20K Pace Calculator

20K pace calculator. Use a 20K time to estimate half marathon pacing and generate VDOT-style training paces.

A 20K is close enough to a half marathon to guide long-run pacing and threshold workouts.

Half-marathon-adjacent benchmark
Great for long-run targets
Training zones included

Training pace reference

Training paces by recent 5K time (min/km)
5K time	VDOT	Easy	Marathon	Threshold	Interval	Rep
15:00	69.6	3:45–4:30	3:23–3:42	3:15	2:56	2:32
17:30	58.2	4:20–5:12	3:54–4:17	3:46	3:23	2:56
20:00	49.8	4:54–5:53	4:26–4:51	4:16	3:51	3:19
22:30	43.4	5:29–6:34	4:57–5:25	4:46	4:18	3:43
25:00	38.3	6:03–7:14	5:28–5:59	5:16	4:45	4:06
27:30	34.2	6:37–7:53	5:59–6:33	5:46	5:13	4:30
30:00	30.8	7:11–8:32	6:30–7:06	6:16	5:40	4:54
32:30	28.0	7:44–9:10	7:01–7:39	6:46	6:07	5:17
35:00	25.6	8:17–9:48	7:31–8:12	7:15	6:34	5:41

More pacing guides

Method and sources

The numbers on this page are computed with the same code as the TrainPace calculators, from these published methods. They are training guidance, not medical advice.

Daniels, J. Daniels' Running Formula. Human Kinetics — VDOT, training zones, and equivalent race times.
Daniels, J. & Gilbert, J. (1979). Oxygen Power: Performance Tables for Distance Runners — the oxygen-cost and %VO2max equations behind VDOT.

Other TrainPace tools

For AI agents

Every public page on this site has a Markdown mirror at the same path with a .md suffix (for example /calculator.md), and honors an Accept: text/markdown request header on the HTML URL. The calculations here are also available as callable tools through a free public MCP server — no account or API key.