Training · Physiology

Heart Rate Zone Calculator

Four ways to estimate your max HR, two ways to slice it into zones, and where your fat-burn and anaerobic thresholds land.

Measured first thing, lying down
Only affects the Gulati formula

Step 01

Pick Your Max Heart Rate

Click a row to select it — that formula becomes the max HR every zone and threshold below is built from. The spread between them is the point; fitness has no column here, because it barely changes your ceiling.

MethodFormulaYour HRmax

Step 02

Your Five Zones

% of Max is the simple default. Karvonen folds in your resting HR — which is where your fitness actually shows up — so for most people it's the better pick.

What each method does to the math — and which to use
% of Max HR Simplest

The math: multiplies your max HR by fixed percentages. Zone 2 is just 60–70% of max, full stop. Your resting HR never enters the calculation, so two people the same age with the same max get identical zones no matter how fit they are.

Trade-off: quick and universal (it's what most gym machines and apps default to), but it's blind to your individual fitness and the boundaries don't line up with any real physiological event.

Best when: you only know your max, and you want a fast ballpark map.

Karvonen / Heart Rate Reserve

The math: works off your reserve (max − resting), then adds resting back: resting + % × (max − resting). Because it folds in resting HR, it personalizes to you — and since resting HR drops as you get fitter, your zones shift up on their own over time.

Watch for: the same percentage lands higher here than in % of Max (you're adding resting HR back in), so Karvonen "Zone 2" is meaningfully harder than gym-machine "Zone 2." It also needs an accurately measured resting HR to be worth anything.

Best when: you have a reliable resting HR and want zones that track your fitness.

Quick pick: if you're not sure, use Karvonen — it costs you nothing extra (you've already entered your resting HR) and it reflects your fitness. Reach for % of Max only when you want the quick, universal number that matches gym machines and most apps.
One trap: "Zone 2" is not the same bpm in the two methods — Karvonen's runs higher. Pick one and stay in it; don't chase a Karvonen number during a %-of-max workout.

Built on your selected Tanaka max-HR estimate of bpm. Change it by clicking a different row in Step 01.

Zone%Heart Rate (bpm)Feels like

Step 03

Your Two Thresholds

These aren't a separate calculation — they're simply the top of Zone 2 and the top of Zone 4 from the table above, named. They always match whichever method you've selected, so follow the table for training and read these as what those boundaries mean.

Aerobic threshold (LT1 / VT1) — ceiling of the "fat-burning" zone, top of easy Zone 2. Below it you're fat-dominant and conversational.
Anaerobic threshold (LT2 / VT2) — where the system "goes anaerobic," top of Zone 4. Lactate now piles up faster than you clear it.
Fuel mix across intensity
Fat Carbohydrate
In % of Max these two lines are fixed fractions of your max; in Karvonen they already reflect your fitness through your resting HR. Either way they're estimates — the honest fix for real precision is a measured threshold test, since the formula spread alone can be 15+ bpm.

Estimates only — formula error (±7–12 bpm) is real, and beta-blockers, anemia, or recent surgery break these formulas entirely. A field or lab test beats any equation; confirm with your cardiologist before training hard off these numbers.