Health Calculators
Free calculators for body mass index, daily calorie needs and sleep timing. Each result is an estimate, and each page explains the formula behind it.
4 calculators each one also works as a widget
- BMI Calculator Adult BMI with its category, the healthy weight for your height and how far you are from it.
- Sleep Calculator Find when to go to bed or when to wake up, based on 90-minute sleep cycles.
- BMR Calculator Estimate your basal metabolic rate and how many calories you need each day.
- TDEE Calculator Estimate how many calories you burn in a day, with calorie goals and a macro split.
Which Health Calculator Do You Need?
The BMI Calculator compares your weight with your height. It shows which adult weight category the result falls in and the healthy weight range for your height.
For calories, start with the BMR Calculator. Your basal metabolic rate is the energy your body uses at rest. The TDEE Calculator adds your activity level to estimate the calories you burn in a whole day, which is the number to plan from when you want to lose, keep or gain weight.
The Sleep Calculator counts in 90-minute sleep cycles, so you can pick a bedtime or an alarm time that falls at the end of a cycle instead of in the middle of one.
From BMR to a Daily Calorie Number
The BMR Calculator can use three published formulas: Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle, which needs your body fat percentage. The TDEE Calculator multiplies your BMR by an activity factor, from 1.2 for a desk job with little exercise up to 1.9 for hard daily training or physical work.
The result is a daily maintenance estimate. Eating a little less than it tends to lead to weight loss over time, and eating more to weight gain. Check your progress over a few weeks and adjust, because real needs can sit a few hundred calories either side of any formula.
How the Sleep Calculator Counts
It adds the time you usually need to fall asleep, 14 minutes unless you change it, and then counts whole 90-minute cycles. Waking at the end of a cycle, when sleep is lighter, often feels easier than waking in the middle of deep sleep.
What These Numbers Can Tell You
Each calculator uses a published formula and gives an estimate for a typical adult. Muscle, age, pregnancy, illness and medication can all move your real numbers. Use the results as a starting point, and talk to a doctor or a dietitian before a big change in diet or weight.
Children and teenagers need a different method. For ages 2 to 19, the CDC compares BMI with growth charts for the child's age and sex and reports a percentile, which the adult BMI Calculator does not do.
Frequently Asked Questions
What is the difference between BMR and TDEE?
BMR is the energy you burn at complete rest. TDEE is your BMR plus everything you burn by moving, from walking to exercise, so it is always higher. Plan calorie goals from your TDEE.
Is BMI accurate?
BMI is a quick screening number that doctors follow up with other checks. It does not measure body fat, so a very muscular person can have a high BMI and still be healthy. The BMI Calculator page explains its limits and links to the CDC and WHO.
Are the health calculators free?
Yes. They are free, need no account, and do the math in your browser.