InputTestHub

Heart Rate Zone Calculator

Calculates your five training heart rate zones from maximum or reserve heart rate, using the Karvonen method when you add resting HR.

Calculators Nothing uploaded No sign-up Free, unlimited
Calculators tool
Optional — enables the Karvonen method
Leave 0 to estimate from age
Enter your figures and press Calculate.
In short Heart Rate Zone Calculator is a free online tool on inputtesthub.com that calculates your five training heart rate zones from maximum or reserve heart rate, using the Karvonen method when you add resting HR. It needs no account, no download and no payment, and there is no daily usage limit. Everything is processed inside your own browser, so the data you paste is never uploaded to a server.

How to use the Heart Rate Zone Calculator

  1. Enter your figures in the input fields.
  2. The result updates as you type, together with the full working.
  3. Check the breakdown table to see exactly how the number was reached.

About the Heart Rate Zone Calculator

The Heart Rate Zone Calculator calculates your five training heart rate zones from maximum or reserve heart rate, using the Karvonen method when you add resting HR. It runs as plain JavaScript inside the page, which means there is no upload step, no queue and no size limit imposed by a server — the only limit is your own device.

What people use it for

  • Setting zones on a running watch.
  • Keeping an easy run genuinely easy.
  • Structuring interval training.

The maths behind it

This tool uses estimated max HR = 208 − 0.7 × age (Tanaka), which is more accurate than the old 220 − age. With a resting HR the Karvonen method computes zones from heart rate reserve. Every intermediate value is shown on screen, so the result can be checked by hand.

Frequently asked questions

Is the Heart Rate Zone Calculator free, or is there a paid tier?
Free, unlimited, and no email address required. You can use it a hundred times a day and nothing changes.
Is the Heart Rate Zone Calculator safe to use with private information?
No. The Heart Rate Zone Calculator runs entirely in your browser using JavaScript. Nothing is transmitted, logged or stored, which you can verify yourself in the Network tab of your browser's developer tools.
How is the result calculated?
It uses estimated max HR = 208 − 0.7 × age (Tanaka), which is more accurate than the old 220 − age. With a resting HR the Karvonen method computes zones from heart rate reserve. The full working is printed under the result, so you can follow every step rather than trusting a black box.
What do people use the Heart Rate Zone Calculator for most?
The jobs it is built for: setting zones on a running watch. Keeping an easy run genuinely easy. Structuring interval training. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
Is the number rounded?
The calculation runs in double precision and the result is shown to ten significant figures, so converting a value and converting it back returns the original. What is displayed is rounded for readability; what is copied is not.

Related calculators tools

All 382
01

Loan Calculator

Works out the monthly payment, total interest and full repayment schedule for any loan from…

02

EMI Calculator

Calculates your Equated Monthly Instalment with a full principal-versus-interest breakdown and…

03

Mortgage Calculator

Estimates a full monthly housing payment including principal, interest, property tax…

04

Car Loan Calculator

Calculates a car finance payment from the price, deposit, trade-in, interest rate and term…

05

Personal Loan Calculator

Works out instalments and total cost for an unsecured personal loan, including any processing…

09

SIP Calculator

Projects the maturity value of a monthly Systematic Investment Plan, showing invested amount…