❤️ Health & Fitness Calculators UK
Health and fitness calculators for BMI, calories and everyday wellbeing estimates — quick, general-guidance tools, not a substitute for medical advice.
BMI, calorie needs and due dates are some of the most-searched health calculations, and also some of the most misunderstood — BMI in particular is a simple screening ratio that doesn't distinguish muscle from fat, so it's a starting point for a conversation, not a diagnosis. Calorie and BMR (basal metabolic rate) estimates use established formulas based on height, weight, age and activity level, but individual metabolism varies, and a due date calculation is an estimate based on average pregnancy length, not a guaranteed date.
These calculators are built to give a fast, well-explained estimate using standard, recognised formulas — useful for general awareness, but always a starting point rather than a medical result.
All Health & Fitness calculators
BMI Calculator
Calculate your Body Mass Index using metric or imperial units.
Calorie & BMR Calculator
Find your BMR and daily calorie needs for maintenance, loss or gain.
Pregnancy Due Date Calculator
Estimate your baby's due date and current week from your last period.
VO2 Max Estimator
Estimate your VO2 max from recent run times.
Sleep Cycle Calculator
Find the best bedtime or wake time based on 90-minute sleep cycles.
Body Fat % Calculator (Navy Method)
Estimate body fat percentage using the US Navy tape method.
Running Pace Calculator
Convert running pace to finish time for any distance.
Daily Water Intake Calculator
Estimate how much water you should drink per day.
Heart Rate Zone Calculator
Find your training heart rate zones by age.
Frequently asked questions
Is BMI an accurate measure of health for everyone?
BMI is a useful general screening tool but doesn't account for muscle mass, frame size, age or ethnicity, so it can be misleading for athletes, older adults or anyone with an atypical body composition. It's best used alongside other measures, not in isolation.
How accurate is a pregnancy due date calculator?
Due date calculators estimate based on average pregnancy length (typically 40 weeks from the last menstrual period), but only a small percentage of babies actually arrive on the calculated date — it's a useful planning estimate, not a fixed deadline. Your midwife or doctor's dating scan is the more accurate reference.