Put in the distance and the time you want. Then decide how to run it: even, out conservative and home fast, or a kick over the last miles. Mark the hills and the splits adjust so the finish time still holds.
Tap a split to mark it uphill or downhill. The rest of the plan rebalances so the finish time holds.
| Mile | Terrain | Pace | Split | Clock |
|---|---|---|---|---|
| 1 | Flat | 7:30 | 7:30 | 7:30 |
| 2 | Flat | 7:25 | 7:25 | 14:54 |
| 3 | Flat | 7:19 | 7:19 | 22:14 |
| 3 + .11 | Flat | 7:14 | 0:46 | 23:00 |
Goal time. The time you want to beat. Add a stretch time if there is a faster one you are hoping for and the plan shows both, so you know on the course whether the better day is still on.
Strategy. Even pace is the fastest way to run a flat race if you can hold it; most people cannot, so the first mile is where goals die. A negative split starts a few seconds a mile slower than average and brings the pace down through the race. A fast finish holds a steady pace and spends what is left over the closing miles. The slider sets how big the difference is.
Terrain. Tap a split and mark it uphill or downhill. The calculator slows the climbs and speeds the descents by a fixed amount per mile, then rebalances every split so the total is still your goal. Effort stays level; pace does not.
Uphill costs more than downhill gives back. Studies on grade and running economy put the cost of climbing near 1.5 times what the same descent returns, which is why a hilly course is slower than a flat one even when it starts and finishes at the same height. The adjustments here are deliberately modest: about fifteen seconds a mile for a steady climb, thirty-five for a steep one, and ten and twenty seconds back for the descents.
Negative splits are how most records are run. The men’s and women’s marathon world records, the fastest 10,000 m races and almost every championship distance final close faster than they open. The plan is a target, not a rule; the race decides.
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