About Healthly

Healthly shows how your heart rate, weight or your child's growth compares with ranges published by the CDC, the National Institutes of Health, the World Health Organization and the American Heart Association. Our calculators are for general information. They can't diagnose a condition or replace advice from your doctor.

What Healthly does

Choose a number, such as your resting heart rate, your weight or your child's age, and Healthly shows how it compares with ranges from trusted public health sources. Each answer starts with a short, clear result, followed by a chart, a full table and tips on how to measure.

The numbers you choose stay in your browser. They aren't sent to us or stored.

Where our numbers come from

Resting heart rate

Typical resting heart rates by age and sex come from a national CDC health survey of children, teens and adults in the United States, published in 2011. The survey reports heart rates by age group, such as adults ages 20 to 39, so every age in a group shares the same numbers.

For anyone 12 and older, we use the normal resting range of 60 to 100 bpm from the American Heart Association. When a heart rate is lower or higher than 99 out of 100 people the same age, we call it well below or well above usual.

Exercise heart rate

Your exercise zones are based on an estimated maximum heart rate of 220 minus your age, for women and men. This is the estimate on the American Heart Association target heart rate chart. Moderate exercise is about 50% to 70% of that maximum, and vigorous exercise is about 70% to 85%. A heart rate at exactly 70% counts as vigorous.

For women, we also show a second estimate of 206 minus 0.88 times age, from a 2010 study by Gulati and colleagues in the journal Circulation. It's shown for comparison and doesn't change your zones.

Child growth

For babies and toddlers from birth to 23 months, we use the World Health Organization growth charts for weight and length. From 24 months, including age 2, we use the 2000 CDC growth charts. If a child's measurement falls between two published percentiles, we estimate the percentile in between.

Most healthy children are between the 5th and 95th percentiles. The 50th percentile is the middle, not a target.

Adult weight and height

Our adult calculators use body mass index (BMI). BMI is your weight in kilograms divided by your height in meters squared. A healthy weight is a BMI of 18.5 to 24.9, from the CDC adult BMI categories. We calculate BMI the way the National Heart, Lung, and Blood Institute does.

We show BMI to one decimal place without rounding up, so 24.96 shows as 24.9 and counts as a healthy weight. BMI is a screening tool. It doesn't measure body fat.

How we keep pages up to date

When a source changes, we update the page.

Medical disclaimer

Healthly is for general information only. It isn't medical advice and can't diagnose or treat any condition. Talk with your doctor about your own numbers. If you think you're having a medical emergency, call 911 or your local emergency number.

Sources