Endurometry
Set the goal from a nearby race, not a linear doubling. 10K 48:30 → 5K 23:23 and half 1:47:32 (Daniels). Even splits still win; the first kilometre of a 5K is where most people give the race away.
Last updated October 5, 2026
Shorter than a marathon, the same rule holds: the goal comes from a race you have run, and the first kilometre should not be a time trial. Scale with the race time predictor. Models: prediction explained.
Worked goals (same engine as the tool)
| Known | 5K Daniels | 10K | Half |
|---|---|---|---|
| 10K 48:30 | 23:23 (4:41/km) | 48:30 | 1:47:32 (5:06/km) |
| 10K 40:00 | 19:18 (3:52/km) | 40:00 | 1:28:33 (4:12/km) |
| 5K 25:00 | 25:00 (5:00/km) | 51:53 (5:11/km) | 1:55:04 (5:27/km) |
Linear doubling of a 25:00 5K is 50:00 for 10K. Daniels is 51:53 because 10K is not two 5Ks at the same speed. 1.10 from that 5K gives a 53:35 10K — a cautious bound, not a 5K target (1.10 shortens shorter races).
5K: do not sprint the first 400 m
Most 5K blow-ups are a 3:40 first kilometre on a 4:41 goal. The clock cannot give that time back. Even or a first km 2–3 seconds slower than goal is the repeatable plan. Official distance is 5.000 km. Convert the finish to splits on the pace calculator.
10K: settle by kilometre two
The 10K rewards the same discipline as the marathon, compressed. If km 1 is 15 s fast, you will pay from km 7. A 50:00 10K is 5:00/km — the same even pace as a 25:00 5K, but it is a harder 5:00 because of duration. Use a recent 5K or half to set the number; do not assume 2 × 5K.
Half: last row is 21.0975 km
A 1:47:32 half is 5:06/km even. The final label is 21.0975 km, not 21 and not 42.195. A 2:00 half is 5:41/km — same pace as a 4:00 marathon, different fatigue. Print the 22-ish rows (21 full km + remnant) or wear a pace band. How to build the table: race splits.
Related Tools
Race Time Predictor
Predict your finish time at any distance using the Riegel power law and the Daniels–Gilbert VO2max model.
Running Pace Calculator
Enter distance and finish time to get your pace per km and mile, average speed and per-kilometre splits.
Printable Pace Wristband
Generate a single-column pace wristband sized to your wrist — no cutting, just wrap it once. Pick even / negative / positive split and 1/2/5/10 km (or mi) intervals, then print at 100%.
Related guides
Race time prediction explained
How Endurometry scales a known race to another distance: Daniels–Gilbert as the headline, Riegel 1.06 as a check, 1.10 as a cautious longer-race bound.
How to Calculate Race Splits
Turn a goal finish into cumulative kilometre or mile splits, including the leftover 42.195 km row, and how that differs from a wrist pace band.
How the numbers are calculated
Frequently Asked Questions
Should I negative-split a 5K?
A tiny negative (first km a couple of seconds slow) works. A planned surge after 3 km only works if you did not already empty the tank.
Why is the predicted 10K slower than 2 × 5K?
You cannot hold 5K pace for twice the time. Daniels and Riegel both add that cost. 25:00 → 51:53, not 50:00.
Can I use 1.10 for a 5K goal?
No. From a 10K, 1.10 makes the 5K faster than Daniels (22:38 vs 23:23 from 48:30). Use 1.10 for longer targets.
Half vs marathon at 5:41/km?
Same even pace, not the same race. A 2:00 half scales to about 4:07 marathon (Daniels), not 4:00.
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