heart-rate-zone-calculator
A heart rate zone calculator computes the target beats-per-minute ranges for the five training zones — recovery (Z1), endurance (Z2), tempo (Z3), threshold (Z4), VO₂max (Z5) — using either the simple maximum-heart-rate formula (220 − age, or the Tanaka improvement 208 − 0.7·age) or the Karvonen method that adjusts for resting heart rate (HRR-based). The ZTools Heart Rate Zone Calculator surfaces both methods, lets you enter a measured max-HR if known (more accurate than predicted), and explains zone-by-zone what each range produces physiologically — so users train with intent rather than chasing arbitrary heart-rate targets.
Use cases
Designing a polarised training plan
80/20 polarised training: 80% in Z1–Z2, 20% in Z4–Z5, almost nothing in Z3. Calculator gives the exact bpm range for each zone.
Endurance base-building
Long aerobic runs sit in Z2. Knowing the exact range prevents "creeping up" into Z3 where most amateurs accidentally train.
High-intensity interval programming
Z5 intervals need clear targets. Calculator gives the upper bpm so intervals match the intended stimulus.
Recovery-day pacing
Easy days should stay in Z1. Calculator gives a hard ceiling so recovery is real.
How it works
- Enter age and resting HR — Age for max-HR estimation. Resting HR (measure on waking) for Karvonen method.
- Optional measured max-HR — If you have done a true max-HR test, enter it — overrides the predicted value (which has ±10–12 bpm error).
- Compute zones — Max-HR method: zones are 50–60%, 60–70%, 70–80%, 80–90%, 90–100% of max-HR. Karvonen: HRR = max − resting; zones are RHR + (HRR × pct).
- Read the ranges — Each zone shows lower / upper bpm and a one-line description (recovery, endurance, tempo, threshold, VO₂max).
- Use during training — Wear a chest strap or wrist monitor; aim for the target range during the prescribed effort.
Examples
Input: Age 30, resting HR 60
Output: Predicted max ≈ 187 (Tanaka). Z2 (60–70%): 112–131 bpm (max-HR) or 136–149 bpm (Karvonen)
Input: Age 40, measured max 180, RHR 55
Output: Z4 (80–90%): 144–162 bpm (max-HR) or 155–168 bpm (Karvonen) — Karvonen produces tighter, higher zones
Input: Age 50, RHR 70
Output: Predicted max 173 (Tanaka). Z2 RHR-based: 132–142 bpm
Frequently asked questions
How accurate is the 220 − age formula?
Standard error is ±10–12 bpm. Tanaka (208 − 0.7·age) is slightly more accurate. Both are population averages — individual max-HRs can deviate by 20+ bpm.
Should I do a max-HR test?
For serious endurance athletes, yes — a graded test under medical supervision, or a self-administered hill-repeat protocol, gives a much better max number.
Is Karvonen better than max-HR-percent?
Karvonen accounts for individual fitness (lower RHR shifts zones up). It is generally preferred by serious athletes; max-HR-percent is fine for beginners.
Why does my Z2 feel hard?
Either max-HR is overestimated, RHR is wrong, or you are in Z3 thinking it is Z2. True Z2 should feel "all-day pace" — easy enough to talk in full sentences.
Are five zones standard?
Roughly yes — 5-zone (Polar, Garmin) and 7-zone (Coggan power) frameworks both circulate. 5-zone is the simplest and most teachable.
Do zones shift with caffeine, sleep, stress?
Yes — heart rate response varies day-to-day. Use perceived exertion alongside HR; if HR is elevated for the same effort, ease back.
Tips
- Spend most volume in Z1–Z2 — the "polarised" model has the strongest evidence.
- Use a chest strap, not just a wrist monitor — wrist optical accuracy degrades during running.
- Recheck zones every 6 months — fitness changes shift the ranges.
- On hot days, expect higher HR for the same effort — do not push to "hit the number".
- Combine HR with perceived exertion; both signals together beat either alone.
Try it now
The full heart-rate-zone-calculator runs in your browser at https://ztools.zaions.com/heart-rate-zone-calculator — no signup, no upload, no data leaves your device.
Last updated: 2026-05-05 · Author: Ahsan Mahmood · Edit this page on GitHub