Free Health Calculators

Quick, no-sign-up tools that turn the numbers your Apple Watch already tracks into something you can actually use.

Heart rate

Resting Heart Rate by Age

See how your resting heart rate compares to healthy ranges for your age and sex.

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Heart rate

Target Heart Rate Zones

Find your max heart rate and five training zones, including the fat-burning and Zone 2 ranges.

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Cardio fitness

VO2 Max Calculator

Estimate your VO2 max — the "Cardio Fitness" number Apple Watch reports — and rate it by age.

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Activity

Steps to Calories

Convert daily steps into calories burned and distance walked, personalised by weight and pace.

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Tools that pair with your Apple Watch

Your Apple Watch already records the numbers that matter most for everyday health — resting heart rate, cardio fitness, and daily steps. These calculators help you make sense of those numbers without a spreadsheet or a subscription. Type in what your watch shows and get an instant, plain-English read on where you stand.

Each tool runs entirely in your browser. Nothing you enter is stored or sent anywhere, which fits the way Health Genie works: your health data stays on your device.

Frequently asked questions

Are these health calculators free?

Yes. Every calculator on this page is free to use, runs entirely in your browser, and requires no sign-up. None of the values you enter are stored or sent anywhere.

Do these calculators need an Apple Watch?

No. The calculators work with numbers you type in, so anyone can use them. They are designed to pair well with figures an Apple Watch reports — such as resting heart rate, cardio fitness (VO2 max) and daily steps — but a watch is not required.

How accurate are the results?

The calculators use established formulas and published reference ranges, so results are good estimates for general wellness and education. They are not medical measurements, and individual physiology varies. For health concerns, speak with a doctor.

One number, every morning

Health Genie reads your Apple Watch steps and resting heart rate and gives you a single Vitality Score each morning — no dashboards to decode.

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