Validated equations for metabolic rate, macros, strength, body composition, and cardio training. Calculate instantly in your browser -- nothing stored, nothing tracked.
Find out how many calories your body burns at rest. Results update as you type.
Basal Metabolic Rate
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From metabolic rate to max heart rate, we've got the science covered.
Basal Metabolic Rate -- calories your body burns at rest using Mifflin-St Jeor equation.
Total Daily Energy Expenditure -- your complete daily calorie burn including all activity.
Optimal protein, carb, and fat split for your goal -- muscle gain, fat loss, or maintenance.
Calculate the right deficit for safe, sustainable fat loss with projected timeline.
Daily protein target based on weight, body composition goal, and activity level.
US Navy method body fat percentage -- accurate to within 3% using simple measurements.
Five different formulas (Hamwi, Devine, Robinson, Miller, BMI) for your ideal weight range.
Track water, steps, sleep, and mood. Data stays in your browser and builds your 7-day trend.
See how activities stack up side-by-side. Calorie burn is calculated for your weight using MET values from the Compendium of Physical Activities.
Calorie burn based on 30 minutes of activity. MET values from Ainsworth et al. Compendium of Physical Activities.
Search foods, log your protein intake, and track progress toward your daily goal. All data saved locally.
Customizable Tabata and HIIT intervals with audio cues. Set your work/rest periods and go.
Test your nutrition and fitness knowledge. Pick the winner in each matchup -- all answers backed by real data.
Bite-sized science to fuel your fitness knowledge.
Your body's resting processes -- breathing, circulation, cell repair -- consume the lion's share of your energy. Exercise accounts for just 15-30%.
Through breathing and sweating, your body loses significant water overnight. That's why hydrating first thing in the morning matters so much.
Your body uses 20-30% of protein's calories just to digest it, compared to 5-10% for carbs and 0-3% for fats. It literally costs energy to eat protein.
Sleep deprivation increases ghrelin (hunger hormone) and decreases leptin (satiety hormone), making you crave more food -- especially carbs and sugar.
Evidence-based articles to help you understand the numbers behind your fitness.
Understanding your basal metabolic rate is the foundation of any nutrition strategy. Here's what the science says.
Is weight loss really just math? The answer is yes -- and no. Here's the full picture.
Forget complicated spreadsheets. Here's the practical, beginner-friendly approach to tracking macros.
10 questions about health, nutrition, and fitness myths. How much do you really know? Challenge yourself -- and share your score.
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FitnessCalc uses peer-reviewed equations trusted by sports scientists and nutritionists. Every calculator shows you the formula behind the result -- no black boxes, no hidden algorithms.
Our BMR calculator uses the Mifflin-St Jeor equation, considered the most accurate for most adults. TDEE calculations multiply your BMR by validated activity factors from the scientific literature. Macro calculations follow evidence-based protein, carb, and fat ratios for specific goals.
The One Rep Max calculator uses three independent formulas (Brzycki, Epley, Lombardi) and averages them for the most accurate estimate. Percentage tables help you plan your entire training cycle from hypertrophy to strength peaks.
All calculations happen in your browser. Nothing is sent to a server. Nothing is stored. Nothing is tracked. Your fitness data is yours alone. We built FitnessCalc for people who want answers, not another app tracking their every move.