Free Health & Fitness Calculators
These free health and fitness calculators estimate energy needs, macronutrients, body composition, strength and blood-sugar averages using published, peer-reviewed equations, including Mifflin-St Jeor for BMR and the U.S. Navy circumference method for body fat. Each page names its formula so results can be checked.
All 6 health & fitness tools
BMR Calculator
Free BMR calculator: your basal metabolic rate by the Mifflin-St Jeor, Harris-Benedict and Katch-McArdle formulas, plus daily calories (TDEE) by activity level.
🥗Macro Calculator
Free macro calculator: daily calories and grams of protein, carbs and fat to lose, maintain or gain weight, with balanced, high-protein, low-carb and keto presets.
🏋️One Rep Max Calculator
Free one rep max calculator: estimate your 1RM from any weight and reps with the Epley, Brzycki, Lombardi, O'Conner and Wathan formulas, plus a 50–100% chart.
🩸A1C Calculator
Free A1C calculator: convert A1C to estimated average glucose (eAG) in mg/dL and mmol/L, or glucose to A1C, with the ADA ranges for normal, prediabetes and diabetes.
📏Body Fat Calculator
Free body fat calculator: estimate your body fat percentage from height, neck, waist and hip with the U.S. Navy method, plus fat mass, lean mass and ACE category.
🥚Protein Calculator
Free protein calculator: how many grams of protein you need per day for your weight and goal, from the 0.8 g/kg RDA to muscle gain and fat loss, split per meal.
Health & fitness guides
All guides →How to calculate macros: estimate BMR with Mifflin-St Jeor, multiply by activity for TDEE, set a calorie target, then split it into grams at 4, 4 and 9 kcal.
How to calculate body fat percentage with the U.S. Navy tape method, step by step with a worked example, plus how DEXA, skinfolds and BIA compare.
Health & fitness terms explained
Glossary →- Acceptable Macronutrient Distribution Range (AMDR)
- The Acceptable Macronutrient Distribution Range (AMDR) gives the share of daily calories from carbohydrate, fat and protein linked to adequate nutrients and lower chronic disease risk.
- Basal Metabolic Rate (BMR)
- Basal metabolic rate (BMR) is the energy the body uses at complete physical, mental and digestive rest; it is the largest part of daily calorie needs and is usually estimated by formula.
- Mifflin-St Jeor Equation
- The Mifflin-St Jeor equation is a 1990 formula that estimates resting energy expenditure in calories per day from weight, height, age and sex; it is widely used to estimate BMR.
- Total Daily Energy Expenditure (TDEE)
- Total daily energy expenditure (TDEE) is the total calories the body burns in a day, combining resting metabolism, the thermic effect of food and all physical activity.
Frequently asked questions
Which BMR formula do these calculators use?
The BMR and macro calculators use the Mifflin-St Jeor equation, which is widely used to estimate resting energy needs in healthy adults.
How accurate is the body fat calculator?
It uses the U.S. Navy circumference method, which estimates body fat from height, neck, waist and (for women) hip measurements. It is a practical estimate, typically within a few percentage points of lab methods, not a clinical measurement.
Are these calculators medical advice?
No. They are educational estimates. For medical questions, including anything about A1C or blood sugar, talk to a doctor or registered dietitian.