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Heart Rate Zones Formula: How to Calculate Your Five Zones

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To calculate heart rate zones, estimate your maximum heart rate (HRmax), then multiply it by the percentage range of each zone. The simplest version is 220 minus your age, with zone 1 at 50–60% of that number and zone 5 at 90–100%, as described in the Cleveland Clinic’s explanation of the five zones. A more personal version, the Karvonen formula, also uses your resting heart rate. Both are estimates, and this guide shows the arithmetic, a worked example, and how far the numbers can be off.

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TL;DR

  • Step 1: estimate HRmax. 220 minus age is the common shortcut; Tanaka (208 minus 0.7 × age) is a frequently recommended alternative.
  • Step 2: multiply HRmax by each zone’s percentage range (zone 1 at 50–60%, zone 5 at 90–100%).
  • Step 3 (optional): use the Karvonen formula, which adds resting heart rate: resting + intensity × (HRmax − resting).
  • Age-based HRmax formulas can miss an individual’s true value by 10–12 beats per minute (bpm) or more, so treat zones as a starting range, not a verdict.
  • If you have a heart condition or take medication that affects heart rate, ask a health professional for your target range before using any formula.

Table of Contents

Step 1: Estimate your maximum heart rate

Every zone calculation starts from HRmax, the highest rate your heart can reach during all-out effort. The most reliable way to learn it is a supervised exercise test. Without one, you estimate it from age.

The formula most people know is 220 minus age. It is also the one with the weakest footing: a 2022 review in Folia Cardiologica notes that it is not supported by scientific research and first appeared in medical literature in 1971. It survives because it is easy to compute, not because it fits people well.

Common max heart rate formulas

Several other equations exist. The Tanaka formula is described by HealthLink BC as accurate regardless of gender or current activity level. A 2024 review of exercise-testing formulas lists Robinson, Londeree and Fairbarn equations alongside it.

Formula Equation HRmax at age 20 HRmax at age 40 HRmax at age 60
Classic 220 − age 200 180 160
Tanaka 208 − 0.7 × age 194 180 166
Robinson 212 − 0.77 × age 197 181 166
Londeree 206 − 0.7 × age 192 178 164
Fairbarn 208 − 0.8 × age 192 176 160

The values above are our own arithmetic from the published equations, rounded to the nearest beat. Two patterns stand out. Around age 40 the formulas agree within about 5 bpm. At the ends of the age range they diverge: the classic formula gives a 60-year-old 160 bpm, while Tanaka gives 166. The classic formula therefore tends to put young adults higher and older adults lower than the alternatives.

If you need your exact age on a given date for the calculation, the chronological age calculator returns it in years, months and days.

Why a formula is only an estimate

Age-predicted equations carry a standard deviation of roughly 10–12 bpm and can overestimate or underestimate an individual’s HRmax. A 2022 paper on physical activity and cardiorespiratory fitness gives the same ±10–12 bpm variability for 220 minus age. Researchers reviewing stress-test formulas add that HRmax can vary by 20–30 bpm among people of the same age.

Some models add body mass, BMI, VO2max or sex and reduce prediction error slightly, according to Lach et al. (2022). The same authors point out that the remaining difference can still matter for elite athletes planning performance. For most recreational exercisers, the practical reading is simple: pick one formula, use it consistently, and adjust by how the effort feels.

Step 2: Turn HRmax into five zones

The five-zone model divides your range into bands of effort. According to the Cleveland Clinic, the zones run from 50–60% of maximum heart rate for zone 1 up to 90–100% for zone 5. Harvard Health describes the same structure, with zone 1 as recovery and zone 5 as maximal effort. The three middle zones are commonly split in 10-point steps between those two ends, which is the layout used below.

The calculation for each zone is:

  • Lower limit = HRmax × lower percentage
  • Upper limit = HRmax × upper percentage

Worked example: HRmax of 180

Take a 40-year-old. By the classic formula, HRmax is 220 − 40 = 180 bpm (Tanaka gives the same number at this age).

Zone Effort % of HRmax Range at HRmax 180
1 Recovery, warm-up 50–60% 90–108 bpm
2 Light, aerobic endurance 60–70% 108–126 bpm
3 Moderate 70–80% 126–144 bpm
4 Hard 80–90% 144–162 bpm
5 Maximal 90–100% 162–180 bpm

The Cleveland Clinic also notes that zone 5 is known as anaerobic, while zone 2 is aerobic or endurance work in which the body uses fat as a fuel source. The percentage arithmetic is easy to do by hand, but if you want to check a few multiplications quickly, the Percentage Calculator handles them in the browser without an account.

The three-zone alternative

You will meet a different layout in research papers. The three-zone model is the most common in scientific literature, and its boundaries are built around lactate threshold, which averages about 85% of maximum heart rate. Public health bodies use yet another grouping: HealthLink BC gives 45–54% for light, 55–69% for moderate and 70–89% for high-intensity activity.

Applied to the same HRmax of 180:

Intensity band % of HRmax Range at HRmax 180
Light 45–54% 81–97 bpm
Moderate 55–69% 99–124 bpm
High 70–89% 126–160 bpm

The numbers differ from the five-zone table because the models draw their lines in different places. That is not an error in either one. When a watch, an article and a coach each give you different boundaries, check which model each uses before comparing.

Step 3: Add resting heart rate with the Karvonen formula

The percentage method ignores how fit you are. Two people of the same age get identical zones even if one has a resting pulse of 50 and the other 75. The Karvonen method, also called heart rate reserve (HRR), adjusts for this. Harvard Health explains that it uses resting heart rate to make a more personalized estimate of target zones.

The formula, as given by the American College of Sports Medicine’s journal, is [(HRmax − HRrest) × percentage as a decimal] + HRrest](https://journals.lww.com/acsm-healthfitness/fulltext/2023/11000/estimating_maximal_heart_rate.4.aspx). Written another way: resting rate + intensity × (HRmax − resting rate).

How to measure resting heart rate

Harvard Health advises taking it first thing in the morning, before getting out of bed. The American Heart Association describes checking your pulse manually or with a wearable. Taking a few mornings in a row and using the typical value gives a steadier input than a single reading.

Man checking his resting pulse in bed

Worked example: HRmax 180, resting 60

Heart rate reserve is 180 − 60 = 120 bpm. For each zone boundary, multiply 120 by the percentage and add 60:

Boundary Calculation Result
50% 120 × 0.50 + 60 120 bpm
60% 120 × 0.60 + 60 132 bpm
70% 120 × 0.70 + 60 144 bpm
80% 120 × 0.80 + 60 156 bpm
90% 120 × 0.90 + 60 168 bpm
100% 120 × 1.00 + 60 180 bpm

Compare the 60–70% band: the plain percentage method gave 108–126 bpm, while Karvonen gives 132–144 bpm. The Karvonen numbers are higher because the method measures intensity as a share of the reserve, not of the total. Neither is the “right” one in isolation. The two methods express different definitions of 60%, so use the same one every time you compare sessions. The ACSM article summarizes the distinction: the %HRmax method needs maximum heart rate only, while %HRR also requires resting heart rate.

Quick method: do the calculation in four lines

  1. Subtract your age from 220, or compute 208 − (0.7 × age).
  2. Multiply the result by 0.5, 0.6, 0.7, 0.8, 0.9 and 1.0 to get the zone boundaries.
  3. If you know your resting rate, repeat with the Karvonen formula and compare the two tables.
  4. Check the zones against effort: zone 2 should feel conversational, zone 4 hard, zone 5 only sustainable briefly.

Using zones in real training

The point of zones is intent as much as intensity. The National Academy of Sports Medicine frames it this way: different zones trigger specific physiological adaptations, so the zone you pick should match the goal of the session.

A practical way to use this, as a general pattern and not a prescribed plan:

  • Easy days sit in zones 1–2, where you can hold a conversation.
  • Steady sessions use zone 3 for a sustained, moderate effort.
  • Hard intervals use zones 4–5 in short blocks with recovery between them.

Beginners should aim for the lower end of their range. The American Heart Association advises starting at about 50% and building intensity gradually. The Cleveland Clinic adds that because people have different work capacities, caution is wise when targeting the higher zones.

Pairing zones with pace

Heart rate lags behind effort, rises with heat and fatigue, and can drift during long sessions, so many runners cross-check it against pace. If you run, a pace calculator turns a goal time into splits you can compare with your zone readings. We have calculators for the 5K, the 10K, the half marathon and the marathon, plus a swim pace calculator for per-100 splits. Swimmers often see lower heart rates in water at the same effort, which is one reason a single land-based formula should not be applied blindly. A guide to reading heart rate charts from workouts shows how five-zone and three-zone models appear in the readings from fitness wearables.

When the formula does not apply

An estimate can be too high or too low, and the result is a target range that is either too hard or too easy to produce a training effect, as the ACSM article notes. It also lists medications among the factors that affect the estimates.

The most important case is beta-blockers. Beta-blockers and some calcium channel blockers can markedly blunt the rise in heart rate during exercise. The American Heart Association notes that some medications can lower maximum heart rate and target zones. If you take heart or blood pressure medication, or have a heart condition, ask your doctor or another health professional for your own target range, because a formula built on population averages cannot account for it.

If your heart rate runs higher than you intended during exercise, the AHA’s advice is straightforward: slow down. Chest pain, dizziness or unusual breathlessness are reasons to stop and seek medical advice, not to push through a zone.

Doing the math with GizmoBench

GizmoBench is a collection of free browser tools that run locally, with no account or installation. We do not currently list a dedicated heart rate zone calculator, so the steps above are written to be done with a pencil or a spreadsheet. For the supporting arithmetic, the Percentage Calculator and the other everyday tools work directly in the browser, and the body fat percentage calculator is there if you track other fitness numbers alongside your training. Core tool functions are free and need no sign-up.

FAQ

Is 220 minus age accurate?

It is a rough guide. Studies put the typical error of age-based formulas at 10–12 bpm, and individual HRmax can differ by 20–30 bpm from people of the same age. It works as a starting point for setting zones, not as a measurement of your true maximum.

What is the best way to calculate your heart rate zone?

A supervised exercise test gives the most reliable HRmax. Without one, use an age formula such as Tanaka, then add your resting heart rate through the Karvonen formula for a more personal estimate. Whichever you choose, keep it consistent and check the numbers against how hard the effort feels.

Which max heart rate formula should I use?

Tanaka (208 − 0.7 × age) is often recommended over 220 minus age, especially for people well below or above 40, where the two formulas diverge most. Around age 40 the common formulas land within a few beats of each other, so the choice matters less there.

What heart rate is too high during exercise?

There is no single number, since it depends on your age, fitness and medication. If your rate is higher than your target range, slow down. If you have a heart condition or take medication that affects heart rate, ask a health professional what your rate should be.

Sources