Heart Rate Zones Calculator

Use this Heart Rate Zones Calculator to set training intensity in BPM

Most people who search for “heart rate zones” are trying to answer one practical question: what heart rate should I target during a workout? This calculator turns a simple input (your age) into a set of five training zones in beats per minute (BPM). If you already know your max heart rate, you can enter it to avoid using an estimate. If you also know your resting heart rate, the calculator can produce a more individualised set of zones using heart rate reserve (HRR), which often fits real training better than a pure percentage of max.

The output is meant for workout planning. It is not a medical tool and it does not diagnose anything. The zones here are aimed at endurance-style training and general fitness programming where you want a repeatable intensity target. If you are chasing a clinical “normal heart rate” interpretation, or you need condition-specific advice, this is the wrong tool.

To use it quickly, enter your age and tap Calculate. You will see your estimated max heart rate and a set of zone ranges. If you have a measured max heart rate from a lab test or a hard field test, add it and the calculator will use that instead. If you have a reliable resting heart rate (taken when relaxed, ideally in the morning), add it to unlock HRR-based zones. HRR zones shift the targets upward or downward based on how low your resting heart rate is, which can better reflect fitness differences between two people of the same age.

Assumptions and how to use this calculator

• If you do not enter a max heart rate, the calculator uses the common estimate: max HR = 220 − age.
• Zone bands are the standard five-zone model: 50–60%, 60–70%, 70–80%, 80–90%, and 90–100%.
• If resting heart rate is provided and valid, zones are calculated using Karvonen (HRR): target = (max HR − resting HR) × % + resting HR.
• All zones are shown as ranges in BPM and rounded to whole beats for practical use during training.
• This calculator assumes steady-state training targets; short, maximal sprint work can be poorly represented by heart rate due to lag.

Common questions

Should I use age-based max heart rate or a custom max heart rate?

If you have a measured or well-tested max heart rate, use it. Age-based max heart rate is a rough estimate and can be off by a lot for an individual. It is still useful when you have no better data because it gives you a consistent starting point. If your training feels obviously too easy or too hard in the suggested zones, that is a signal to find a better max HR estimate.

What is the difference between “% of max HR” and “HRR/Karvonen” zones?

% of max HR ignores resting heart rate. HRR zones incorporate it, which can better match how hard a given BPM feels for different people. Two people with the same max HR but different resting HR can have very different usable training ranges. If your resting heart rate input is accurate, HRR zones are usually the better personalisation.

How do I get a reliable resting heart rate?

Measure it when you are calm, not right after caffeine, stress, or exercise. Morning readings before getting out of bed are commonly used. If you only have smartwatch data, use an average of several quiet days rather than a single low or high value. If the number you enter is unrealistic for you, the zones will be distorted.

Which zone should I train in for fat loss or general fitness?

This tool does not prescribe programs. Practically, most beginners do well with a lot of time in lower zones that feel sustainable, with smaller doses of harder work once consistency is in place. Use the zones as intensity guardrails. If you cannot hold a conversation at all, you are likely in a higher zone. If your workout feels too easy to matter, you are likely too low for your goal.

Why does my heart rate not match the zone immediately when I change pace or effort?

Heart rate lags behind effort, especially with intervals, hills, heat, dehydration, and fatigue. Use zones as targets over minutes, not seconds. In short efforts you may need to pair heart rate with perceived exertion or pace/power. The zone ranges are still valuable for steady segments and for keeping easy days genuinely easy.