Target Heart Rate Calculator
Find your 5 training heart rate zones using the Karvonen method with resting heart rate.
Inputs
Measure upon waking, before getting out of bed, for 3 consecutive days and average.
Tanaka is more accurate above age 40; Fox overestimates MHR in older adults.
Maximum Heart Rate
185bpm
Heart Rate Reserve
120bpm
Zone 1 — Very Light
125bpm
50–60% HRR
Zone 2 — Light
137bpm
60–70% HRR
Zone 3 — Moderate
149bpm
70–80% HRR
Zone 4 — Hard
161bpm
80–90% HRR
Zone 5 — Maximum
173bpm
90–100% HRR
Step by step
Maximum heart rate
User-entered MHR
= 185 bpm
Heart rate reserve
185 − 65
= 120 bpm
Zone 3 example (Karvonen at 70%)
120 × 0.70 + 65
= 149 bpm
5-Zone training plan
| Zone | Name | Lower (bpm) | Upper (bpm) | Purpose |
|---|---|---|---|---|
| 1 | Very Light | 125 | 137 | Active recovery; warm-up and cool-down. |
| 2 | Light | 137 | 149 | Fat-burning base; comfortable talking pace. |
| 3 | Moderate | 149 | 161 | Aerobic endurance; slightly breathless. |
| 4 | Hard | 161 | 173 | Lactate threshold; hard to maintain conversation. |
| 5 | Maximum | 173 | 185 | VO2 max intervals; unsustainable beyond 2–3 minutes. |
How it works
The Karvonen method personalises training zones by factoring in your resting heart rate. A fitter person typically has a lower resting HR, which gives them a larger Heart Rate Reserve (HRR). Training at the same percentage of HRR therefore represents a higher absolute HR for the fit person — matching the actual physiological demand. The Tanaka formula for max HR is more accurate than the classic 220−age across ages 18–85, particularly for trained adults.
Formulas
Karvonen target heart rate
THR = (Max HR − Resting HR) × Intensity + Resting HR
- MHR
- Maximum heart rate (bpm)
- RHR
- Resting heart rate (bpm)
- I
- Training intensity as a decimal (e.g. 0.70 for 70%)
- THR
- Target heart rate (bpm)
Tanaka max HR
Max HR = 208 − 0.7 × Age
Heart rate zones are estimates. Maximum heart rate predictions carry ±10–12 bpm individual error. If you have a cardiovascular condition, consult your cardiologist before starting high-intensity exercise. Stop exercising and seek medical attention if you experience chest pain, dizziness or shortness of breath.
Frequently Asked Questions
How do I accurately measure my resting heart rate?
Measure immediately on waking, before getting out of bed, using a finger on your carotid or radial artery (or a wrist-based heart rate monitor). Count beats for 60 seconds. Average over 3 mornings. Stress, illness and alcohol elevate resting HR — measure on calm days.
What is the best zone for fat loss?
Zone 2 (60–70% HRR) uses the highest proportion of fat as fuel because intensity is low enough for oxidative metabolism. However, higher-intensity zones burn more total calories per session, which matters more than the fat-burning percentage. Both approaches work; the best zone is the one you'll sustain consistently.
Can I use this with a heart rate monitor?
Yes — set zone alarms on your device using the bpm ranges from this calculator. Most modern GPS watches allow custom zone setup. These zones are more accurate than device defaults, which typically use only age (220−age) without your resting HR.