Training Zones Calculator

Training zones are defined intensity ranges that help athletes structure workouts with precision. Rather than training by feel alone, zones give you objective targets based on measurable physiological markers — your maximum heart rate, lactate threshold heart rate, functional threshold power, or threshold running pace. Each zone places a specific demand on your cardiovascular system and energy pathways, producing different training adaptations over time.

The core idea is simple: low-intensity work in zones 1 and 2 builds your aerobic foundation and fat-burning capacity while minimizing fatigue. Moderate efforts in zone 3 develop sustainable speed. High-intensity zones 4 and 5 push your lactate threshold and VO2 max higher. Spending the right proportion of time in each zone — guided by a periodized training plan — drives fitness gains far more efficiently than constantly training at the same moderate effort.

This training zones calculator supports three independent zone systems so you can work with whichever metric you track. The heart rate mode offers both the classic 5-zone Karvonen method (using your heart rate reserve) and the 7-zone LTHR method popularized for endurance sport. The power mode uses the Coggan FTP-based 7-zone framework standard in cycling. The pace mode derives 6 running pace zones from your threshold pace. All three systems share the same physiological philosophy — train at the right intensity, at the right time, for the right adaptation.

The Karvonen method, developed by Finnish physiologist Martti Karvonen in the 1950s, calculates training zones using Heart Rate Reserve (HRR) rather than raw percentages of max HR. This approach accounts for your resting heart rate, making zones individually calibrated even when two athletes share the same maximum heart rate.

Heart Rate Reserve is simply the difference between your maximum heart rate and your resting heart rate. A trained athlete with a resting HR of 45 bpm and a max HR of 190 bpm has an HRR of 145 bpm — a much wider working range than a sedentary person with the same max HR but a resting HR of 75 bpm. The Karvonen formula adds the appropriate fraction of that reserve back onto the resting heart rate to find each zone boundary.

The five zones produced are: Zone 1 Recovery (50–60% HRR), Zone 2 Aerobic (60–70% HRR), Zone 3 Tempo (70–80% HRR), Zone 4 Threshold (80–90% HRR), and Zone 5 VO2max (90–100% HRR). Well-trained endurance athletes should spend roughly 80% of their weekly training volume in zones 1–2 and the remaining 20% in zones 3–5, a distribution often called polarized training.

The 7-zone LTHR (Lactate Threshold Heart Rate) system anchors all zone boundaries to the heart rate at your lactate threshold — the intensity at which blood lactate begins to accumulate faster than it can be cleared. LTHR can be estimated from a 30-minute all-out time trial by averaging your heart rate over the final 20 minutes. Unlike the Karvonen method, LTHR zones do not use resting heart rate at all; every boundary is a fixed percentage of LTHR.

The seven zones are: Zone 1 Active Recovery (65–81% of LTHR), Zone 2 Endurance (81–89%), Zone 3 Tempo (89–93%), Zone 4 Sub-Threshold (93–99%), Zone 5a Super-Threshold (99–102%), Zone 5b Aerobic Capacity (102–106%), and Zone 5c Anaerobic (above 106%). Zones 5a, 5b, and 5c are split because high-intensity efforts carry meaningfully different physiological stresses and should be programmed separately in a training block.

This framework is widely used by triathlon and running coaches who favor LTHR over max HR because LTHR is more reproducible across the season and responds predictably to fitness changes. As your fitness improves and LTHR rises, all zone boundaries shift upward automatically — making it a self-calibrating system for long-term training.

Power training zones for cyclists are based on Functional Threshold Power (FTP): the highest average wattage you can sustain for approximately one hour. The 7-zone system developed by Andrew Coggan and Hunter Allen, detailed in Training and Racing with a Power Meter, divides effort from gentle recovery all the way to maximal neuromuscular sprints.

Because a power meter reports effort in real time without the cardiac lag that affects heart rate readings, power zones are the most precise tool for interval training. A 4-minute VO2max interval at zone 5 (105–120% of FTP) will hit the right physiological target whether you are fresh on Monday or fatigued on Friday — something heart rate cannot guarantee due to cardiac drift.

The seven Coggan power zones are: Zone 1 Active Recovery (below 55% FTP), Zone 2 Endurance (55–75% FTP), Zone 3 Tempo (75–90% FTP), Zone 4 Threshold (90–105% FTP), Zone 5 VO2max (105–120% FTP), Zone 6 Anaerobic Capacity (120–150% FTP), and Zone 7 Neuromuscular Power (above 150% FTP). FTP is most accurately established through a dedicated 20-minute test at maximum sustainable effort, then multiplying average power by 0.95 to approximate the true 1-hour value. Alternatively, an 8-minute all-out test × 0.90 provides a reasonable estimate.

Running pace zones are expressed in minutes and seconds per kilometre (or per mile) and are derived from your threshold pace — the pace you could sustain in a flat, all-out one-hour race. The calculator converts your threshold pace to total seconds per kilometre, multiplies by zone-specific intensity factors, then formats the result back into mm:ss notation.

Slower pace numbers mean easier effort in running, so zone boundaries are displayed with the slower (higher) value on the left and the faster (lower) value on the right. Zone 1 Easy/Recovery runs at 125–135% of threshold time per km (meaning 25–35% slower than threshold pace). Zone 2 Aerobic/Long run falls between 115–125%. Zone 3 Tempo sits at 105–115%. Zone 4 Threshold is right around race pace at 97–105%. Zone 5 VO2max intervals push to 90–97%, and Zone 6 Speed/Repetition efforts reach 80–90% of threshold time — your fastest controlled running.

Pace zones are particularly useful for athletes who train on roads or tracks without a heart rate monitor and prefer to set their GPS watch to a target pace range. They work well in stable conditions but should be adjusted upward on hot days, in wind, or on hilly terrain where external resistance inflates the physiological cost beyond what the pace number suggests. Combining pace zones with perceived exertion gives the most robust real-world guidance.

Knowing your zones is only half the work — structuring your weekly training around them is what drives adaptation. The most evidence-backed distribution for endurance athletes is the 80/20 polarized model: roughly 80% of session time in zones 1–2 and 20% in zones 4–5, with minimal time in the moderate zone 3. Research from Stephen Seiler and others shows that world-class endurance athletes across rowing, cycling, running, and cross-country skiing naturally converge on this split when training loads are analyzed.

To put this into practice: your easy runs, long rides, and recovery sessions should all stay firmly in zone 1–2. Reserve zone 4 threshold intervals and zone 5 VO2max efforts for designated hard workout days, separated by adequate recovery. Zone 3 tempo work has its place — especially for time-crunched athletes — but should not dominate your schedule, as sustained moderate effort accumulates fatigue without delivering the same aerobic ceiling gains as polarized training.

Re-test your key metrics every 4–8 weeks. Max HR is relatively stable, but LTHR, FTP, and threshold pace all improve with training. Updating your zones after a fitness block ensures your easy days stay truly easy and your hard days stay hard enough to produce adaptation. Athletes who fail to update zones often find their zone 2 rides drifting into zone 3 territory over time — a creep that compromises recovery and blunts performance gains.