How to Use

Everything the two calculators can do, in five minutes.

Basic Calculator

The Basic calculator solves the classic running equation — distance, time, pace. Give any two and the third is calculated instantly; there is no Calculate button.

  • Type values directly, or use the presets: race distances (5K to 100K), common paces, and finish times.
  • Fine-tune any value with the +/− nudge buttons (seconds, minutes, hours).
  • The two fields you touched most recently count as the inputs — edit a different pair to solve for another field.
  • Splits: per-kilometer (or per-mile) passing times; switch the interval with the 1 / 5 / 10 tabs.
  • Pace scenarios show how small pace changes move your finish time; Training zones derive easy-to-interval paces from your result.
  • “Remember values” keeps your inputs in this browser between visits; Clear wipes everything.

Open Basic →

Advanced Calculator

The Advanced calculator plans a race segment by segment. Each segment has its own distance, climb, and descent — and gets its own pace, so the plan follows the actual course instead of a flat average.

1Choose a surface

Road treats the course as flat-equivalent road running. Trail enables elevation-aware pacing: pick a pace algorithm (Naismith, Tobler, or Minetti) and a terrain factor (1.0 = smooth trail … 1.3 = off-trail) for technical ground.

2Load a route — or set a distance

Click “Load GPX / KML / KMZ” and pick an exported route file (GPX, KML, KMZ, or Suunto JSON). The route appears on the map with its elevation profile and is automatically split into segments at peaks and valleys.

  • The Segmentation button reopens the auto-split dialog: every N km, Peak & Valley (with a prominence threshold), or one manual segment.
  • Drag the vertical boundaries on the elevation chart to move segment borders.
  • No file? Type a total distance or tap a race preset, and build segments by hand.
  • Changing the distance after loading a route scales all segments proportionally.

3Set your target

Enter a target flat pace — the pace you could hold on flat ground at race effort — or a target finish time, and the matching flat pace is found automatically. Either one is enough.

4Fine-tune the segments

  • Edit a segment’s name, distance, climb, and descent directly in the table.
  • Muted paces are calculated automatically; click one to type a manual override, clear it to return to auto.
  • The row menu inserts, splits, merges, or deletes segments; “+ Add segment” splits the last one in half.
  • Drag rows to reorder segments.

5Read the results

Below the table you get total time and average pace, split times (1 / 5 / 10 tabs), pace scenarios, and training zones. Export the full plan as CSV, or press Clear (top right, or under the table) to start over.

Open Advanced →

Your data stays with you

Everything runs in your browser. Route files are parsed locally and never uploaded; your values are stored only in this browser.

Want the math?

The About page explains the three pace algorithms, their formulas, and when to trust each one.

Read about the algorithms →