Weight & Calories
Calorie Calculator
Daily calories to maintain, lose or gain weight, with built-in safety minimums.
TDEE Calculator
Total daily energy expenditure: what you burn in a full day.
BMR Calculator
Calories burned at rest, compared across three published equations.
Calorie Deficit & Goal Date Calculator
Estimate when you could reach a goal weight at a daily deficit.
Macro Calculator
Split your calories into grams of protein, carbs, and fat.
Protein Calculator
Daily protein needs in grams from your weight and activity.
Body Composition
BMI Calculator
Find your Body Mass Index and adult weight category from height and weight.
Body Fat Calculator
Estimate body fat percentage with the U.S. Navy tape-measure method.
Lean Body Mass Calculator
Estimate lean body mass with the Boer, James and Hume formulas.
Ideal Weight Calculator
See an ideal weight range using four classic formulas and BMI.
Waist-to-Hip Ratio Calculator
Waist-to-hip ratio with WHO health-risk cutoffs.
Fitness & Training
Pace Calculator
Work out running pace, finish time or distance in miles or km.
Heart Rate Zone Calculator
Max heart rate and five training zones, with Karvonen option.
One-Rep Max Calculator
Estimate your 1RM from a set of reps, with a training % chart.
Calories Burned Calculator
Calories burned for 18 activities using 2024 Compendium MET values.
Steps to Calories Calculator
Convert steps into distance and calories burned walking.
Pregnancy
Wellness
Why use SimpleFitCalc?
Most online health calculators give you a number and nothing else. We think you deserve to know where that number comes from. Every tool on SimpleFitCalc is built on a published, peer-reviewed formula or an official guideline — such as the Mifflin-St Jeor equation, CDC BMI categories, WHO waist-to-hip cutoffs or the Compendium of Physical Activities — and each page explains the math, walks through worked examples, and links directly to the original source.
Private by design
Every calculation runs entirely in your browser. Your age, weight, measurements and dates are never sent to us or stored anywhere, and there's no sign-up. Close the tab and they're gone.
Safety built in
Calorie tools never suggest weight-loss targets below common minimums of 1,200 calories a day for women or 1,500 for men, and they flag goals that are better handled with a professional. Every calculator clearly lists its limitations and the groups it may not suit, such as children, pregnant people and people with certain medical conditions.
How to get the most out of these tools
Start with the basics: the BMI Calculator and Waist-to-Hip Ratio Calculator give a quick snapshot of where you stand. Next, find your maintenance calories with the TDEE Calculator, then set a goal with the Calorie Calculator and split it into protein, carbs and fat with the Macro Calculator. If you exercise, the fitness tools help you plan runs, find heart rate zones and estimate calories burned.
Remember that every formula predicts an average. Your own results — how your weight, energy and performance change over weeks — are the best guide. When in doubt, talk to a doctor or registered dietitian. Read our full medical disclaimer.
These tools give estimates for general information, not medical advice. Read our disclaimer.