What heart rate should I run at to burn fat?
Got a new watch or fitness band and suddenly everyone is talking about heart rate zones? It's simple: your heart has a max rate (the highest it can hit during effort) and a resting rate (when you're lying in bed in the morning). Between these two numbers there are 5 zones: and each one trains your body for a different thing.
Enter your age, optionally your resting heart rate (taken right after waking, lying down, the best moment) and you'll see 5 zones in bpm (beats per minute), ready to type into your watch.
Zone 2 (green) = the most-asked-about, that's where you burn fat during easy running or cycling. Zones 4-5 (orange-red) = short, intense intervals. Every zone has its purpose, the calculator shows all five, in your numbers.
How to use it
- Enter your age: that's enough for the calculator to estimate your max heart rate (the highest your heart can reach during effort).
- Optionally enter your resting heart rate (measured in the morning, lying down, right after waking: before coffee, before getting up). For an adult that's usually 60-80 bpm. With this number the calculator builds more accurate zones.
- Pick a formula for max heart rate: Tanaka (default, modern, good for most adults), Classic (220 minus age, easy to remember, but less accurate), Gulati (specifically for women), HUNT (for physically active people).
- Pick a method: % of max heart rate: simple approach, good to start. Karvonen: a more accurate formula (uses resting heart rate too). Karvonen shows more realistic zones if you're reasonably fit.
- Look at the colored bar: from blue (recovery) through green (fat burn) to red (max). The vertical line is your resting heart rate marked on the bar.
- The table below the bar shows each zone: bpm range (these numbers go into your watch), training purpose and how it feels (can you talk, are you gasping).
- The "how to spot the zone" section is a quick cheat sheet: if you can sing, you're in Z1. If you can hold a full conversation, you're in Z2. And so on. Works without looking at the watch.
When this is useful
Six typical situations where people check their heart rate zones:
- Setting up a new watch or heart rate strap: Garmin, Polar, Apple Watch, Fitbit, Whoop, every one of them asks for zones in bpm. Type your age in here → copy 5 numbers from our calculator. Done. No 40-page manual reading.
- Planning a cardio workout: you want to burn fat, not exhaust yourself for nothing. Fat burn is most efficient in Zone 2 (60-70% of max). The calculator shows you specific bpm: hold them for 30-60 minutes and you know you're doing it right.
- Checking if you're running in the right zone: the watch averaged 160 bpm. A lot or a little? Type your age in → 160 is Zone 4 (lactate threshold) for you. So you ran too hard for an easy day.
- Trainer or doctor asks about your zones: at a consultation the dietitian asks: *"which zone do you train in most?"*. Without a calculator you can't guess, with ours you give a concrete answer in 30 seconds.
- Programming HIIT intervals: typical pattern: 30 seconds in Z5 (max effort) + 90 seconds in Z2 (easy). The calculator gives you precise bpm for both zones.
- Coming back from a break / injury: the doctor says: *"don't go above 70% of max"*. What does that mean in bpm? For a 40-year-old that's roughly 125 bpm. You know where the ceiling is.