Methodology

Each tool's How it works section explains its calculation, sources and limitations. The rules below describe the shared approach.

Shared rules

• 1 mile is exactly 1609.344 metres.
• A marathon is 42.195 km and a half marathon is 21.0975 km.
• Times show as h:mm:ss or m:ss, rounded half up to the nearest second. We keep full precision while calculating and round only what you see, so small rounding errors never add up.
• Your chosen goal time sets the finish time for the band.
• Distance-based tools offer a kilometres and miles switch.

Where the rules come from

Target times are calculated from your chosen distance, finish time and pacing strategy. Even pacing uses the same pace throughout; a negative split uses a faster pace for the second half. The pace band page explains the calculations and shows a worked example.

Training plans and estimates

Training plans use the site's stated progression, cutback and taper rules. Dated plans start on a Monday and stop at race day or their final session. These rules are planning models, not personalised prescriptions. The finish time predictor uses a distance-based endurance estimate; heart-rate charts use an age formula or your entered maximum. Neither can assess your individual fitness or suitable exercise intensity.

Running log totals

Runs are stored in metres and grouped into Monday-to-Sunday weeks. Average pace is total time divided by total distance, rather than the average of individual run paces. Display rounding does not change saved distances or the numeric precision in CSV downloads. Small positive distances retain additional digits when ordinary rounding would display zero.

Sources

Facts come from official sources: government bodies, regulators, recognised professional bodies or the governing body of the sport. Each tool page lists its sources with the date we last checked them.

Testing

Every tool is tested against a worked example before it goes live, and the example is shown on the tool page so you can check it yourself.

No expert review

No coach, doctor or other professional has checked our pages. Please use your own judgement and speak to a qualified professional before you act on a result.