CoreRise

Training · Zones

Heart Rate Zones Calculator: Max HR, LTHR & Karvonen

Enter your max heart rate or your lactate threshold heart rate and get all five training zones instantly. Supports the three most common methods: percentage of max HR, Joe Friel's LTHR-based zones, and the Karvonen heart rate reserve formula.

Antoine Boudet

Founder of CoreRise · Software engineer & IRONMAN® 70.3® finisher · Updated

Method

Enter a heart rate value to see your zones.

How the heart rate zones calculator works

There is no single universal heart rate zone model: there are several, each with its own assumptions. This calculator supports the three you will see in Garmin, TrainingPeaks, Polar, and coaching software.

Percentage of max HR is the simplest: Zone 1 is 50–60% of max HR, Zone 2 is 60–70%, Zone 3 is 70–80%, Zone 4 is 80–90%, Zone 5 is 90–100%. It's rough because max HR is an unreliable anchor: measured max is hard to reach and predicted max from 220 minus age is off by 10 beats or more for most people.

Joe Friel's LTHR-based zones are more precise for endurance athletes. Zone 1 is less than 85% of LTHR, Zone 2 is 85–89%, Zone 3 is 90–94%, Zone 4 is 95–99%, Zone 5a is 100–102%, Zone 5b is 103–106%, Zone 5c is over 106%. LTHR can be estimated from a 30-minute solo time trial (use the last 20 minutes' average HR).

Karvonen heart rate reserve (HRR) adjusts for resting heart rate, which anchors the bottom of the range. Target HR = ((max HR − rest HR) × intensity %) + rest HR. The zones map to the same 1–5 structure but account for fitter athletes having lower resting heart rates.

All three methods produce slightly different numbers. If you train by heart rate, pick one and stay with it: switching between methods mid-block makes the data incomparable.

% Max HR: HR = max HR × intensity · Friel LTHR: zones = % of LTHR · Karvonen: HR = ((max − rest) × intensity) + rest

Read the full guide: What is Zone 2 training?

Frequently asked questions

Which method should I use?
If you have a reliable LTHR from a recent time trial, use Joe Friel's LTHR-based zones. They are the most precise for endurance training. If you only know your max HR from a sprint finish or a race, use the percent of max HR method. Karvonen is most useful for athletes tracking fitness changes over months, because the adjustment for resting heart rate captures the parasympathetic adaptation that comes with fitness.
How do I find my max heart rate?
The 220-minus-age formula is unreliable: it has an error margin of ±10 to 12 beats. The best field test is the highest heart rate you have ever actually seen on a watch during a hard effort (finish of a race, final VO2max interval). Garmin's predicted max from training data is usually closer than the age formula but still ±5 beats. (CoreRise itself only uses 220 minus age as a starting default for brand-new profiles; the moment you enter a real max HR, your zones re-derive from it.)
How do I estimate my LTHR?
The simplest protocol: do a 30-minute solo time trial on flat ground (run or bike) after a proper warm-up. Take the average heart rate of the last 20 minutes. That number is a good approximation of your LTHR. Repeat every 6–8 weeks during hard training blocks.
Are these zones the same as Garmin's zones?
Garmin uses percent of max HR by default but lets you switch to lactate threshold or heart rate reserve in the device settings. If you want Garmin to agree with your coach, set the method to whatever your coach uses and enter the same anchor number.

CoreRise / Endurance training

Cora picks the right zones for you

Heart rate is only useful if the zones are honest. CoreRise pulls your resting HR from Apple Health, infers your threshold from your training files, and applies the method your coach would pick: LTHR for endurance blocks, HRR for sprint and strength-endurance work. You don't have to remember which formula to use.

Download on the App StoreRead the Learn hub

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Heart Rate Zones Calculator: Max HR, LTHR & Karvonen | CoreRise