CalcVitalsTraining Pace Zones Calculator
Training paces all hang off your threshold — the pace you could hold for about an hour. From a 10K in 50:00 (5:00/km), threshold pace is about 5:08/km, easy runs belong at 6:25–6:55/km, and intervals at about 4:53/km. Enter any recent race and the full set is derived.
How it works
Jack Daniels' Running Formula organised modern training around a simple truth: different paces train different systems, and each has a correct dosage. This page derives his five paces from a single race result, using your threshold pace — roughly hour-race pace — as the anchor, with your 10K equivalent found via Riegel's formula when your race was another distance.
The zones, in plain terms. Easy (E) builds aerobic volume and recovery — the majority of your kilometres live here, slower than feels virtuous. Marathon (M) teaches fuel efficiency at goal pace. Threshold (T) — 'comfortably hard', sustainable about an hour — is the highest-value workout pace for most distance runners. Interval (I) develops VO2 max in 3–5 minute repetitions; Repetition (R) is short, fast economy work with full recoveries.
Recalculate from a fresh race every 6–10 weeks; fitness moves and the zones should move with it. And hold the numbers loosely in weather: heat, hills and wind all tax pace, so in hard conditions run the zone's effort and let the watch say what it says.
The method
Anchor: threshold pace = 10K pace × 1.025 (10K equivalent via Riegel when the race distance differs). E = T × 1.25–1.35; I = T × 0.95; R = T × 0.90; M from Riegel marathon prediction. Proportions follow Daniels-style zone relationships, simplified and stated openly.
Frequently asked questions
Why is easy pace so slow?
Because easy running's job is volume without breakdown: capillary and mitochondrial development happen at low intensity, and arriving fresh at the hard sessions is worth more than heroic easy days. Elite marathoners do most of their (very large) volume at paces far slower than their race pace.
How often should I run at threshold?
Once a week is the classic dose — 20–40 minutes total at T pace, in one tempo run or broken into cruise intervals. It should feel controlled, never like a race.
My race was on a hilly or hot day. Can I still use it?
You can, but the zones will come out conservative (based on a slower equivalent 10K). If the race plainly understates your fitness, use a recent hard time trial on a fair course instead.