How do you calculate heart rate zones for cycling?
Every heart-rate zone system is a set of percentages hung from one anchor number, and the anchor is the whole argument. Three anchors are in common use: your lactate threshold heart rate (LTHR — roughly the heart rate you can hold for an hour flat out), your maximum heart rate, and your heart-rate reserve (max minus resting, the Karvonen method). Coaching systems built for cyclists — Coggan's levels and Joe Friel's zones — use LTHR, because it's the number a hard 30-minute ride will give you and because it tracks the steady efforts cycling is made of. Watches and head units default to percent of max, because they can estimate max from your age without asking you to do anything. The calculator offers all four so you can use the anchor you actually measured; the table further down shows why that choice matters more than the percentages do.
How do you find your lactate threshold heart rate (LTHR)?
Friel's field test is the standard: after a warm-up, ride 30 minutes as hard as you can sustain, alone, on a steady road or the trainer, and take the average heart rate of the last 20 minutes as your LTHR. Start the average at the 10-minute mark rather than the beginning because heart rate takes several minutes to catch up with a hard effort — including that lag would drag the number down. Pace it like a time trial, not a sprint that fades: if the last five minutes are slower than the first five, the average is a little high. Retest every couple of months in season; LTHR moves less than FTP does, but it moves.
Max heart rate is a ceiling that barely changes with training, that most riders never actually reach outside a race, and that age formulas guess with a ±10 bpm scatter. Threshold heart rate is a working number: it's where riding gets hard for you, it can be measured in half an hour, and it lines up with the FTP your power zones are built on. Two riders with the same max can have thresholds 15 bpm apart — which is why percent-of- max zones fit some riders well and others not at all.
Heart rate zones chart by LTHR
Coggan's five heart-rate levels at three common thresholds. Each zone starts one beat above the previous one's ceiling, so no heart rate falls between zones:
| Zone | % of LTHR | LTHR 150 | LTHR 165 | LTHR 180 |
|---|---|---|---|---|
| Z1 · Active Recovery | ≤68% | under 103 bpm | under 113 bpm | under 123 bpm |
| Z2 · Endurance | 69–83% | 103–125 bpm | 113–137 bpm | 123–149 bpm |
| Z3 · Tempo | 84–94% | 126–141 bpm | 138–155 bpm | 150–169 bpm |
| Z4 · Lactate Threshold | 95–105% | 142–158 bpm | 156–173 bpm | 170–189 bpm |
| Z5 · VO2max | over 105% | 159+ bpm | 174+ bpm | 190+ bpm |
Coggan's published percentages (Training and Racing with a Power Meter), rounded to whole beats by the same engine as the calculator. Coggan lists no heart-rate ranges for power levels 6 and 7 — efforts that short are over before heart rate responds.
Coggan's 5 zones vs Friel's 7 zones
Both hang from LTHR; they cut the top of the range differently. Friel keeps Zones 1–4 below threshold and splits everything above it into 5a, 5b and 5c, which suits riders who train intervals by heart rate. Coggan's Zone 4 straddles threshold (95–105% of LTHR) to match his power Level 4. For the 165-bpm rider:
| Coggan | bpm | Friel | bpm |
|---|---|---|---|
| Z1 · Active Recovery | under 113 | Z1 · Recovery (≤80%) | under 133 |
| Z2 · Endurance | 113–137 | Z2 · Aerobic (81–89%) | 133–147 |
| Z3 · Tempo | 138–155 | Z3 · Tempo (90–93%) | 148–153 |
| Z4 · Lactate Threshold | 156–173 | Z4 · Sub-Threshold (94–99%) | 154–163 |
| Z5 · VO2max | 174+ | Z5a · Super-Threshold (100–102%) | 164–168 |
| Z5b · Aerobic Capacity (103–106%) | 169–175 | ||
| Z5c · Anaerobic Capacity (over 106%) | 176+ |
Rows are position, not equivalence: Friel's Zone 2 (133–147) sits where Coggan's Zone 2 ends and Zone 3 begins. Same rider, same LTHR — different fences. Percentages from The Cyclist's Training Bible and Training and Racing with a Power Meter.
Heart rate zones from max heart rate — and why 220 − age is a guess
The five bands most devices ship with are 50–60, 60–70, 70–80, 80–90 and 90–100% of max heart rate. The formula they use to fill in the max is the problem. "220 − age" came from a 1971 survey of other studies, was never meant as a prediction for individuals, and the later regressions that replaced it (Tanaka's 208 − 0.7 × age is the best known) all found the same thing: real maxima scatter about 10 bpm either side of the line, one standard deviation. A third of riders sit outside even that.
| Age | 220 − age | 208 − 0.7 × age | Likely range (±10) |
|---|---|---|---|
| 25 | 195 bpm | 191 bpm | 181–201 bpm |
| 30 | 190 bpm | 187 bpm | 177–197 bpm |
| 35 | 185 bpm | 184 bpm | 174–194 bpm |
| 40 | 180 bpm | 180 bpm | 170–190 bpm |
| 45 | 175 bpm | 177 bpm | 167–187 bpm |
| 50 | 170 bpm | 173 bpm | 163–183 bpm |
| 55 | 165 bpm | 170 bpm | 160–180 bpm |
| 60 | 160 bpm | 166 bpm | 156–176 bpm |
| 65 | 155 bpm | 163 bpm | 153–173 bpm |
Fox et al. 1971 and Tanaka et al. 2001; the range is one standard deviation around Tanaka, per the Robergs & Landwehr review. If you want your real max, a hard 5-minute climb finished with an all-out minute, fresh, will get you within a few beats — the calculator lets you type either.
A 45-year-old's estimated max is 177 bpm, so their Zone 2 reads 107–124 bpm. But a real max anywhere from 167 to 187 is ordinary, which puts the top of Zone 2 anywhere from 117 to 131 bpm and the top of Zone 4 anywhere from 150 to 168 — a window 18 beats wide for the zone you'd do threshold intervals in. That's the uncertainty a percent-of-max chart hides, and it's why the calculator flags an estimated max instead of quietly using it.
Same rider, four methods: which Zone 2 is right?
Take one rider — threshold 165, max 185, resting 55 — and compute the endurance zone every way the sport does:
| Method | Anchor | Zone 2 (bpm) | Threshold zone (bpm) |
|---|---|---|---|
| Coggan · % of LTHR | LTHR 165 | 113–137 | 156–173 (Z4 Lactate Threshold) |
| Friel · % of LTHR | LTHR 165 | 133–147 | 154–163 (Z4 Sub-Threshold) |
| % of max HR | max 185 | 112–130 | 149–167 (Z4 Threshold) |
| Heart-rate reserve (Karvonen) | max 185, rest 55 | 134–146 | 160–172 (Z4 Threshold) |
All four computed by the calculator's engine for the same rider. The top of Zone 2 lands anywhere from 130 to 147 bpm — 17 beats apart — before any question of whether the rider had coffee.
None of them is "right"; fixed percentages can't locate any individual's threshold, which is why every method disagrees with every other. The useful conclusion is narrower: pick one anchor you measured, use one model, and stay consistent, so that "Zone 2" means the same thing in March and in September. If you measured LTHR, use an LTHR model — your zones then move when your fitness does. If all you have is a max, the reserve method beats plain percent-of-max for anyone with a low resting heart rate, because 55 bpm at rest means the bottom half of your range is empty and the flat percentages spend two zones in it.
Heart rate zones vs power zones
Coggan built his heart-rate levels to sit beside his power levels, one to one, which is what lets this page print both on one sheet. For a rider with an LTHR of 165 and an FTP of 245 W:
| Zone | Heart rate | Power |
|---|---|---|
| Z1 · Active Recovery | under 113 bpm | 0–135 W |
| Z2 · Endurance | 113–137 bpm | 136–184 W |
| Z3 · Tempo | 138–155 bpm | 185–221 W |
| Z4 · Lactate Threshold | 156–173 bpm | 222–257 W |
| Z5 · VO2max | 174+ bpm | 258–294 W |
Heart rate from this calculator, watts from the power zones calculator — the same engine and the same Coggan table. Power Levels 6 and 7 have no heart-rate equivalent.
Use them for what each is good at. Power answers instantly and doesn't care how hot it is; heart rate lags an effort by a minute or two, drifts upward over a long ride, and reads high on caffeine and low on fatigue. So: pace intervals shorter than about five minutes by power or feel — heart rate hasn't arrived yet — and let heart rate govern the long, steady rides where it's most honest. The two together tell you something neither does alone: a familiar power at an unusually high heart rate is the earliest warning you'll get of heat stress, illness or too little recovery.
Why is my heart rate higher (or lower) than usual today?
The number moves for reasons that have nothing to do with fitness, and reading it well means knowing which is which:
| What you see | Likely cause | What to do |
|---|---|---|
| HR climbs steadily through a long ride at the same power | Cardiac drift — heat, dehydration, fatigue | Normal. Judge easy days by power or feel late in the ride; drink and cool. |
| HR is 5–10 bpm high from the first minute, effort feels normal | Caffeine, poor sleep, stress, heat | Ride to feel or power; note it. One day is noise. |
| HR is high AND the usual power feels much harder than normal | Fatigue, incoming illness, under-fueling | Turn the ride into recovery. Two or three such days in a row is a rest signal. |
| HR is unusually low and you can’t push it up | Deep fatigue or overreaching; sometimes just cold legs | If it persists with heavy legs, back off for several days. |
| HR barely responds to a 3-minute interval | Heart rate lags effort by 1–2 minutes | Expected. Pace short intervals by power or feel; HR is for the long stuff. |
| HR jumps 40 bpm out of nowhere, then normalizes | Chest strap dropouts, static from a dry strap or jersey | Wet the strap contacts; check the battery. A wrist sensor spikes on rough roads. |
Cardiac drift — the slow rise in heart rate at constant power — is the reason a Zone 2 ride paced by heart rate gets slower in its last hour. Hold the power (or the feel) and let the beats climb.
Which zone should you ride in most?
The same answer as for power: most of it easy. The training distributions documented in endurance athletes put roughly four fifths of time in Zones 1–2, a slice around threshold and a small dose flat out — the power zones page works that split out for 5-, 8- and 12-hour weeks, and the hours transfer directly to heart-rate zones. The trap heart rate makes easier to fall into is the middle: a Zone 3 heart rate feels productive, produces a satisfying average, and is the intensity most riders drift up to when "easy" gets boring. If your rides all average the top of Zone 2 or above, the plan isn't polarized — it's stuck.
Training load without a power meter
Platforms estimate a heart-rate TSS (hrTSS) from time in your heart-rate zones, and it works reasonably for steady rides. It under-counts anything intervalish, because heart rate never reaches the zone the effort was in, and it inherits every error in the anchor — set your LTHR ten beats high and every ride scores low for months. The TSS calculator covers what the score means and how a weekly total turns into fitness; if you train by heart rate, treat hrTSS as consistent with itself rather than comparable with a friend's power-based number.