Tools · HR Zones
Heart rate zone calculator
Get all five training zones in seconds. Supports Karvonen, % Max HR, and MAF 180. Uses the Tanaka formula to estimate max HR — more accurate than 220 − age, especially past 40.
- Z1Recovery94–112 bpm50–60% HRmax
- Z2Aerobic Base112–131 bpm60–70% HRmax
- Z3Tempo131–150 bpm70–80% HRmax
- Z4Threshold150–168 bpm80–90% HRmax
- Z5VO2 Max168–187 bpm90–100% HRmax
Skip the estimates — use your real data.
Connect Garmin and Gneta pulls your actual zones from months of recorded workouts. No formulas, no guesses. AI coaching built on top.
How each method works
% Max HR
Zones are a percentage of your maximum heart rate. Simple — only needs your age. Zone 2 is 60–70%, threshold is 80–90%, and so on.
Zone HR = MaxHR × %Karvonen (HRR)
Uses heart rate reserve — the gap between resting and max. More personal: two athletes with the same max HR but different resting HRs get different zones.
Zone HR = (HRR × %) + RestHRMAF 180
Phil Maffetone's aerobic ceiling. Strict, conservative base-training cap. Most useful when paired with regular MAF tests over months.
MAF = 180 − age + adjustmentA word on accuracy
Every formula here is an estimate. Max HR varies by ±10–15 bpm between people of the same age, and it can't be predicted reliably from age alone. That's why the same 45-year-old can have a real max HR anywhere from 165 to 195.
Use these zones as a starting point. Validate them against real training (how you feel at each zone). For serious training decisions, either do a max HR field test or let your watch build a picture over weeks of workouts — that's what Gneta syncs.
Frequently asked questions
Is the 220 − age formula accurate?
No — it's off by ±10–15 bpm for most people. We use the Tanaka formula (208 − 0.7 × age) by default, which is measurably more accurate, but still only an estimate. A field test or lab measurement is the only way to know your real max HR.
Should I use % Max HR or Karvonen?
Karvonen (heart rate reserve) is more personalized because it factors in your resting HR. If you know your resting HR, use Karvonen. If you only know your age, % Max HR is a solid starting point.
What is MAF 180 and when should I use it?
MAF (Maximum Aerobic Function) was developed by Phil Maffetone. The formula 180 − age (with adjustments) gives you an aerobic HR ceiling for base training. Many endurance athletes use it as a strict cap for easy runs. It is intentionally conservative and works best combined with regular MAF testing.
How do I find my true max heart rate?
A supervised max HR test is the most accurate. A common field version: after a 15-minute warm-up, run 3 × 3-minute hard efforts up a hill with 2-minute jogs between. The highest HR you see in the final effort is close to your max. Talk to a coach or doctor before maxing out.
How do I find my resting heart rate?
Take it first thing in the morning, before getting out of bed, after a normal night's sleep. Count beats for 60 seconds. Do this for 5–7 days and take the average. A Garmin or similar device will track this for you overnight, which is usually more reliable.
How much training should I do in each zone?
Most endurance research supports an 80/20 split: about 80% of weekly training time easy (Zones 1–2) and 20% hard (Zones 4–5). Zone 3 is the "grey zone" — too hard to count as recovery, too easy to drive adaptation. Gneta tracks your polarization so you can see if you're drifting there.
Why does Gneta pull zones from Garmin instead of calculating them?
Because Garmin already knows your real max HR from months of data. Formulas are a starting point; measured data is the truth. Gneta syncs whatever zones you have configured on your watch or in Garmin Connect, and you can override them manually if you prefer.
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