Financial term · Reviewed August 17, 2026
Heart-rate reserve
Heart-rate reserve: The difference between maximum and resting heart rate. The Karvonen method uses it to scale a target training intensity to an individual's own range. The Target Heart Rate Calculator returns this figure from karvonen: target = (220 − age − resting HR) × intensity % + resting HR. At that calculator’s documented worked-example inputs the target heart rate is 149; holding every other input steady, moving age from 17.0 years to 53.0 years moves it from 136.4 to 161.6, a spread of 25.2.
The gap between resting and maximum heart rate is the range you actually train inside, and it differs person to person. Scaling intensity to that range personalises the target. A flat percentage of maximum ignores fitness entirely. So it sets zones too hard for a beginner and too easy for someone well trained.
| Term | Heart-rate reserve |
|---|---|
| Category | Fitness & Performance |
| How it is found | Karvonen: target = (220 − age − resting HR) × intensity % + resting HR |
| Worked example | Target heart rate: 149 |
| Computed by | Target Heart Rate Calculator |
| Related terms | 3 defined in this glossary |
Before you rely on it
What to check
Take resting heart rate properly, first thing, before getting up.
The common error
Where people go wrong with heart-rate reserve
Using an inflated resting figure taken during the day. That compresses the range and pushes every zone too high, so easy sessions stop being easy and the training stops working.
Worked through
Heart-rate reserve in plain numbers
A 30-year-old estimates a maximum heart rate at 190 beats per minute, using the common 220 minus age rule, and measures a resting rate of 60. Heart-rate reserve is 190 − 60 = 130. The Karvonen method sets a target by taking a share of that reserve and adding resting rate back. At 50% intensity the target is 60 + 0.5 × 130 = 125 beats per minute. At 70% it is 60 + 0.7 × 130 = 151. Someone with a lower resting rate gets a wider reserve and a different target, and it is a way of scaling effort to the person, not a prescription.
Easily confused
Heart-rate reserve and its neighbours
Heart-rate reserve is not maximum heart rate, resting heart rate or target heart rate. Maximum is the highest rate a person can reach. Resting is the rate at rest. Reserve is the difference. Target is the range chosen from the reserve for training, and the plain percentage-of-maximum method ignores resting rate, so it gives the same target to two people with different fitness levels. Formulas for maximum heart rate are population averages with wide individual variation, so a measured value is better when available.
In real decisions
Where heart-rate reserve turns up
Coaches and athletes use it to set training zones for endurance sessions. Fitness trackers and calculators apply it to guide effort. Cardiac rehabilitation programs use related measures, set by clinicians; it supports pacing on long runs or rides, helps avoid going too hard on recovery days and lets someone track fitness by watching resting rate fall over time. It is one of several tools for monitoring exercise effort.
Know the edges
Where heart-rate reserve stops being reliable
Estimates of maximum heart rate can be off by 10 or more beats. Medications, heat, sleep, caffeine and stress change heart rates. Some conditions need medical guidance before exercise. This page is educational, not medical advice. Anyone with a heart condition, symptoms during exercise or concerns about starting a program should consult a clinician first.
Quick answers
What people ask about heart-rate reserve
Is 220 minus age accurate? It is a rough average with wide individual variation, often off by ten beats or more. A supervised test gives a better maximum. Do not treat the formula as a limit.
Why use reserve instead of a plain percentage of maximum? Because resting rate reflects fitness. Scaling within the reserve gives fitter people a more suitable target than the same percentage of maximum.
Put it to work
How heart-rate reserve is calculated
At the target heart rate calculator’s worked-example inputs, target heart rate is 149, estimated maximum heart rate is 185. Moving age from 17.0 years to 53.0 years moves that first figure from 136.4 to 161.6.
Open the Target Heart Rate Calculator →
These are training estimates, not medical clearance. Heart rate, pace and strength benchmarks vary with fitness level, health conditions and medication. Consult a physician before starting a new exercise program, especially with an existing heart or health condition.
Keep reading
Nearby in the glossary
- ← Gross revenue retention (GRR)
- Heat index →
- All 174 defined termsThe complete Free Calculators Online financial glossary.