Your heart rate runs lower on the bike and lower still in the water: less muscle mass is working, you’re horizontal and the water cools you. Triathletes should use separate zones for each sport.
How to use the Triathlon Target Heart Rate Calculator
- Age (years)
- Measured running maximum heart rate (0 = estimate)
- Resting heart rate (bpm)
- Sport
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Enter your age or measured maximum heart rate and your resting heart rate, then choose the sport.
Tips
- Practise transitions – they count towards your total time.
- Train your race-day nutrition as carefully as your fitness.
- Heart rate zones differ slightly between swimming, cycling and running.
- Everything is calculated in your browser.
Common mistakes to avoid
- Going too hard on the bike and suffering on the run.
- Trying new food or gear on race day.
- Ignoring open-water skills.
Inputs explained
| Field | What to enter |
|---|---|
| Age (years) | A number |
| Measured running maximum heart rate (0 = estimate) | A number |
| Resting heart rate (bpm) | A number |
| Sport | Choose one: Running, Cycling, Swimming |
What each result means
- Heart rate reserve = [Maximum heart rate for this sport] – [Resting heart rate (bpm)]
- Zone 1 – Recovery (50–60%) from = round([Resting heart rate (bpm)] + 0.5×[Heart rate reserve])
- up to = round([Resting heart rate (bpm)] + 0.6×[Heart rate reserve])
- Zone 2 – Endurance (60–70%) from = round([Resting heart rate (bpm)] + 0.6×[Heart rate reserve])
- up to = round([Resting heart rate (bpm)] + 0.7×[Heart rate reserve])
- Zone 3 – Tempo (70–80%) from = round([Resting heart rate (bpm)] + 0.7×[Heart rate reserve])
- up to = round([Resting heart rate (bpm)] + 0.8×[Heart rate reserve])
- Zone 4 – Threshold (80–90%) from = round([Resting heart rate (bpm)] + 0.8×[Heart rate reserve])
- up to = round([Resting heart rate (bpm)] + 0.9×[Heart rate reserve])
- Zone 5 – VO₂ max (90–100%) from = round([Resting heart rate (bpm)] + 0.9×[Heart rate reserve])
- up to = round([Resting heart rate (bpm)] + 1.0×[Heart rate reserve])
Example values
How the main result changes when Age changes and everything else stays at the example values above:
| Age (years) | Zone 2 – Endurance (60–70%) from (bpm) |
|---|---|
| 17.5 | 139 |
| 26.25 | 136 |
| 35 | 132 |
| 43.75 | 128 |
| 52.5 | 125 |
| 70 | 117 |
Formula
Target = RHR + % × (HRmax − RHR) · Cycling HRmax ≈ run HRmax − 5 bpm · Swimming HRmax ≈ run HRmax − 12 bpm
Worked example
Inputs — Age (years): 35; Measured running maximum heart rate (0 = estimate): 0; Resting heart rate (bpm): 55; Sport: Running.
Results — Maximum heart rate for this sport = 184 bpm; Heart rate reserve = 129 bpm; Zone 1 – Recovery (50–60%) from = 119 bpm; up to = 132 bpm; Zone 2 – Endurance (60–70%) from = 132 bpm; up to = 145 bpm; Zone 3 – Tempo (70–80%) from = 145 bpm; up to = 158 bpm; Zone 4 – Threshold (80–90%) from = 158 bpm; up to = 171 bpm; Zone 5 – VO₂ max (90–100%) from = 171 bpm; up to = 184 bpm.
Key terms
- Karvonen
- Zones using heart rate reserve.
Frequently asked questions
Why are swimming zones lower?
Horizontal position, cool water and less muscle mass lower your heart rate.
Can I use running zones on the bike?
They'll be about 5–10 bpm too high.
Which zone for long training?
Zone 2 builds endurance efficiently.
Should I race by heart rate?
It helps in long races; also use pace and power.