Heart rate zones turn a single number on your watch into a training plan. Instead of guessing whether that easy run was actually easy, or whether your intervals were hard enough, you train inside a band tied to what your heart is doing. This calculator estimates your maximum heart rate from your age and splits that maximum into five training zones — recovery, aerobic, tempo, threshold, and VO2 max — so you know exactly what each beat should be doing.
The default model uses the classic 220 minus age formula, which is the estimate the American Heart Association publishes for target heart rate guidance. If you also enter your resting heart rate (your pulse first thing in the morning before you get out of bed), the calculator switches to the Karvonen heart-rate-reserve method, which individualizes the bands to your actual fitness level.
How to Use
- Enter your Age in years. This drives the default estimate: maximum heart rate = 220 minus your age. A 30-year-old, for example, lands on an estimated max of 190 bpm.
- Pick a Max HR Formula. Leave it at "Standard (220 − age)" for the classic AHA estimate. Switch to "Tanaka (208 − 0.7 × age)" or "Gellish (207 − 0.7 × age)" for research-backed alternatives that often fit older adults and regular exercisers better. The choice shifts every zone up or down by a few beats.
- Optionally enter your Resting Heart Rate. Measure it on three or four mornings in a row before standing up, and use the average. Leave it at 0 to use plain percent-of-max zones.
- Read the result card. You will see your estimated max heart rate up top, followed by five bands — each zone shows a minimum and maximum beats-per-minute range.
- Match your session to a zone: Zone 2 for long easy aerobic work, Zone 3 for tempo runs, Zone 4 for intervals, and Zone 5 for short VO2-max efforts.
- Wear a chest strap or optical wrist monitor during the workout and compare your average heart rate to the band you targeted. If you spend most of the session in the wrong zone, adjust your pace or effort for next time.
The bands are standard across the industry: Zone 1 is 50–60% of max, Zone 2 is 60–70%, Zone 3 is 70–80%, Zone 4 is 80–90%, and Zone 5 is 90–100%. When you enter a resting heart rate, the Karvonen formula stretches each band around your actual reserve instead of anchoring everything to zero.
The Five Training Zones, Explained
- Zone 1 (50–60% max) — Recovery. Very light effort. You could hold a full conversation without pausing. Used for warm-ups, cool-downs, and active recovery days.
- Zone 2 (60–70% max) — Aerobic. The foundation zone. Easy enough to sustain for 60–90 minutes, but you are building mitochondrial density and fat-burning efficiency. Most of your weekly mileage should live here.
- Zone 3 (70–80% max) — Tempo / Moderate. Comfortably hard. You can talk in short sentences but not hold a conversation. This is where aerobic endurance is converted into race-pace comfort.
- Zone 4 (80–90% max) — Threshold / Hard. Your lactic threshold. You can hold this for 20–40 minutes in training. Intervals in this zone raise your lactate clearance.
- Zone 5 (90–100% max) — VO2 Max / Maximum. All-out. Sustained only for 1–5 minute repeats. This is the ceiling of your aerobic engine and is the hardest zone to recover from.
A common mistake is living in Zone 3 every day — fast enough to feel hard, slow enough to never fully stress the system, and too intense to be true recovery. Most athletes build faster by spending more time in Zone 2 and the occasional structured dip into Zone 4.
Examples
Example 1 — A 30-year-old runner. With age 30 and no resting heart rate entered, the calculator estimates a max heart rate of 190 bpm. Zone 2 lands at 114–133 bpm, Zone 3 at 133–152 bpm, and Zone 4 at 152–171 bpm. An easy long run should average 114–133; a threshold interval session should hover at 152–171.
Example 2 — A 40-year-old recreational cyclist. Age 40 gives a max heart rate of 180 bpm. Zone 2 becomes 108–126 bpm, Zone 3 126–144 bpm, and Zone 4 144–162 bpm. Notice how the entire spectrum shifts down ten beats across the board — age matters, and your watch default zone is probably stale.
Example 3 — Using the Karvonen method. A 30-year-old with a resting heart rate of 60 bpm has a heart-rate reserve of 190 minus 60 = 130 bpm. Zone 2 becomes 60 + (130 × 0.60) to 60 + (130 × 0.70), or 138–151 bpm — noticeably higher than the plain percent-of-max 114–133. A low resting heart rate means your engine is efficient, and the bands rise to match.
Example 4 — Stress magnitude. If you enter an unrealistic age such as 1,000,000, the calculator rejects the input instead of returning a nonsensical negative max heart rate. Age must be a realistic value between 1 and 120.
FAQ
What heart rate zone should I train in?
Most of your weekly training — 70–80% of it — should sit in Zone 2 (60–70% of max). This is the aerobic base zone where you build endurance without wrecking recovery. Add one or two sessions per week in Zone 4 (80–90%) for threshold intervals, and keep Zone 5 (90–100%) to short, occasional repeats. Zone 1 is for warm-ups and recovery days.
What is a good Zone 2 heart rate for my age?
Take 60–70% of your estimated max heart rate (220 minus age). For a 30-year-old with a max of 190 bpm, Zone 2 is 114–133 bpm. For a 40-year-old with a max of 180 bpm, Zone 2 is 108–126 bpm. If you use the Karvonen method with your resting heart rate, the numbers will shift upward.
Is the 220 minus age formula accurate?
It is a population average, not a personal measurement. Research (Tanaka, Monahan & Seals, 2001) suggests 208 minus 0.7 × age is slightly more accurate across adults, and Gellish (2007) offers 206.9 minus 0.67 × age. The 220 formula remains the most widely taught default and is close enough for zone training — if you want a true personal max, do a supervised graded exercise test.
What is the Karvonen method?
The Karvonen formula calculates target heart rate from your heart-rate reserve: max heart rate minus resting heart rate. Target = restingHR + (maxHR − restingHR) × percent. It is more individualized than plain percent-of-max because a fit person with a low resting heart rate has a larger reserve and a higher training target at the same percentage.
What is a normal resting heart rate?
For most adults, a resting heart rate between 60 and 100 bpm is considered normal. Trained endurance athletes often sit between 40 and 60 bpm, and elite distance runners can dip into the 30s. If your resting heart rate is consistently above 100 or below 40 and you feel off, check in with a doctor.
Why does my watch zone not match this calculator?
Watches ship with different zone defaults. Some use 5-zone models, others 3 or 7. Some anchor to max HR, others to lactate threshold pace or power. The percentages on this page follow the common 50/60/70/80/90/100 split used by the American Heart Association. If you disagree with the band, override it in your watch settings and copy the numbers here.
Can I train too much in Zone 4?
Yes. Zone 4 work is productive but expensive. Doing it every day leads to staleness, suppressed HRV, and stalled progress. Limit threshold and VO2-max sessions to one or two per week, separated by at least 48 hours, and keep the rest of the week in Zones 1–2.
Disclaimer
This heart rate zone calculator is provided for informational purposes only and is not medical advice. Heart rate estimates are population averages based on age and do not replace a graded exercise test or a clinician's assessment. Medications (including beta blockers), heart conditions, arrhythmias, pregnancy, heat stress, altitude, and illness can all shift your real working heart rate. If you have a known heart condition, are new to exercise, or are experiencing chest pain, dizziness, or unusual shortness of breath, stop and consult a qualified healthcare professional before following any training zone.