Tools
Heart Rate Zone Calculator
Find your five training zones three ways: from max heart rate, heart rate reserve, or lactate threshold.
Enter your heart rate above to see your five training zones.
Train in the right zone without thinking about it
Connect your Garmin and Coach Icarus assigns every session to the right zone for your fitness — and moves the zones as you improve.
Get Started FreeWhy Zones Differ by Method
Every zone method is trying to divide the same thing — your range of effort — into useful slices. Max heart rate percentages are the simplest: 60–70% is zone 2, 90–100% is zone 5. But two runners with the same max can have very different fitness, and the method cannot see that.
Heart rate reserve (the Karvonen method) fixes this by subtracting resting heart rate first: zones become percentages of the range you actually use. A fitter runner with a lower resting HR gets zones that reflect their larger aerobic range.
Lactate threshold HR goes further — it anchors zones to the point where effort shifts from sustainable to unsustainable, which you can measure with a 30-minute time trial. For runners who train with structure, this is the method worth the trouble.
Whichever you use, remember what the zones are for: keeping easy days easy and hard days hard. The exact boundary between zone 2 and zone 3 matters less than the discipline of staying out of the grey middle on easy days.
Frequently Asked Questions
What are the five heart rate training zones?
Zone 1 (recovery, very easy), Zone 2 (aerobic base, easy and conversational), Zone 3 (tempo, comfortably hard), Zone 4 (threshold, hard but sustainable), and Zone 5 (VO2max, very hard intervals). Each zone trains a different energy system — which is why easy days and hard days should feel clearly different.
Which method is most accurate: max HR, HR reserve, or threshold?
Lactate threshold HR is the most training-relevant because it anchors zones to a measurable physiological point rather than an estimate. HR reserve (Karvonen) accounts for your fitness level via resting HR and beats plain max-HR percentages for most runners. Max HR alone is the roughest — fine as a starting point, not as a final answer.
Is 220 minus age accurate for max heart rate?
Not really — it is a population average with an error margin of 10–20 beats for individuals. A better estimate comes from a hard effort: your highest observed heart rate in a race finish or hill repeats. Lab testing is the gold standard, but observed max beats the formula for almost everyone.
What heart rate is zone 2?
Roughly 60–70% of max heart rate, or 60–70% of heart rate reserve — but the practical check is the talk test: you should be able to speak in full sentences. If the formulas and your breathing disagree, trust your breathing.
How often should I retest my zones?
Every 8–12 weeks, or whenever your fitness clearly changes — easy pace dropping at the same heart rate is a sign your zones have shifted. Resting HR trending down over weeks is another signal that your aerobic base has grown and zones deserve a refresh.