Zone 2 Heart Rate Calculator

Enter your resting heart rate and your maximum (or let the calculator estimate it from your age) to get your zone 2 band with the Karvonen method. Everything runs in your browser.

Your numbers
The Karvonen method needs your resting rate and your maximum heart rate.

Count your pulse for a full minute right after waking, before coffee.

Zone 2 range
Using a maximum of 184 bpm and a resting rate of 60 bpm.

134 to 147 bpm

Lower edge (60% of reserve)
134 bpm
Upper edge (70% of reserve)
147 bpm

On an easy run you should be able to hold a full conversation near the upper edge. If talking breaks into short phrases, you have drifted above the band.

How to use

  1. Measure your resting heart rate: count your pulse for a full minute right after waking, before getting out of bed, and enter it in bpm.
  2. Choose how to supply your maximum. If you know it from a lab test or a hard field effort, enter it; otherwise pick the age estimate.
  3. Read your zone 2 band. The two edges are 60% and 70% of your heart-rate reserve on top of your resting rate.
  4. On an easy run, check that you can hold a conversation. Near the upper edge with full sentences means you are in the band.

How the zone is calculated

The Karvonen method sets a target heart rate as THR = (HRmax - HRrest) x intensity + HRrest. The formula comes from Karvonen, Kentala, and Mustala, 'The effects of training on heart rate; a longitudinal study' (1957). This calculator applies the intensities 0.6 and 0.7, the band commonly taught as zone 2, and rounds each edge to a whole bpm.

When you do not know your maximum, the calculator estimates it with the Tanaka formula, HRmax = 208 - 0.7 x age (Tanaka, Monahan, and Seals, Journal of the American College of Cardiology, 2001). The estimate carries real uncertainty: individual maxima sit several beats away from the population line, so a measured maximum is worth having if you train by heart rate regularly. The zone is a guide for easy running, not a medical assessment.

Frequently asked questions

Are my heart rate numbers uploaded?

No. The calculation runs in your browser tab. Your age and heart rates never leave your device, nothing is stored, and the page sets no cookies. Ad slots on the page are served by third-party networks, which follow their own privacy policies.

What is zone 2?

Zone 2 is the easy-effort band most of an endurance week should sit in. On the Karvonen scale used here it is 60% to 70% of your heart-rate reserve. Effort there feels comfortable: breathing is steady and you can speak in full sentences. Runners use it to build an aerobic base without stacking fatigue on top of hard days.

Why the Karvonen method instead of a percentage of maximum heart rate?

A plain percentage of your maximum ignores your starting point. The Karvonen method works from heart-rate reserve, the span between resting and maximum, so the band rises from your own resting rate. Two runners with the same maximum but resting rates of 40 and 60 bpm get different windows, which reflects their different engines.

How good is the age-based maximum estimate?

The calculator uses the Tanaka formula, maximum heart rate = 208 - 0.7 x age, published by Tanaka, Monahan, and Seals in the Journal of the American College of Cardiology in 2001. It tracks the population average better than the old 220-minus-age rule, but individuals land several beats on either side. A maximum measured in a lab or a hard, supervised field test will always beat the estimate.

Is this medical advice?

No. The calculator is a general reference for healthy adults. Heart conditions, blood pressure medication such as beta blockers, and pregnancy all change how heart rate responds to effort, and beta blockers can make the numbers meaningless. If any of these apply, or you are starting exercise after a long break, talk to a doctor before training by heart rate.