Heart Rate Zone Calculator
Calculate your personalised heart rate training zones using the Karvonen formula, the most accurate method for runners. This calculator uses your resting heart rate and maximum heart rate to determine five distinct training zones — from easy recovery to all-out effort. You can also compare results from three different calculation methods. Pair your zones with a free personalised training plan to train smarter and run faster.
What Are Heart Rate Training Zones?
Heart rate training zones are ranges of heart rates that correspond to different exercise intensities. Each zone targets specific physiological adaptations — from fat burning and aerobic base building to lactate threshold improvement and maximal oxygen uptake. By training in the correct zone, runners can ensure every session has a purpose: easy days stay easy, hard days go hard enough, and recovery happens when it should.
Most coaches and sports scientists divide training into five heart rate zones, each representing a percentage range of your maximum heart rate or heart rate reserve. The boundaries differ slightly depending on which formula you use, which is why this calculator offers three zone-calculation methods for comparison.
How the Karvonen Formula Works
The Karvonen formula (also called the Heart Rate Reserve method) is widely regarded as the most accurate way to calculate personalised training zones. Developed by Finnish physiologist Dr. Martti Karvonen, it accounts for your individual fitness level by factoring in your resting heart rate — something simpler methods ignore.
The difference between your maximum and resting heart rate is called your Heart Rate Reserve (HRR). A fitter runner typically has a lower resting heart rate and therefore a larger reserve — which shifts their zones upward compared to a less fit runner of the same age. This is why the Karvonen method produces more accurate zones than a simple percentage of maximum heart rate.
Heart Rate Zone Breakdown
Zone 1 — Recovery (50–60%)
Very light effort. Used for warm-ups, cool-downs, and active recovery days. You should be able to hold a full conversation comfortably. This zone promotes blood flow for muscle repair without adding training stress.
Zone 2 — Aerobic / Endurance (60–70%)
The foundation of distance running. Most of your weekly mileage should be here. Builds aerobic capacity, improves fat utilisation, and strengthens the cardiovascular system. Conversational pace — if you can't chat, you're going too hard.
Zone 3 — Tempo (70–80%)
Comfortably hard. Tempo runs and marathon-pace efforts live here. Improves running economy, lactate clearance, and muscular endurance. You can speak in short sentences but not hold a full conversation.
Zone 4 — Threshold (80–90%)
Hard effort at or near your lactate threshold. Interval training, hill repeats, and 10K-pace runs. Dramatically improves your ability to sustain faster speeds. Speaking is limited to a few words at a time.
Zone 5 — Maximum (90–100%)
All-out effort. Short intervals, sprints, and race finishes. Develops VO2 max and neuromuscular power. Unsustainable for more than a few minutes. Used sparingly in training to peak performance.
Three Methods to Calculate Your Zones
| Zone Method | Formula | Needs RHR? | Accuracy |
|---|---|---|---|
| Karvonen | Target HR = (HRR × %Intensity) + RHR | Yes | Most accurate for individuals |
| % Max HR | Target HR = Max HR × %Intensity | No | Good general estimate |
| Zoladz | Target HR = Max HR − Zone Adjuster (bpm) | No | Simple subtraction method |
The Karvonen method is recommended because it accounts for your current fitness level through resting heart rate. The %MHR method is the simplest and works well if you know your actual max HR. The Zoladz method subtracts fixed values from your Max HR, producing slightly different zone boundaries that some coaches prefer.
All three methods require your maximum heart rate as input. If you don't know yours, the calculator estimates it using the Tanaka formula (208 − 0.7 × age), the Fox formula (220 − age), or the Gulati formula (206 − 0.88 × age, better for women) — you can choose which estimation formula to use. However, these are population averages and a lab-based VO2 max test or supervised field test will always give more precise results than any formula.
How to Measure Your Resting Heart Rate
- Measure in the morning — Take your pulse immediately after waking, while still lying in bed, before any caffeine or activity.
- Use a consistent method — Place two fingers on your wrist (radial artery) or neck (carotid artery) and count beats for a full 60 seconds. Alternatively, use a chest strap or smartwatch.
- Average multiple days — Record your resting heart rate for 3–5 consecutive mornings and take the average. Single-day readings can be affected by stress, poor sleep, or illness.
- Retest regularly — As your fitness improves, your resting heart rate will decrease. Retest every 4–6 weeks or after a significant training block.
How to Find Your Maximum Heart Rate
The most reliable method is a graded exercise test supervised by a sports medicine professional. However, you can also estimate it from age-based formulas or perform a field test:
| Method | Formula / Protocol | Accuracy |
|---|---|---|
| Tanaka formula | 208 − (0.7 × age) | ±7 bpm (population average) |
| Fox formula (classic) | 220 − age | ±10–12 bpm (less reliable) |
| Gulati (women) | 206 − (0.88 × age) | Better for female athletes |
| Field test | 3 × 3 min all-out hill repeats, record peak HR on third repeat | ±2–3 bpm (if performed correctly) |
| Lab test (VO2 max test) | Graded treadmill or cycling protocol to exhaustion | Gold standard |
Age-based formulas give population averages — individual Max HR can vary by 10–20 bpm in either direction. If heart rate training is central to your programme, a field test or lab test is worth the effort.
Typical Resting Heart Rate by Fitness Level
| Fitness Level | Resting HR (bpm) | Description |
|---|---|---|
| Sedentary | 70–80 | Little regular exercise |
| Moderately Active | 60–70 | Exercises 2–3 times per week |
| Very Active | 50–60 | Runs or trains 4–6 times per week |
| Elite Athlete | 35–50 | High-volume endurance training |
Why Heart Rate Training Works for Runners
Running by heart rate rather than pace alone ensures you're training the right energy system on any given day. It automatically adjusts for variables that affect performance: heat, fatigue, altitude, illness, and stress all increase heart rate at the same pace — your zones catch that shift and keep you honest.
The 80/20 rule — roughly 80% of your training in Zones 1–2 and 20% in Zones 3–5 — is backed by decades of research on elite endurance athletes. Most recreational runners make the mistake of running too hard on easy days and too easy on hard days, ending up stuck in a "grey zone" (Zone 3) that delivers diminishing returns. A heart rate monitor is the simplest tool to fix this.
Ready to Train Smarter?
Get a free personalised running plan that uses heart rate zones to structure your training. Choose your goal distance — from 5K to marathon — and let our generator build a plan that balances easy aerobic work with targeted hard sessions.
Generate Your Free Training PlanHow to Use Your Heart Rate Zones
- Easy runs (Zone 1–2) — These should make up 70–80% of your weekly mileage. They build your aerobic engine without excessive fatigue. If it feels too slow, it's probably about right.
- Tempo runs (Zone 3) — Sustained efforts at "comfortably hard" intensity. Typically 20–40 minutes at marathon to half-marathon effort. Builds lactate clearance ability.
- Interval training (Zone 4) — Repeated hard efforts of 2–6 minutes with recovery between reps. Pushes your lactate threshold higher, allowing you to sustain faster paces.
- Sprint / VO2 max work (Zone 5) — Short, all-out bursts of 30 seconds to 3 minutes. Used sparingly (once per week at most) to develop top-end speed and VO2 max.
- Recovery days (Zone 1) — After hard sessions or races, keep heart rate firmly in Zone 1. These runs promote recovery without adding training load.
Frequently Asked Questions
What is the Karvonen formula and how does it calculate heart rate zones?
The Karvonen formula calculates target heart rate zones using your Heart Rate Reserve (HRR) — the difference between your maximum heart rate and resting heart rate. The formula is: Target HR = ((Max HR − Resting HR) × %Intensity) + Resting HR. This method is more accurate than using simple percentages of maximum heart rate because it accounts for your individual fitness level through your resting heart rate. A fitter runner with a lower resting heart rate will get different (and more appropriate) zone boundaries than a less fit runner of the same age.
How do I find my maximum heart rate and resting heart rate?
For maximum heart rate, the most reliable method is a supervised graded exercise test, though the Tanaka formula (208 − 0.7 × age) provides a reasonable estimate. A field test — three hard 3-minute hill repeats, recording the peak HR on the final repeat — can also give an accurate reading. For resting heart rate, measure first thing in the morning while still in bed, before any caffeine or activity. Count beats for a full 60 seconds (or use a wearable), repeat over 3–5 mornings, and take the average.
What are the five heart rate zones and what are they used for?
The five zones are: Zone 1 (Recovery, 50–60%) for easy recovery and warm-ups; Zone 2 (Aerobic, 60–70%) for building your aerobic base — most of your running should be here; Zone 3 (Tempo, 70–80%) for marathon-pace and tempo efforts; Zone 4 (Threshold, 80–90%) for interval training and lactate threshold work; and Zone 5 (Maximum, 90–100%) for short sprints and VO2 max intervals. Each zone targets different energy systems and physiological adaptations.
Which heart rate zone calculation method should I use?
The Karvonen (Heart Rate Reserve) method is recommended for most runners because it accounts for your individual fitness level through your resting heart rate. If you don't know your resting heart rate, the %Max HR method is a simpler alternative that still gives useful zones. The Zoladz method uses fixed subtraction values and can work well for athletes who prefer a straightforward approach. For the most precise zones of all, a lab-based VO2 max test will give you exact Max HR and individualised training thresholds that no formula can match.
Can I use estimated heart rate values instead of measured ones?
Yes, but measured values are always more accurate. Age-based Max HR formulas have a standard deviation of ±7–12 bpm, meaning your actual Max HR could be significantly higher or lower than the estimate. If you rely on estimates, treat your zones as approximate guides rather than strict boundaries. For resting heart rate, the calculator provides activity-level estimates (sedentary ~70 bpm, moderately active ~60 bpm, very active ~50 bpm, elite ~40 bpm), but spending a few mornings measuring your actual RHR will dramatically improve zone accuracy.
How often should I update my heart rate zones?
Recalculate your zones every 4–6 weeks or after significant training blocks, race seasons, or extended breaks. As your cardiovascular fitness improves, your resting heart rate will typically decrease, shifting your Karvonen zones. Maximum heart rate decreases very gradually with age (roughly 0.7 bpm per year), so annual adjustments are sufficient for the Max HR component. If you notice your easy runs feel unusually hard or your zones no longer match your perceived effort, it's time to retest.
Why is 220 minus age not accurate for maximum heart rate?
The "220 − age" formula (Fox formula, 1971) was never intended as a precise prediction — it was derived from observational data with wide scatter. Research has shown it overestimates Max HR in younger adults and underestimates it in older adults. The Tanaka formula (208 − 0.7 × age), published in 2001 based on a meta-analysis of 351 studies, provides a more accurate population estimate. However, all age-based formulas have inherent limitations because individual Max HR varies significantly due to genetics, training status, and other factors.
What percentage of my training should be in Zone 2?
Research on elite endurance athletes consistently shows that approximately 80% of training volume should be at low intensity (Zones 1–2), with the remaining 20% at moderate to high intensity (Zones 3–5). This "polarised training" approach builds a massive aerobic engine while allowing adequate recovery. Most recreational runners run too fast on easy days, accumulating fatigue without the aerobic benefits. If you're training for a half marathon or marathon, Zone 2 running should be the backbone of your programme.