About WeightWise

WeightWise is a collection of free, accurate health calculators designed to help you understand your body and make informed decisions about your weight and fitness.

What we offer

Six calculators covering the most commonly needed health metrics: BMI, calorie deficit, basal metabolic rate, ideal weight, body fat percentage, and weight loss timeline. Every calculator works instantly in your browser — no account, no email, no tracking.

How the calculators work

Each calculator is built on established, peer-reviewed formulas used in clinical and research settings. We use the Mifflin–St Jeor equation for BMR, the WHO BMI classification, the U.S. Navy circumference method for body fat, and WHO healthy BMI ranges for ideal weight. Where relevant, we show the exact formula used so you can verify the maths yourself.

Accuracy and limitations

These calculators provide estimates based on population-level research. Individual results vary based on factors including muscle mass, hydration, age, and genetics. The results are intended as useful reference points, not clinical diagnoses. Always consult a qualified healthcare professional before making significant changes to your diet or exercise routine.

Contact

Questions or feedback? Reach us at hello@usefitcalc.com.