Zone 2 heart rate calculator
Enter your age. Add your resting heart rate if you know it, because it makes the answer meaningfully more accurate. You'll get your zone 2 range under both definitions people mean by "zone 2", which are not the same thing and differ by about 15 beats.
Your full five-zone table
The two definitions, and why they disagree
"Zone 2" means two different things depending on who is talking, which is why your watch, your coach, and a podcast can all give you different numbers.
The five-zone model (your watch)
Garmin, Polar, Coros and most fitness apps split your range into five zones by percentage of maximum heart rate. Zone 2 is 60 to 70% of max, sitting between "very light" and "moderate". This is the number your watch shows, and it's the second band in the table above.
The three-zone model (the training literature)
Exercise physiologists more often use three zones divided by two lactate thresholds. Here zone 2 means everything below your first lactate threshold, the highest intensity you can hold while lactate stays flat. In heart rate terms that usually lands around 70 to 80% of max.
When Peter Attia or Iñigo San Millán talk about zone 2, or when a polarized training plan says "80% of your volume in zone 2", this is the one they mean. It is a genuinely higher intensity than your watch's zone 2, and training at the lower number will feel suspiciously easy.
Neither is wrong. They're different maps of the same territory. If you're following your watch, use the first number. If you're following a polarized or 80/20 plan, use the second.
How the calculator works
Estimating maximum heart rate
Unless you enter a known value, your max is estimated from your age. The old 220 minus age rule is still the most famous and the least accurate; it was never derived from a proper study and carries a standard deviation of about 10 to 12 beats.
This calculator defaults to Tanaka: 208 minus 0.7 times age, from a 2001 meta-analysis of 351 studies, which is more accurate across adult ages. If you select female, it uses Gulati: 206 minus 0.88 times age, derived from a study of 5,437 women, because the standard formulas systematically overestimate maximum heart rate in women.
All three are population averages. Real individual maximums scatter widely around them, so if you have a number from a genuine all-out effort or a lab test, enter it. It beats any formula.
Why resting heart rate improves the answer
With a resting heart rate, the calculator switches to the Karvonen method, which works from heart rate reserve rather than raw maximum:
- Heart rate reserve = max HR − resting HR
- Target = (heart rate reserve × zone %) + resting HR
This matters because two people with the same max can have very different resting rates, and the fitter one is doing more work at any given percentage. Karvonen accounts for that; a flat percentage of max does not. The numbers it produces run higher, and for most people they're closer to how the effort actually feels.
Why your Garmin's zones may not match this
Garmin calculates your zones from whichever max heart rate is stored in your user profile, and by default that's the same age-based estimate you'd get here. If you've never corrected it, your watch is using a guess.
Garmin can also set zones from lactate threshold heart rate rather than max, if your device has detected one, which produces a different and usually better split. You can check which basis is in use under User Settings, and change the max to a real number if you have one.
So a mismatch between this page and your watch almost always comes down to one of three things: a different max heart rate in your profile, a percentage-of-max split versus a threshold-based split, or your device using heart rate reserve when this page isn't, or the reverse.
Checking it against how you feel
Formulas give you a starting range, not a verdict. Two checks tell you whether the number is right for you.
The talk test is the reliable one. In the five-zone version of zone 2 you should be able to hold a full conversation in complete sentences. In the three-zone version you can still talk, but you'd rather not, and sentences get shorter. If you're gasping, you're above it regardless of what the number says.
The drift check is the other. On a flat hour at a steady pace, your heart rate should stay roughly level. If it climbs more than about 5% over the hour while your pace holds, you started too hard and you're above your first threshold.
Nothing leaves your browser here. The maths runs locally as you type.
Your watch already knows your real numbers.
Skip the estimates. Connect Garmin to Claude or ChatGPT and ask what your actual zone distribution looked like this month, whether your easy runs are genuinely easy, and where your heart rate drifted.