Instant, science-based tools for weight, nutrition, fitness, and pregnancy — 100% free and private. Every number is calculated right in your browser.
Browse all 12 calculators →Body mass index from your height and weight, with CDC weight categories.
PopularTotal daily calorie needs, plus targets for cutting and bulking.
PopularEstimate body-fat % with the U.S. Navy tape method from a few measurements.
PopularEstimate your due date from your last period, conception, or ultrasound.
PopularSplit your calories into protein, carbs, and fat by goal or custom ratio.
PopularMax heart rate and target training zones, including Karvonen (heart-rate reserve).
BMI, body-fat percentage, ideal weight, and basal metabolic rate — understand what your body is really made of.
4 calculatorsDaily calorie needs, macronutrient splits, hydration, and calories burned by activity.
2 calculatorsTrain smarter with target heart-rate zones and running pace, speed, time, and distance.
2 calculatorsEstimate your due date and find your fertile window and ovulation day from your cycle.
How the menstrual cycle, ovulation timing, and the roughly six-day fertile window fit together, and what the science does and does not tell you.
Classic ideal-weight formulas like Devine and Robinson give a quick target from your height alone, but they were built for clinical dosing, not as a personal health goal.
The popular 35 ml/kg rule, why thirst is a better guide than you think, and how heat, activity, and pregnancy change your needs.
Understand basal metabolic rate, how the Mifflin-St Jeor equation estimates it, and how activity multipliers turn it into your total daily calorie needs.
Learn what a MET is, how to estimate the calories you burn during exercise, and where common activities land.
Learn the difference between pace and speed, how to read and convert pace, and how to use it to plan smarter, better-paced runs.
This tool is for general informational and educational purposes only and is not medical advice. It does not diagnose, treat, or replace care from a qualified professional. Always consult a physician or other qualified healthcare provider about your individual health.