BMI Calculator
Your body mass index and its standard adult category.
Under 15 seconds
Open Calculator4 calculators in this category
Health Calculators
These calculators turn a few body measurements into commonly used health estimates. The BMI calculator places your body mass index in the standard adult ranges, the BMR calculator estimates the energy your body uses at rest with the Mifflin-St Jeor equation, the calorie calculator adds an activity level to estimate daily energy needs, and the water intake calculator gives a simple daily hydration estimate from body weight and activity. Each tool accepts metric or imperial units, shows the formula it uses and explains its assumptions. They are general, informational estimates: individual needs vary with age, health conditions, medication, climate and many other factors, and none of these tools diagnoses or treats anything. For personal guidance, speak with a doctor or a qualified health professional.
Featured health calculators
Free, instant and mobile-friendly. Pick a tool and start with your own numbers.
Calorie Calculator
Estimate your BMR and daily calorie needs from your activity level.
Under 30 seconds
Open CalculatorBMR Calculator
Estimate the calories your body uses at complete rest.
Under 30 seconds
Open CalculatorWater Intake Calculator
Estimate how much water you may need each day.
Under 30 seconds
Open CalculatorAbout health calculators
What this category covers, who it is for, and where it helps most.
What these calculators do
They apply widely used, published formulas to your height, weight, age, sex and activity level, and show the method and assumptions behind each estimate.
Who should use them
Adults who want a general reference point for body mass index, energy needs or hydration — as a starting point for a conversation with a professional, not a substitute for one.
Important note
Results are estimates for information only and are not medical advice, diagnosis or treatment.
Common use cases
- Check where a BMI falls in the standard adult ranges
- Estimate resting energy use (BMR)
- Estimate daily calorie needs for an activity level
- Get a rough daily water intake estimate
Frequently asked questions
Common questions about health calculators.
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