Calorie needs, metabolism, body composition, pregnancy dating, running pace, and heart rate zones, practical calculators for everyday health and fitness questions.
Estimate daily calorie needs by activity level and goal.
Calculate your Body Mass Index, metric or imperial.
Find your resting metabolic rate.
Estimate body fat % using tape measurements.
See estimates from four established formulas.
Compare energy needs across every activity level.
Get a daily protein intake range for your goals.
Estimate your due date and current week.
Find your running pace and predicted race times.
Find your training heart rate zones.
Daily protein, carb, and fat targets.
Estimate calories burned by activity and duration.
Pinpoint fertile window and peak ovulation dates.
Track menstrual cycle phases and next period forecast.
Determine personalized daily hydration goals in liters, ounces, and glasses.
Track healthy gestational weight gain week-by-week using IOM guidelines.
Compute BSA using Mosteller, Du Bois, Haycock, and Gehan formulas with BMI.
Calculate target daily calorie intake and weight loss timeline with macro splits.
Convert daily step count to miles, kilometers, calories burned, and walking time.
Estimate blood alcohol content, impairment levels, and time until sober using Widmark formula.
Predict single-rep maximum strength, compare 6 clinical formulas, and calculate percentage loads.
Official AR 600-9 tape test body fat percentage and military readiness standards.
Calculate eating windows, fasting schedules (16:8, 18:6, OMAD), and autophagy timeline.
Determine hourglass, pear, rectangle, or apple body type and Waist-to-Hip Ratio health score.
Compute lean muscle weight and fat mass using Boer, James, and Hume clinical formulas.
Predict future adult stature using clinical Mid-Parental Tanner formulas and growth models.
Assess aerobic endurance using Cooper 12-min run, Rockport walk, or resting heart rate.
Calculate high, medium, and low carb day calories and macros for body recomposition.
Calculate powerlifting strength coefficients across bodyweights for squat, bench, and deadlift.
Estimating daily calorie needs, checking a BMI figure, or working out target heart rate zones for training are common questions in fitness and health planning, usually answered with standard formulas that take just a few inputs like weight, height, age, and activity level. This category groups those calculators together, all working from formulas widely used in fitness and nutrition guidance.
Body composition tools (BMI, Body Fat, Ideal Weight) estimate how your body measurements compare to standard ranges. Energy and nutrition tools (Calorie, BMR, TDEE, Protein, Macro, Calories Burned) cover how much energy your body uses and needs. Pace Calculator and Target Heart Rate Calculator support running and cardio training specifically, while Pregnancy Due Date Calculator estimates a due date from your last menstrual period.
BMR (Basal Metabolic Rate) is the energy your body burns at complete rest just to stay alive. TDEE (Total Daily Energy Expenditure) adds your physical activity on top of BMR, providing a realistic estimate of total daily calories burned.
BMI is a rapid population-level screening metric based on height and weight. Because it does not distinguish muscle mass from adipose tissue, body fat percentage calculations provide a more detailed evaluation for athletic builds.
It calculates based on Naegele rule using the standard 280-day gestation from your last menstrual period. Clinical ultrasound assessments performed by healthcare professionals provide the definitive dating.
No. All tools on Calc369 provide mathematical estimates based on peer-reviewed physiological formulas for educational purposes only. Always consult a physician or registered dietitian for medical guidance.