Target Heart Rate Calculator: Find Your Training Zones

You need two numbers: your age and your resting heart rate. The resting value is the one people usually guess — do not guess it, because every zone target shifts with it.

Step by step

1. Measure your resting heart rate. Sit quietly for five minutes, then count your pulse for 60 seconds — or take it first thing in the morning before getting up. Repeat on two or three mornings and use the average.
2. Enter your age and resting heart rate. Age estimates your maximum; resting heart rate personalises the zones.
3. Press Calculate. You get your maximum heart rate, five Karvonen zones and the simple percentage zones.
4. Pick the zone that matches your goal. Zone 2 for easy aerobic base, zone 3 for steady cardio, zone 4 for hard intervals — see the zone guide below.

Why resting heart rate matters

A lower resting heart rate usually means a fitter heart, and the Karvonen method rewards it with higher targets. In the example above, dropping resting heart rate from 70 to 60 raises the 70% target from 144 to 151 bpm. As your fitness improves, re-measure and recalculate — your zones should move with you.

Each zone trains a different energy system. Most of your weekly training — for general fitness, roughly four out of five sessions — belongs in the easy zones, with only short efforts in the hard ones. The American Heart Association's guide to target heart rates explains the same zone logic for everyday exercisers.

Zone (Karvonen)	Intensity	Feels like	Good for
Zone 1	50–60%	Very easy, could talk freely	Warm-ups, recovery, beginners
Zone 2	60–70%	Easy, steady breathing	Aerobic base, fat metabolism, long sessions
Zone 3	70–80%	Moderate, talking in phrases	Cardio fitness, tempo efforts
Zone 4	80–90%	Hard, short sentences only	Speed, intervals, race pace
Zone 5	90–100%	Maximum, cannot talk	Short sprints, experienced athletes

Karvonen or simple percentages?

Use Karvonen when you know your resting heart rate — it is the more personal answer. Use simple percentages for a quick check mid-workout, since they need only your age. The calculator shows both so you can compare; expect Karvonen targets to run a little higher for fit people and a little lower for beginners.

The 220-minus-age estimate is a population average, not a personal measurement. Individual maximums commonly differ by 10 to 15 beats either way, and some people fall further outside. Treat your zones as starting points and adjust by feel: if zone 2 feels hard, your true maximum is probably lower than estimated.

When to get a real measurement

If you train seriously, a graded exercise test or a hard field test (a well-rested, all-out 3-minute effort after a thorough warm-up) gives a truer maximum than any formula. Athletes on heart medication should ask their doctor first — beta blockers, for example, lower heart rate and make these zones unreliable.

Pair zones with fuel

Harder zones burn more energy per minute, so zone-based training works best alongside an eating plan. Once you know your typical training mix, a calorie calculator can estimate your daily needs including exercise, so your harder weeks are properly fuelled rather than accidentally under-eaten.

Zones only work if your heart rate reading is trustworthy. Wrist sensors are fine for steady efforts but lag during intervals; a chest strap is more accurate when the pace changes quickly. Take readings in similar conditions — heat, dehydration and caffeine all push heart rate up for the same effort.

Situation	What to do
First 2–3 weeks	Stay in zones 1–2 to build base fitness safely
Hot weather	Expect 5–10 bpm higher; judge by effort too
Illness or poor sleep	Train easy or rest — resting HR will be elevated
Intervals day	Warm up 10 minutes, then use zones 4–5 for short reps
Long slow session	Cap yourself at the top of zone 2, even if it feels too easy

Do not forget hydration

Dehydration raises heart rate for a given pace, which can push you into a higher zone than your effort deserves — a phenomenon runners call cardiac drift. Drinking to a plan keeps the numbers honest, and a water intake calculator gives you a daily baseline to adjust for training days.