Using Calories and Macros as a Starting Point
How to interpret calorie and macro estimates without treating them as exact prescriptions.
Health tools
Health and Fitness Calculators
Estimate calorie needs, body metrics, training targets and nutrition splits with careful health disclaimers and plain formula notes.
Health and fitness calculators can give a useful range, but they cannot read your full health history, training load or recovery. Treat the numbers as planning inputs rather than personal medical advice.
These tools are built for everyday checks such as calorie targets, macro splits, BMI, pace and training zones. Revisit the inputs as your weight, schedule, goals or activity level changes.
11 calculators
Use these estimates as starting points for training, nutrition and body measurements, with clear limits where health context matters.
HealthCaloriesEstimate daily maintenance calories using the Mifflin-St Jeor equation and an activity multiplier.HealthMacrosSplit daily calories into protein, fat and carbohydrate targets using body weight and preferred fat percentage.HealthBMICalculate adult body mass index from height and weight, with standard category ranges.HealthPaceCalculate running pace, finish time or distance from any two values, with pace per kilometre, pace per mile and average speed.HealthBody FatEstimate body fat percentage from circumference measurements using the US Navy method.HealthBMREstimate basal metabolic rate using the Mifflin-St Jeor equation, then compare it with activity-adjusted calorie needs.HealthOne Rep MaxEstimate one rep max and training percentages from weight lifted and reps completed.HealthHeart ZonesEstimate maximum heart rate and training zones from age and resting heart rate.HealthWater IntakeEstimate daily fluid needs from body weight, activity and warm conditions.HealthDue DateEstimate a pregnancy due date from the first day of the last menstrual period.HealthWaist Hip RatioCalculate waist-to-hip ratio from waist and hip measurements, with category notes and clear health limits.
Guides
Useful reading for health questions
Read the background, then move straight into the linked calculators when you need a result.
BMR, TDEE and Calories: What Is the Difference?
Understand basal metabolic rate, activity estimates and how they become a daily calorie target.
Heart Rate Zones for Running, Cycling and Fitness
How to use heart rate zones for easy training, threshold work and recovery without over-reading the numbers.
BMI, Body Fat and Waist-to-Hip Ratio Compared
What common body measurement calculators can and cannot tell you about health context.
Calorie Deficit, Maintenance and Surplus: How to Choose
How to move from estimated maintenance calories to a fat loss, maintenance or muscle gain target.
Running Pace vs Speed: What to Use in Training
How pace, speed, distance and heart rate zones work together for runners and cyclists.