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 — BMI Checker (NHS Categories)
Free BMI calculator for UK adults. Calculate your body mass index (BMI) and check whether you are a healthy weight. Enter your height and weight, and your BMI result appears in seconds, along with your NHS weight category and the healthy weight range for your height. Body mass index (BMI) is a useful long term guide to your overall health, but it is only one piece of the picture. It does not measure body fat or body composition directly, so muscle mass, age, and body shape all affect what your BMI result really means.
PopularSleep Calculator UK — Best Bedtime & Wake Up Times
Find the best times to wake up or fall asleep based on 90-minute sleep cycles, so you wake feeling refreshed instead of groggy. Enter your alarm time and this sleep cycle calculator counts back through complete cycles to show your ideal bedtimes — or work forwards from your bedtime to find the best wake-up times.
PopularUK Calorie Calculator — TDEE & Daily Calories
Free UK calorie and TDEE calculator. TDEE stands for Total Daily Energy Expenditure — the total amount of energy your body burns in a day. This tool first estimates your basal metabolic rate (BMR) using the Mifflin-St Jeor formula, then applies your activity level to give your full TDEE and personalised calorie targets. Use it to set a clear starting point for weight loss, maintenance, muscle gain, or general weight management, and get a precise daily calorie figure in seconds.
TDEE Calculator — Total Daily Energy Expenditure
Free TDEE calculator — find your Total Daily Energy Expenditure and exact daily calorie target for weight loss, maintenance, or muscle gain. Uses the Mifflin-St Jeor formula (the most accurate BMR method) adjusted for your activity level. Unlike a generic calorie guide, this TDEE calculator gives you a personalised number based on your body and lifestyle. The NHS recommends 2,000–2,500 calories as a general figure — your actual TDEE may be significantly higher or lower depending on your age, weight, and how active you are.
How Much Water to Drink a Day Calculator — UK Water Intake Tool
Free water intake calculator. Find out how much water you should drink each day, based on your weight and activity level. You get a recommended daily amount in litres and cups, using NHS hydration guidelines. Staying hydrated helps your body work properly. It regulates your temperature, supports weight loss, and boosts energy and concentration. If you exercise, or are pregnant or breastfeeding, you need to drink more. Your body loses water all day through breathing, sweating, and urination, so keep a bottle nearby and sip regularly.
Blood Pressure Checker — NHS Blood Pressure Chart UK
Check any blood pressure reading against the NHS categories in seconds. Enter your systolic and diastolic numbers to see which band you fall into — low, ideal, pre-high, or hypertension stage 1 or 2. The full NHS blood pressure chart is included, so you can see exactly where your reading sits. High blood pressure (hypertension) affects around 1 in 3 UK adults and is a leading risk factor for heart attack and stroke. Most people with it have no symptoms. That is why a regular blood pressure test matters — at home, at a pharmacy, or at your GP surgery.
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.