Heart Rate Zone Calculator

What this heart rate zone calculator does

It works out your five training heart-rate zones — warm up, fat burn, aerobic, threshold, and maximum — from your age or your actual max heart rate. Add your resting heart rate and it switches to the Karvonen (heart rate reserve) method, which accounts for your individual fitness level instead of just a flat percentage of your max, giving noticeably more personalized zones.

Who it's for

Runners, cyclists, and anyone training with a heart rate monitor who wants to train in the right zone for the workout they're doing — easy recovery runs in Zone 2, interval work in Zone 4, without having to do the percentage math by hand every time.

How to use it

• Enter your age, and pick a max heart rate formula: the classic 220 minus age, the more accurate Tanaka formula, or enter your actual tested max HR if you know it.
• Optionally add your resting heart rate (taken first thing in the morning before getting out of bed is most accurate) to switch to the Karvonen method.
• Your five zones update instantly, each shown as a BPM range with a short description of what that intensity should feel like.

Real-world use cases

• Structuring a training week: keep easy runs in Zone 2, save Zone 4–5 efforts for interval or tempo sessions instead of accidentally running every workout too hard.
• Setting up a heart rate monitor or smartwatch with custom zones instead of relying on the device's generic default ranges.
• Fat-burning vs. cardio training: Zone 2 is where the body draws more heavily on fat for fuel, which is why it's often the target zone for endurance base-building.
• Checking recovery: a resting heart rate that's creeping up day to day can be an early sign of overtraining or illness — worth tracking alongside your zones.

Frequently asked questions

What's the difference between the 220-minus-age formula and Tanaka?

220 minus age is the classic estimate but tends to be less accurate, especially for older adults. The Tanaka formula (208 − 0.7 × age), based on a larger and more recent research pool, is generally considered a better estimate for most people.

What is the Karvonen method?

Instead of just taking a percentage of your max heart rate, Karvonen factors in your heart rate reserve (max HR minus resting HR), which better reflects your actual fitness level — two people with the same max HR but very different resting HR will get different, more personalized zones.

Which zone should I train in most?

Most endurance training plans recommend spending roughly 80% of training time in Zones 1–2 (easy, conversational effort) and the remaining 20% in Zones 4–5 (hard efforts), with Zone 3 used more sparingly — often called "polarized" training.

How do I measure my resting heart rate accurately?

Check it first thing in the morning before getting out of bed, ideally for a full 60 seconds, over a few days to get a reliable average — it fluctuates with sleep, stress, and hydration.

Is a heart rate monitor necessary to use these zones?

It helps for real-time feedback during a workout, but you can also use perceived effort as a rough guide — Zone 2 should feel like you could hold a conversation, Zone 4–5 should feel noticeably hard to speak through.