Heart rate zones for 25-year-olds
Estimated max HR of 191 bpm from the Tanaka formula, with all five zones as a percentage of it. Every boundary below is drawn as a band, because an age-predicted max carries a 7–11 bpm standard error and a zone is only about 19 bpm wide.
Estimated max HR
191 bpm
±10 typical individual spread
Zone 2 (aerobic base)
115–134 bpm
ceiling anywhere in 127–141
Zone 4 (threshold)
153–172 bpm
floor anywhere in 145–161
All five zones at age 25
- Z1RecoveryActive recovery and warm-up96–11550–60% HRmax
- Z2Aerobic BaseFat oxidation, mitochondrial density115–13460–70% HRmax
- Z3TempoMuscular endurance, lactate clearance134–15370–80% HRmax
- Z4ThresholdLactate threshold, race pace153–17280–90% HRmax
- Z5VO2 MaxPeak aerobic power, short intervals172–19190–100% HRmax
These edges are bands, not lines. Your zone 2 ceiling calculates to 134 bpm, but on an age-estimated max the honest margin is 127–141 bpm. Zone 2 is only 19 bpm wide, so that margin covers about 74% of the zone. That is the fade on the bars above. Enter a max HR you have actually seen and it disappears.
Against 220 − age
At 25, 220 − age reads 4 bpm high. It runs high for everyone under 40 and low for everyone over.
Both are population averages. Neither gap is bigger than the scatter between two people of the same age, which is the more interesting problem.
How to use these zones
For most endurance training, about 80% of weekly volume sits in zones 1–2 (below 134 bpm) and 20% in zones 4–5 (above 153 bpm). Zone 3 is the grey zone — too hard to recover from, too easy to drive peak adaptation. Minimise it unless you are doing deliberate tempo work.
That distribution assumes the boundaries are roughly right, which is the part an age formula cannot promise. Calibrate by feel: zone 2 conversational, zone 4 sustainable for 30–45 minutes at a hard effort, zone 5 finished inside five minutes. Where the numbers and the feel disagree, your real max HR differs from 191 bpm and the feel wins.
Replace the estimate
The full calculator takes a measured max HR — at which point the bands above collapse to lines — and adds the Karvonen method, which uses your resting heart rate, plus MAF 180.
Where the numbers come from
What an age formula can and cannot tell you
The estimated max HR here is 208 − 0.7 × age, from Tanaka, Monahan and Seals in the Journal of the American College of Cardiology, 2001. They pooled 351 published studies — 492 group means, 18,712 subjects — then measured max HR directly in 514 more adults to check the line held. It did, and it beats 220 − age, particularly for older adults. That is why this calculator uses it.
What it is not is a statement about you. The r = −0.90 that gets quoted alongside it is the fit to those 492 group averages. Average a few hundred 45-year-olds and you will land close to 177 bpm. One 45-year-old will not. Tanaka's paper publishes no individual-level standard error at all. The studies that do measure that scatter put it at 7–11 bpm for age-based prediction, with most univariate equations above 10 — Robergs and Landwehr, Journal of Exercise Physiology Online, 2002, reviewing two decades of the literature.
Ten beats is not a rounding error at this scale. Each zone spans a tenth of your max — around 18 bpm for most adults. So a boundary drawn from an age formula carries a margin of roughly ±7 bpm, most of a zone's width. Two people the same age can be a full zone apart at the same heart rate. That is why the bars on this page fade at their edges instead of ending in a crisp line: we would rather draw the band than print a number that looks measured when it is modelled.
Karvonen does not fix this
Heart rate reserve is the better method — two people with the same max but different resting rates should not get the same zones. But it adds a second input to get wrong, and a guessed resting HR propagates straight into every zone. Boundaries are rest + % × (max − rest), so a resting HR 10 bpm too high lifts your zone 1 floor by 5 bpm and your zone 2 ceiling by 3 — and it moves every zone the same direction, so nothing cancels. A number you half-remember, or one taken sitting at a desk, is not a resting heart rate. Take it before you get out of bed, five to seven mornings running, and average. A watch tracking you overnight will do this better than you will.
Two things collapse the band
The first is a max HR you have actually seen — the top of a hard hill-repeat session, a race finish, a supervised test. Enter that and the shading disappears, because the number is measured rather than modelled. The second is free: calibrate against how the effort feels. Where the numbers and the feel disagree, the feel is the measurement.
- Z1 Recovery — Easy enough to feel like you are not training
- Z2 Aerobic Base — Full sentences, no gasping
- Z3 Tempo — Short sentences; comfortably hard
- Z4 Threshold — Holds for 30–45 minutes and hurts
- Z5 VO2 Max — Over inside five minutes, one way or another
We have published no research of our own on heart-rate zones, so nothing on this page rests on our data — it rests on the two papers named above. How we handle that distinction generally is in our methodology, and the studies we have run are in the research library.
Frequently asked questions about HR zones at age 25
What is the average max heart rate for a 25-year-old?
Using Tanaka, Monahan and Seals (2001), 208 − 0.7 × age puts the average at about 191 bpm. The word doing the work there is "average" — that regression was fitted to 492 group means, not to individuals, and the studies that measure individual scatter put the standard error of age-based prediction at 7–11 bpm (Robergs & Landwehr, 2002). A real 25-year-old can easily sit ten beats either side of 191. Only a field test or lab measurement gives you your own number.
What should my zone 2 heart rate be at 25?
On the Tanaka estimate, zone 2 for a 25-year-old works out at roughly 115–134 bpm, or 60–70% of max HR. This is the aerobic-base range: you should be able to hold a conversation in full sentences. Treat the ceiling as a band rather than a line — with an estimated max, 134 bpm carries an honest margin of about 127–141 bpm, which is most of the width of the zone itself.
Is the 220 − age formula still used for 25-year-olds?
For a 25-year-old, 220 − age gives 195 bpm against Tanaka's 191 — 4 bpm high. The two cross at 40; below that the old formula always reads higher. But the gap between the two formulas is smaller than the gap between two people of the same age, so replacing one population average with a better population average only gets you so far.
How do I know if these zones are right for me?
You calibrate them against how training actually feels. Zone 2 should be conversational. Zone 4 should be sustainable for 30–45 minutes and should hurt. Zone 5 should be over inside five minutes. If the numbers and the feel disagree, your real max HR differs from the 191 bpm estimate — and the feel is the measurement. A max HR field test, or a watch that has genuinely seen you max out, replaces the estimate outright.
Do these zones work for cycling too?
Not directly. Max heart rate is mode-specific: cycling max HR typically comes in below running max HR for the same athlete, so zones calibrated for running read slightly high on the bike. These are running zones. For cycling, measure a cycling-specific max or work from power instead.
Zones for other ages
Read more
An age-based estimate is a starting point. The explainer and the research library cover what each zone trains and how far individual max HR really drifts from the formula.