How to Use
Everything the two calculators can do, in five minutes.
Everything on both calculators follows the km / mi switch in the header, and the choice is remembered between visits.
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 50K), common paces, and finish times.
- Fine-tune any value with the +/− buttons under it: hours, minutes, and seconds for time, minutes and seconds for pace, and 0.1, 1, or 5 for distance.
- 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 empties the three fields; it does not change that setting. Switching the setting off clears what was already stored.
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.
1Say what the ground is like
Road, gravel, trail, technical, or rocky. This is the one thing an elevation profile cannot tell us, and it is worth a lot: the same profile on fire road and on boulders is half an hour apart. Rough ground counts far more on the descents than on the climbs, which is why it is asked separately from your pace.
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 a dialog opens asking how to split it, already set to Peak & Valley, so confirming is usually all it needs.
- 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 your flat road pace, what you could hold on level tarmac at race effort, or a target finish time, and the matching flat pace is found for you. Either one is enough. Give the road figure even for a mountain race: the ground setting adds the rough-terrain cost on top, so folding it in yourself would charge you twice.
4Fine-tune the segments
- Edit a segment’s name, distance, climb, and descent directly in the table.
- Muted paces are calculated for you; click one and type your own to lock that segment. When you are working to a target time, the rest of the plan re-solves around every locked segment so the target still holds. Clear the value to hand the segment back to the model.
- Each row has its own split and delete buttons, and a menu for inserting a segment after it or merging it with the one above or below. “+ Add segment” splits the last segment in half, so the total distance does not change.
- 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.
Your plan is still there next time
Segments, target and settings are kept in this browser, so closing the tab does not cost you the plan. Clear wipes it deliberately.
Want the math?
The About page shows how climbs, descents, and rough ground are each priced, with the formulas and their limits.