Health & Fitness Calculators
Our free UK health calculators are based on evidence-based guidelines from the NHS and Public Health England. They cover the most commonly used health and fitness metrics to help you understand your body and make informed lifestyle choices.
These tools are for general educational purposes and are not a substitute for professional medical advice. They use widely recognised formulas such as the BMI formula from the World Health Organisation, the Mifflin-St Jeor equation for calorie estimation, and NHS sleep cycle recommendations.
- ✓Calculate your Body Mass Index (BMI) using NHS weight classifications
- ✓Estimate your daily calorie needs based on activity level and goal
- ✓Find the best bedtime or wake-up time based on 90-minute sleep cycles
- ✓Calculate daily water intake based on weight and exercise
All Health & Fitness Calculators
UK BMI Calculator — Body Mass Index (NHS)
Free BMI calculator for UK adults. Use this BMI calculator to find your BMI and check if you are a healthy weight. This BMI calculator works for women and men. Enter your height and weight and your estimated BMI appears in seconds. You will also see your NHS weight category and your healthy weight range for your height. BMI is a useful guide, but it is just one piece of the picture. It does not measure body fat directly. Muscle, age, and body shape all affect what your number really means.
PopularSleep Calculator
Find the optimal times to wake up based on 90-minute sleep cycles so you wake feeling refreshed instead of groggy.
PopularUK Calorie Calculator — TDEE & Daily Calories
Free UK calorie calculator. Calculate your Total Daily Energy Expenditure (TDEE) and find exactly how many daily calories your body needs to lose weight, maintain, or build muscle mass. Uses the Mifflin-St Jeor formula for basal metabolic rate (BMR) — the most accurate method for estimating the calories your body burns at rest. Includes thermic effect of food, physical activity multipliers, and calorie counting targets. Set your goal and get a precise daily calorie figure instantly.
Water Intake Calculator
Free water consumption calculator — find out the amount of water you should drink daily based on your weight and activity level. Get your recommended water intake in litres and glasses based on NHS hydration guidelines. Staying hydrated helps regulate body temperature, supports weight loss and losing weight goals, and boosts energy and concentration. Your body loses water constantly through breathing, sweating, and urination — this calculator helps you stay hydrated throughout the day.
NHS Blood Pressure Checker — Blood Pressure Chart UK
Free NHS blood pressure checker for UK adults. Enter your systolic and diastolic blood pressure reading and see instantly which NHS category it falls into — low, ideal, pre-high, or hypertension stage 1 or 2. Includes the full NHS blood pressure chart so you can see where your reading sits. High blood pressure (hypertension) affects around 1 in 3 adults in the UK and is a leading risk factor for heart attack and stroke. Most people with high blood pressure have no symptoms, which is why checking it regularly matters.
Child Growth Chart Calculator UK — NHS Centile Chart
Free UK child growth chart calculator for ages 0–18 years. Enter your child's age, sex, height, and weight to see which centile band they fall into based on UK growth chart reference data (WHO Child Growth Standards for 0–5 years and UK90 reference data for 5–18 years). The UK growth chart uses nine centile lines — from the 0.4th to the 99.6th — to show the normal range of growth. Most healthy children grow between the 9th and 91st centile. Readings below the 2nd or above the 98th centile are flagged for GP review.