Last updated: October 2026
Your 5 heart rate zones, explained
Short answer: the five zones are Recovery (50–60% — warm-up and easy days), Fat Burn (60–70% — conversational base building), Aerobic (70–80% — tempo), Threshold (80–90% — hard, lactate threshold) and Maximum (90–100% — all-out intervals). Your personal bpm ranges come from the calculator above.
| Zone | Intensity | Feels like | Best for |
|---|
| 1 · Recovery | 50–60% | Very easy, full sentences | Warm-up, cool-down, recovery days |
| 2 · Fat Burn | 60–70% | Easy, can chat | Base building, fat metabolism, endurance |
| 3 · Aerobic | 70–80% | Steady, deeper breathing | Tempo runs, cardio efficiency |
| 4 · Threshold | 80–90% | Hard, short phrases only | Speed, lactate threshold |
| 5 · Maximum | 90–100% | All-out, gasping | VO2 max intervals, sprint finish |
The Karvonen formula, with a worked example
Short answer: target heart rate = ((max HR − resting HR) × intensity) + resting HR. The (max − resting) part is your heart rate reserve — the range your heart actually has to work with.
Worked example with max 185 and resting 50: the reserve is 185 − 50 = 135 bpm. Zone 2 spans 60–70% intensity, so the lower bound is (135 × 0.60) + 50 = 131 bpm and the upper bound is (135 × 0.70) + 50 = 144.5, rounded to 145 bpm. Your Zone 2 is 131–145 bpm. Every other zone follows the same pattern — the calculator above shows the full worked formula for your numbers.
Why subtract resting HR at all? Because two runners with the same max of 185 are not equally fit if one rests at 45 and the other at 70. The fitter heart has a bigger reserve (140 vs 115 bpm), so its zones sit higher. Percentage-of-max ignores this and gives both runners identical zones — which is exactly why Karvonen is the default here.
Zone 2: why it's the most talked-about zone
Short answer: Zone 2 (60–70%) builds your aerobic base — better fat metabolism, more mitochondria, a higher ceiling for hard training — with low injury risk and fast recovery. Most coaches put ~80% of cardio time in Zones 1–2.
Zone 2 is the intensity where your body clears lactate as fast as it produces it, so you can sustain it for a long time. It is the backbone of endurance programs from marathon training to the popular "zone 2 cardio" trend: long, conversational sessions that make everything else faster. The classic mistake is drifting into Zone 3 on easy days — it feels productive but delivers neither true recovery nor true threshold stimulus. A heart rate monitor (or the talk test: full sentences = Zone 2 or below) keeps easy days honest.
Estimating max heart rate: 220 − age vs. the Tanaka formula
Short answer: 220 − age is a rough average (±10–12 bpm error); Tanaka's 208 − 0.7 × age fits measured data slightly better, especially after 40. A lab test or hard race effort beats both.
Both formulas describe population averages, not you specifically — genetics, training history and even heat shift your true max. Use an estimate to get started (tap "Estimate from age" above), then replace it the moment you have a measured number: the highest reliable reading from a hard 5K finish or a ramp test is far more trustworthy than any formula. Small errors in max HR shift every zone, so this is the single most impactful number on the page.
Why your zones differ from someone else's
Short answer: resting heart rate, fitness level, age and even medications move your zones — which is why a generic chart can't replace a personal calculation.
A trained endurance athlete might rest at 42 bpm while a sedentary peer rests at 75; with the same max of 180, the athlete's Karvonen Zone 2 is 125–139 bpm and the peer's is 103–114 bpm. Age lowers max HR over time, beta-blockers blunt it artificially, heat and dehydration raise heart rate at a given effort. Re-test your resting HR every few months (morning, before coffee) and nudge your max if race data suggests the estimate was off.
Frequently asked questions
What are my heart rate zones?
Your heart rate zones are five intensity bands expressed as percentages of your capacity: Zone 1 Recovery (50–60%), Zone 2 Fat Burn (60–70%), Zone 3 Aerobic (70–80%), Zone 4 Threshold (80–90%) and Zone 5 Maximum (90–100%). With the Karvonen method, each zone's bpm range is ((max HR − resting HR) × intensity) + resting HR. Enter your numbers in the calculator above to get your personal ranges — for example, max 185 and resting 50 gives a Zone 2 of 131–145 bpm.
How do I calculate heart rate zones without knowing my resting heart rate?
Use the simple percentage-of-max method: multiply your max heart rate by each zone's percentage. With a max of 185, Zone 2 (60–70%) is 111–130 bpm. It is less personal than Karvonen because it ignores fitness level — two people with the same max but different resting heart rates get identical zones — but it works when you don't know your resting HR. Switch the calculator above to "% of max HR" mode to use it.
What is Zone 2 heart rate, and why does everyone talk about it?
Zone 2 is 60–70% intensity — a pace where you can still hold a conversation. It is popular because it builds your aerobic base: it improves fat metabolism, grows mitochondria and raises the ceiling for harder training, all with low injury risk and fast recovery. Most coaches suggest roughly 80% of cardio time in Zones 1–2. With the Karvonen formula, Zone 2 = ((max HR − resting HR) × 0.60 to 0.70) + resting HR.
Karvonen vs. percentage of max — which method is better?
Karvonen is better for most people because it accounts for fitness via resting heart rate: a fitter person with a lower resting HR gets wider, more accurate zones. Percentage of max is simpler and fine as a starting point. The practical difference is largest in the lower zones — Karvonen Zone 2 for max 185 / rest 50 is 131–145 bpm, while % of max gives 111–130 bpm. The calculator above offers both so you can compare.
How accurate is 220 minus age for max heart rate?
220 − age is a rough population average with a typical error of ±10–12 bpm for individuals — fine for a first estimate, not precise enough to set exact zones. The Tanaka formula (208 − 0.7 × age) fits measured data slightly better, especially past 40. The best number comes from a lab test or a hard field effort (e.g., the end of a 5K race). If you know your true max, always use it instead of an estimate.
Should beginners train with heart rate zones?
Yes — zones are arguably most useful for beginners, because perceived effort is unreliable when you are new. Staying in Zone 2 keeps easy days genuinely easy, which is where most beginners go wrong (they run their easy days too hard). Start with mostly Zones 1–2 for the first 8–12 weeks, add Zone 3 tempo work once, then introduce short Zone 4–5 intervals only after a base is built.
Which heart rate zone burns the most fat?
Zone 2 (60–70%) burns the highest proportion of calories from fat, which is why it is called the fat-burn zone. But total calorie burn matters more for weight loss than the fuel mix — higher zones burn more calories per minute overall. The practical answer: build most of your cardio volume in Zone 2 for metabolic health, and add higher-intensity sessions for total energy expenditure.
