RRepWorks

Heart Rate Zone Calculator

Calculate your five heart rate training zones from your age or a measured max heart rate. Add your resting heart rate to use the more personalized Karvonen (heart rate reserve) method.

Max heart rate
years
bpm
Estimated max heart rate
187 bpm
Method
% of max HR
Add resting HR for more personalized zones
Z1
Recovery50–60%
Very easy — active recovery, warm-ups
94–112bpm
Z2
Endurance60–70%
Easy — conversational, aerobic base building
112–131bpm
Z3
Tempo70–80%
Moderate — comfortably hard, marathon effort
131–150bpm
Z4
Threshold80–90%
Hard — lactate threshold, 10K to half effort
150–168bpm
Z5
VO2 Max90–100%
Very hard — intervals, near-maximal efforts
168–187bpm

The five training zones explained

Heart rate zones divide effort into five bands so you can train each energy system on purpose instead of running every workout at the same medium-hard effort:

  • Zone 1 — Recovery (50–60%): very easy movement. Warm-ups, cool-downs, and recovery days after hard sessions.
  • Zone 2 — Endurance (60–70%): the base-building zone. You can hold a conversation. Most of your weekly volume belongs here.
  • Zone 3 — Tempo (70–80%): comfortably hard, roughly marathon effort. Useful in doses, but easy to overuse.
  • Zone 4 — Threshold (80–90%): the redline you can hold for about an hour at best. Tempo and cruise intervals here raise your lactate threshold.
  • Zone 5 — VO2 max (90–100%): short, hard intervals. Big fitness stimulus, big recovery cost.

%Max vs. Karvonen: which method should you use?

Percent-of-max is simple and fine for most people. The Karvonen method scales zones to your heart rate reserve (max minus resting), which better reflects actual effort — two athletes with the same max but resting heart rates of 45 and 70 are in very different shape, and Karvonen captures that. If you know your resting heart rate (check your watch first thing in the morning), enter it above for tighter zones.

Putting zones to work

The classic 80/20 rule: roughly 80% of training time easy (zones 1–2) and 20% hard (zones 4–5). If you're training for a race, pair your zones with a target from the race time predictor and translate hard-day efforts into splits with the pace calculator. Lifters can use zones too — keeping conditioning work in zone 2 protects recovery for heavy sessions planned around your one rep max.

These calculations are estimates for healthy adults, not medical guidance. Talk to a doctor before intense training if you have a heart condition or take medication that affects heart rate.

Frequently asked questions

What is zone 2 heart rate?

Zone 2 is 60–70% of your max heart rate (or heart rate reserve with the Karvonen method) — an easy, conversational effort. It's where most endurance athletes spend the majority of their training because it builds aerobic capacity with minimal fatigue.

How do I find my real max heart rate?

Age formulas are estimates with a spread of ±10–12 bpm. For a measured value, check the highest reading from a hard race finish or do a field test: after a thorough warm-up, run 2–3 hard hill repeats of 2 minutes, going all-out on the last one. Use the peak number as your max, and select 'I know my max' in the calculator.

What is the Karvonen formula?

Karvonen bases zones on heart rate reserve — the range between your resting and max heart rate: target = resting HR + (max HR − resting HR) × intensity%. Because it accounts for your resting heart rate, it personalizes zones better than percentages of max alone, especially for fitter athletes with a low resting HR.

Why does my easy pace feel too slow in zone 2?

That's normal, especially for newer runners — staying truly aerobic often means running slower than feels natural, and sometimes walking hills. As your aerobic base develops over weeks and months, your pace at the same heart rate gets faster. That improvement is exactly what zone 2 training builds.

More calculators

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Race Time Predictor
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One Rep Max
Estimate your one rep max (1RM) for squat, bench press, deadlift, or any lift from a submaximal set. Uses Epley, Brzycki, Lombardi, and O'Conner formulas with a full percentage table.