Heart‑rate zones.

How to use your zones

Enter your age (and resting HR if using HRR) to get zone ranges. Use Zone 2 for easy aerobic base, Zone 3 for sustained tempo, Zone 4 near lactate threshold, and Zone 5 for short VO₂ intervals. Mix zones across the week and recover well.

How the heart-rate formulas compare

The calculator estimates your training zones by pairing a maximum heart-rate model with either a straight percentage (Max%) or the Karvonen Heart-Rate Reserve method. If you provide a measured max HR the formulas adapt automatically.

Max HR estimation

Formula	Expression	Pluses	Minuses
Tanaka et al.	Max HR = 208 − 0.7 × age	Validated on a large mixed-age cohort; slightly lower error for masters athletes.	Still an average — individual variation ±10–15 bpm is common.
Fox "220 − age"	Max HR = 220 − age	Easy to remember, historically widespread in fitness materials.	Overestimates for older adults and underestimates for younger runners more often than Tanaka.
Custom	Max HR = your lab/field-tested value	Removes model error when you know your true maximum.	Requires an all-out test; risky without supervision and can change with detraining.

Zone calculation methods

Method	Core formula	When it shines	Watch-outs
Max%	Zone range = Max HR × target %	Simple group coaching, when resting HR is typical (≈60–70 bpm) and you just need quick zones.	Ignores individual differences in resting HR; athletes with very low resting HRs can get ranges that feel too easy.
Karvonen (HRR)	Target HR = Resting HR + (Max − Resting) × %	When you track resting HR and want zones that scale to your aerobic fitness and recovery status.	Requires reliable resting HR data and shifts if you’re fatigued or ill.

Regardless of method, zone boundaries are rounded to whole beats. Check perceived effort and pace against these numbers—especially in heat, humidity, or on hills—to ensure the training effect matches your plan.

Training strategies for each heart-rate zone

Heart-rate training works best when you define the purpose of every run. Use Zone 1 (50–60% Max) for active recovery walks, short jogs after tough workouts, and morning shakeouts. Zone 2 (60–70%) is the aerobic base builder—spend the bulk of your weekly mileage here to increase mitochondrial density, fat utilisation, and running economy. Zone 3 (70–80%) targets lactate threshold; slot it into tempo runs, steady long-run finishes, or fartlek segments so you can hold a strong pace without tipping over into anaerobic distress.

Zone 4 (80–90%) should be used sparingly for cruise intervals or hilly surges. Limit continuous time at this intensity to 20 minutes and always sandwich the work with easy running. Zone 5 (90–100%) is your top gear: deploy it for strides, hill sprints, or short track intervals that emphasise power and VO₂ max. To stay healthy, avoid stacking Zone 4 and Zone 5 sessions on consecutive days—alternate hard days with easy or cross-training days.

Combine heart-rate cues with breathing rhythm (nasal vs mouth) and Rate of Perceived Exertion (RPE). If your heart rate is slow to rise but breathing feels ragged, it may signal accumulated fatigue or dehydration. Conversely, if heart rate spikes unexpectedly during an easy run, heat or caffeine could be the culprit; slow down, hydrate, or postpone the workout.

Pacing and workout ideas by zone

The table pairs each zone with typical RPE cues, suggested running paces relative to race efforts, and example workouts. Use it to translate the calculator output into the day-to-day structure of your plan.

Adjust paces for terrain and weather; keep recoveries truly easy so your heart rate drops before the next repetition.

Zone	RPE	Pace reference	Example workouts
1	1–2 / very easy	90–120 seconds slower than marathon pace	30–45 min recovery jog, 20 min mobility walk + strides
2	3–4 / comfortable	60–90 seconds slower than marathon pace	60–90 min long run, double run shakeouts, aerobic build weeks
3	5–6 / steady	Half-marathon pace ±10 sec	3×10 min tempo with 2 min jog, 45 min steady-state progression
4	7–8 / hard	10K pace ±5 sec	5×1 mile at threshold with 2 min jog, hill repeats of 6×3 min
5	9–10 / very hard	3K–5K pace or faster	10×400 m with 200 m jog, 8×30 sec hill sprints with full walk-down

Keep the total time at Zone 5 below 12–15 minutes per session and ensure Zone 4 plus Zone 5 volume stays under 20% of weekly mileage. As you progress, extend Zone 3 segments or add gentle surges late in long runs, but guard your recovery—sleep, nutrition, and mobility work keep heart-rate responsiveness high.

Sample week using calculated zones

Here is how a balanced seven-day schedule could look for an intermediate runner targeting a half marathon. Adjust volume to match your experience and the resting HR trends you track in the calculator.

Sample assumes a long-run focus with two quality sessions; swap days to fit your personal rhythm.

Day	Session focus	Primary zones	Notes
Monday	45 min recovery jog + mobility	Zone 1–2	Keep heart rate low; include light strides if legs feel heavy.
Tuesday	Tempo intervals (3×12 min)	Zone 3–4	Use Karvonen zones if you track resting HR; cool down at Zone 1.
Wednesday	Cross-training or easy spin	Zone 1–2	Observe how heart rate responds to non-running stimulus.
Thursday	VO₂ max session (8×400 m)	Zone 5	Walk or jog between reps until HR drops to Zone 2 before starting the next.
Friday	Easy run 50 min	Zone 2	Monitor cardiac drift; cut short if HR climbs despite steady pace.
Saturday	Long run with final 20 min steady	Zone 2 progressing to Zone 3	Check HR every kilometre; fuel early to hold steady effort.
Sunday	Rest or yoga	Zone 1 / Off	Track morning resting HR to confirm you are ready for the next week.

Repeating a structure like this for 3–4 weeks lets you compare resting HR, heart-rate recovery after workouts, and zone drift during long runs. Adjust the intensity knobs if signs of overreaching appear—elevated resting HR, suppressed appetite, or stubborn fatigue.

Example use cases

The calculator supports more than day-to-day workouts. Use the scenarios below to see how heart-rate insight can steer bigger decisions.

1. Returning from injury: Start with Zone 1–2 run-walk sessions and ensure heart rate stays at the lower end of the range. Gradually add longer Zone 2 stretches once recovery heart rate drops quickly after each walk break.
2. Marathon build: Map long-run segments to the Zone 2 midpoint and practise finishing the last 20–30 minutes in Zone 3. This approach engrains even pacing and teaches you to fuel before cardiac drift ramps up.
3. Heat acclimation: During hot weeks, cap your sessions at the top of each zone rather than chasing pace. Track the point where your heart rate climbs—acclimation is working when the drift occurs later in the run.
4. Masters training: Use Karvonen zones to account for lower resting HR. If overnight resting HR rises, trim Zone 4–5 sessions and add strides within Zone 2 runs until trends normalise.

Jot quick notes after every run about terrain, temperature, and stress. Patterns emerge quickly, showing whether lifestyle adjustments or training tweaks keep your heart-rate responses aligned with goals.

Heart-rate training FAQs

Tap the accordions to get answers on calibration, accuracy, and how to blend heart-rate data with pace.