Exercise Scientist Turns a Personal Heart Scare into a Free Training Tool

PALATINE, Ill. - Sept. 15, 2026 - PRLog -- "An AFib episode makes you pay much closer attention to your heart," said Ethan Peterson, founder of CalculateMyHeartRate.com. "Because of my exercise science background, I knew the Karvonen method could give me a better estimate than the standard formulas. I first built the calculator for myself. Then I realized it could also help people managing similar concerns, as well as anyone who wants to be more deliberate about cardio training."

A little over a year ago, Ethan, an exercise science graduate, experienced an Atrial Fibrillation (AFib) episode. It changed how he approached cardio training and eventually led him to build CalculateMyHeartRate.com, a free tool that calculates personal heart rate zones using the Karvonen formula and several other methods.

Heart rate zone training is widely used in exercise science, yet many online calculators still rely on the basic 220-minus-age formula, a rough estimate that ignores a person's resting heart rate or current fitness. That kind of guess is fine until your heart reminds you it isn't tracking a number, it's tracking you. After the AFib episode, Ethan looked for a free tool that incorporated both measures but found that the available options did not meet his needs.

CalculateMyHeartRate.com primarily uses the heart rate reserve method, also known as the Karvonen method, which accounts for age and resting heart rate. Users can also compare results from the Tanaka, Gulati, and Nes formulas. The site includes a resting heart rate tracker for following changes over time and a free widget that coaches, trainers, and fitness bloggers can embed on their own websites.

The calculator is intended for anyone who uses heart rate zones to plan workouts, including beginners, coaches, and endurance athletes training for running, cycling, or triathlon events.

The site is free to use and does not require an account.

A single AFib episode was enough to send Ethan looking for better data. Now anyone chasing that same clarity can get it for free, in under a minute, no app or account required.

For more information, visit https://www.CalculateMyHeartRate.com

About CalculateMyHeartRate.com

CalculateMyHeartRate.com is a free browser-based calculator that estimates personal heart rate training zones using the Karvonen, or heart rate reserve, formula and several alternative methods. The site was created by exercise science graduate Ethan Peterson after a personal health experience prompted him to reconsider how he monitored cardio intensity. It serves athletes and recreational exercisers seeking a clearer view of their training zones.

Media Contact: Ethan Peterson | info@calculatemyheartrate.com | CalculateMyHeartRate.com

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