Simple, free calculators to help you understand calories, body metrics, protein, hydration, and more.
Choose a goal and we'll help you find the right calculator.
Understand your weight, body fat, and a healthy range for your height.
Figure out how many calories you burn, and how many to eat.
Set protein and macro targets to support training.
Tell us what you're trying to understand and we'll point you in the right direction.
This quiz helps you find the right free tool — it doesn't diagnose any condition or provide medical treatment.
The four calculators people reach for first.
Check your Body Mass Index and see what it means for your health.
Set your daily calorie target for your goal.
Find your Total Daily Energy Expenditure.
Find your ideal daily protein intake.
Eight focused calculators, whatever your goal.
Check your Body Mass Index and see what it means for your health.
Set your daily calorie target for your goal.
Find your Total Daily Energy Expenditure.
Find your ideal daily protein intake.
Get your daily protein, carb, and fat targets.
See how much water you should drink daily.
Estimate body fat using the US Navy method.
Find a healthy target weight range for your height.
A quick reference if you already know your goal.
Understand BMI
BMI Calculator
Estimate calorie needs
Calorie Calculator
Estimate daily energy expenditure
TDEE Calculator
Estimate protein needs
Protein Calculator
Set macro targets
Macro Calculator
Estimate hydration needs
Water Intake Calculator
Estimate body fat
Body Fat Calculator
Estimate a weight range
Ideal Weight Calculator
Pick the tool that matches what you want to understand.
Fill in a few details — usually height, weight, age, and activity level.
See your result instantly, calculated right in your browser.
Each result comes with plain-language context, not just a number.
These calculators provide general estimates based on the information you enter. Individual needs can vary.
A calculator gives you a starting point. Our guides help you understand what the numbers mean.
Training and movement content to pair with your TDEE and calorie numbers.
Visit FitnessFood and meal planning context for your calorie, protein, and macro results.
Visit NutritionEveryday habits — hydration included — to round out your routine.
Visit WellnessSkincare and self-care routines that complement your body-metric results.
Visit BeautyPlain-language methodology for every tool — no black boxes.
A BMI calculator estimates Body Mass Index from your height and weight and shows which standard weight-status category it falls into.
Methodology: Uses the standard BMI formula — weight divided by height squared — and places your result into the standard adult BMI categories.
Open BMI CalculatorA calorie calculator estimates how many calories to eat each day to maintain, lose, or gain weight, based on your stats and activity level.
Methodology: Estimates your baseline energy needs with the Mifflin-St Jeor equation, then adjusts the target based on the goal you select.
Open Calorie CalculatorA TDEE calculator estimates the total calories your body burns in a day, including activity — a useful starting point for a calorie target.
Methodology: Estimates your Basal Metabolic Rate with the Mifflin-St Jeor equation, then multiplies it by an activity factor.
Open TDEE CalculatorA protein calculator estimates how many grams of protein to eat per day based on your body weight and goal.
Methodology: Multiplies your body weight by a gram-per-kilogram range you select, based on your activity and goal.
Open Protein CalculatorA macro calculator breaks your daily calorie target into protein, carbohydrate, and fat grams.
Methodology: Uses the Mifflin-St Jeor equation to estimate daily calories, then splits that total into protein, carb, and fat targets based on your goal.
Open Macro CalculatorA water intake calculator estimates how many ounces of water to drink daily based on your body weight.
Methodology: Estimates a daily fluid target from your body weight using a standard ounces-per-pound guideline.
Open Water Intake CalculatorA body fat calculator estimates the percentage of your body made up of fat, using circumference measurements rather than just weight.
Methodology: Uses the US Navy method — a set of body circumference measurements — to estimate body fat percentage.
Open Body Fat CalculatorAn ideal weight calculator estimates a healthy weight range for your height, based on a standard reference formula.
Methodology: Uses the Hamwi formula, a standard height-based method, to estimate a healthy target weight range.
Open Ideal Weight CalculatorThese calculators use standard, widely-referenced formulas. They provide estimates, not medical-grade or clinically diagnostic results.
Use every calculator without a subscription.
No unnecessary account creation.
Simple explanations instead of confusing data.
General estimates, not medical diagnoses.
We're building more practical tools to help you understand your health, fitness, nutrition, and everyday routines.
Macro Planner
Running Pace Calculator
Sleep Calculator
One Rep Max Calculator
Healthy Habit Tracker
Have an idea for another calculator? Let us know or visit the blog for what's new.
Yes. Every calculator on this page is completely free to use, with no hidden fees.
No. All eight tools work instantly in your browser — no sign-up, login, or email required.
They use standard, widely-referenced formulas (like the BMI formula, the Mifflin-St Jeor equation, or the US Navy body-fat method) to give a general estimate. Actual results can vary based on factors a simple calculator can’t measure, like muscle mass or bone density.
No. They’re educational tools meant to help you understand common fitness and nutrition metrics. They don’t diagnose any condition and aren’t a substitute for advice from a qualified healthcare professional.
If you’re not sure, start with the BMI Calculator, or try the “Find My Tool” quiz above — it asks a couple of quick questions and points you to the right tool.
They can give you a helpful starting point, like a calorie target or protein goal, but they work best alongside guidance from a healthcare provider or registered dietitian, especially if you have a specific health condition.
It depends on the tool, but most just need your height, weight, age, sex, and activity level. Each calculator tells you exactly what to enter.
Yes. Two people with the same height and weight can have very different body compositions, so treat every result as a general estimate, not a fixed target.
These calculators provide general estimates for informational and educational purposes. Results can vary based on individual circumstances and should not be considered medical advice or a diagnosis.
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