CalcBuilder example
Running Pace & Race Predictor
September 21, 2026
Live result on the frontend
The Running Pace & Race Predictor takes a recent race result and answers two questions runners ask constantly: what pace was that, and what could I run at the other distances? It uses the Riegel formula and lays the answers out in a tidy table.
What it calculates
A visitor picks a reference distance and enters hours, minutes and seconds. The calculator returns:
- Pace — seconds per kilometre and per mile, formatted as minutes:seconds, plus the 400 m lap time.
- Speed — average speed in km/h and mph.
- Race predictions — predicted 5K, 10K, half marathon and marathon times with Riegel’s formula
T2 = T1 × (D2 / D1)^1.06, each with its pace, and the row for the reference race highlighted. - Pace zones — a six-part bar from easy running to speed repetitions, taking each zone’s pace from the predicted race paces.
How it’s built
A List field carries the distance in kilometres as the option value, and three Number fields take the finishing time. The PHP Code converts everything to seconds, applies the Riegel exponent to each target distance and formats the results with two small closures (h:mm:ss and m:ss).
The predictions table and the zone bar are HTML built in PHP loops and printed by the Exit Layout with ##pred_rows## and ##zone_html##. The reference row gets a CSS class so it stands out, and the same calculator works whichever distance is chosen.
The input form as your visitors see it, styled with the Form Layout.
Four fields: a List for the reference distance and three Number fields for hours, minutes and seconds.
The PHP Code: time to seconds, pace and speed, the Riegel loop, the zones and the HTML builders.
The Exit Layout: three hero cards, six metric cards, the predictions table and the pace-zone bar.
Want this exact example on your own site?
Download the file above, then in your Joomla admin open Components › CalcBuilder › Import and upload it — it's the same file you'd get from that component's own Export button, so it drops in as a ready-to-use, fully working copy in one step.
