activities, Minetti and colleagues' slope measurements, the World Athletics track and road rules, Concept2's published formulas and Alan Jones's 2025 road age-grading tables.
Elsewhere
I build free calculator websites and work in digital marketing. You can find me on LinkedIn. For corrections or questions about a page, use the contact page.