Free Fitness & Nutrition Calculators

Why Use Fitness Calculators?

Whether you are trying to lose weight, build muscle, or simply maintain your health, understanding your body's nutritional needs is the foundation of any successful fitness journey. Fitness calculators transform complex scientific formulas into instant, actionable numbers tailored specifically to you.

Understanding Your Energy Balance

At its core, weight management comes down to energy balance — the relationship between the calories you consume and the calories you burn. Your Total Daily Energy Expenditure (TDEE) represents the total number of calories your body uses in a day, combining your basal metabolic rate with the energy spent on physical activity, digestion, and daily movement. Knowing this number is the single most important step in planning your nutrition.

Your Basal Metabolic Rate (BMR) accounts for 60-75% of your daily calorie burn. It represents the energy your body needs just to stay alive — breathing, circulating blood, maintaining body temperature, and repairing cells. By calculating your BMR and multiplying it by your activity level, you get your TDEE, which tells you exactly how many calories you need to eat to maintain your current weight.

Setting Effective Goals

Once you know your TDEE, you can create a precise plan for your goals. To lose weight, you need a calorie deficit — typically 300-500 calories below your TDEE for sustainable fat loss. To gain muscle, you need a modest surplus of 200-400 calories, combined with adequate protein intake and a structured training program.

Our Macro Calculator takes this a step further by breaking your calorie target into specific amounts of protein, carbohydrates, and fats. Research consistently shows that tracking macronutrients, not just calories, leads to better body composition outcomes. Higher protein intake preserves muscle during a cut, while adequate carbohydrates fuel your workouts and support recovery.

Tracking Your Training

Fitness is not just about nutrition. The Calories Burned Calculator helps you understand the energy cost of different activities, from running and cycling to weight training and yoga. This information is essential for adjusting your nutrition on training versus rest days.

For strength athletes, the One Rep Max (1RM) Calculator estimates your maximum strength from submaximal lifts, allowing you to program your training percentages accurately. And if you are a runner, the Pace Calculator helps you plan race strategies, predict finish times, and track your pace across different distances.

The Science Behind the Numbers

All of our calculators are built on peer-reviewed research and established scientific formulas. The BMR calculation uses the Mifflin-St Jeor equation, which studies have shown to be the most accurate for the general population. Body fat estimation uses the US Navy method, validated by the Department of Defense. One-rep max calculations use four established formulas (Epley, Brzycki, Lombardi, and O'Conner) and average the results for greater accuracy.

We believe that everyone deserves access to accurate, science-backed fitness tools without having to pay for expensive apps or sign up for subscriptions. Every calculator on FitCalc is completely free, requires no registration, and works instantly in your browser.

Getting Started

If you are new to fitness tracking, start with our TDEE Calculator — it is the foundation for everything else. From there, use the Calorie Calculator to set a daily target and the Macro Calculator to plan your meals. As you progress, explore our database of over 350 foods with detailed nutrition information and our library of 80+ activities with accurate calorie burn estimates.