Training Paces Calculator (Jack Daniels)
What speed should you run for each training session?
Enter your reference time (5k, 10k, half marathon, marathon or other distance) to automatically get your E / M / T / I / R zones. Paces are based on VDOT percentages popularized by Jack Daniels.
Who is Jack Daniels?
Jack Daniels is an American physiologist and coach born in 1933. Former Olympic medalist in modern pentathlon, he is best known for his work on VDOT, a scientific approach that links oxygen consumption and running performance. His book Daniels' Running Formula is a reference for structuring training plans for runners of all levels.
- Doctor in exercise physiology, specialist in endurance sports.
- Coach of numerous NCAA and Olympic athletes since the 1970s.
- Creator of E / M / T / I / R zones that help balance volume and intensity.
Example paces: 10K in 45:00 (VDOT ≈ 44)
| Zone | Pace | Speed | % VO₂max | Typical use |
|---|---|---|---|---|
| E – Easy | 9:27 – 10:08/mi | 5.9 – 6.3 mph | 65 – 78% | Easy runs, recovery |
| M – Marathon | 8:22/mi | 7.2 mph | 80 – 84% | Long tempo runs |
| T – Threshold | 7:49/mi | 7.7 mph | 88 – 92% | Tempo 20-40 min |
| I – Interval | 7:08/mi | 8.4 mph | 95 – 100% | 3-5 min reps |
| R – Repetition | 6:29/mi | 9.2 mph | > 100% | Fast 200-400 m reps |
Recommended weekly distribution (Jack Daniels)
| Zone | % of volume | Goal |
|---|---|---|
| E – Easy | 70 – 80% | Aerobic base, capillarization, recovery |
| M – Marathon | 5 – 10% | Marathon-pace confidence, effort management |
| T – Threshold | 8 – 12% | Raise lactate threshold |
| I – Interval | 5 – 8% | Develop VO₂max |
| R – Repetition | 2 – 5% | Running economy, neuromuscular speed |
Heart rate zones associated with paces
| Zone | % HRmax | BPM (HRmax = 185) | Feel |
|---|---|---|---|
| E – Easy | 65 – 79% | 120 – 146 | Easy conversation |
| M – Marathon | 80 – 85% | 148 – 157 | Smooth but sustained |
| T – Threshold | 86 – 92% | 159 – 170 | Controlled, demanding |
| I – Interval | 93 – 100% | 172 – 185 | Hard breathing |
| R – Repetition | — | — | Max effort, full recovery between |
BPM values shown for a HRmax of 185 bpm (example). Calculate your precise HRmax to personalize these zones.
Frequently asked questions about training paces
What is VDOT and how is it calculated?
VDOT is an index created by Jack Daniels that estimates your functional VO₂max from a race time. For example, a 10K in 45 minutes corresponds to a VDOT of about 44. The higher your VDOT, the faster your training paces.
What is the difference between E, M, T, I, and R zones?
E (Easy): 65-78% VO₂max, aerobic base and recovery. M (Marathon): 80-84%, marathon-specific pace. T (Tempo/Threshold): 88-92%, lactate threshold. I (Interval): 95-100%, VO₂max development. R (Repetition): over 100%, speed and running economy.
What is the recommended weekly distribution between zones?
Jack Daniels recommends 70-80% of volume at easy pace (E), 10-15% at marathon and threshold pace (M+T), and 10-15% at high intensity (I+R). This distribution limits injury risk while promoting progress.
How do I use heart rate zones with training paces?
HR zones complement paces: E = 65-79% HRmax, M = 80-85%, T = 86-92%. For I and R, pace is more reliable than HR because the heart takes time to respond to short efforts. Calculate your HRmax for more precise targeting.
How often should I recalculate my training paces?
Recalculate after each reference race (roughly every 2-3 months) or after a significant training block. You can also predict your race times on other distances to update your VDOT.
How to read these paces?
- E (Endurance): 65–78% of your V̇O₂max, easy conversation.
- M (Marathon): 80–84% of your V̇O₂max, sustainable ~2–3 h.
- T (Tempo): 88–92%, controlled lactate effort.
- I (Interval): 95–100%, repetitions 3–5 min.
- R (Repetition): 105%+ critical speed, neuromuscular work.
These ranges come from Jack Daniels' VDOT tables. Adjust according to your experience, weather and fatigue.
Why use this calculator?
Daniels' paces directly link your race time to your training speeds to structure blocks (endurance, marathon, threshold, interval, repetition). This prevents training too fast or too slow, by basing your training load on an objective indicator: VDOT.
To optimize your training, you can also:
- Calculate your maximum heart rate to combine HR zones and paces
- Estimate your VO₂max to track your progress
- Convert your speeds and paces for your free runs
- Calculate your calories burned according to your training pace
- Adapt your paces based on temperature conditions
- Predict your race times on different distances
| Zone | Objective | Feeling / RPE |
|---|---|---|
| E | Aerobic base + recovery | Easy, fluid conversation (RPE 3–4) |
| M | Marathon specific | Smooth but sustained (RPE 5–6) |
| T | Improve lactate threshold | Controlled but demanding (RPE 7) |
| I | VO₂ max | Hard breathing (RPE 8–9) |
| R | Speed / running economy | Very intense, full recovery (RPE 9–10) |