The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
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Calculate Your BMR in the UK — A Practical Health Guide
Your basal metabolic rate (BMR) is the number of calories your body burns at rest just to maintain essential functions like breathing, circulation, and cell production. Calculating your BMR is a useful step in understanding your personal energy needs and can inform weight management decisions. In the UK, BMR calculations use metric measurements and are aligned with NHS health guidance. Knowing your BMR helps you understand how many calories you need daily and supports informed choices about diet and activity levels.
10,000+ calculations today · NHS-aligned thresholds · 100% free
Calculate Your BMI Instantly
Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
What Is BMR and Why Does It Matter?
BMR (basal metabolic rate) is the minimum number of calories your body needs each day to function at rest. It accounts for energy used by your heart, lungs, brain, and all other vital organs. Your total daily energy expenditure (TDEE) is your BMR multiplied by your activity level — so understanding your BMR is the foundation for calculating how many calories you actually burn in a day.
Several factors affect your BMR:
- Age: BMR decreases by approximately 2% per decade after age 20
- Sex: Men typically have higher BMR than women due to greater muscle mass
- Body composition: Muscle tissue burns more calories at rest than fat tissue
- Height and weight: Larger bodies require more energy to maintain
- Genetics: Some people naturally have faster or slower metabolisms
- Medical conditions: Thyroid disorders, hormonal changes, and other conditions can affect BMR
BMR is different from RMR (resting metabolic rate), which is slightly higher and includes light daily activities.
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How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
How to Calculate Your BMR — Two Common Methods
The Mifflin-St Jeor equation is the most accurate method used by NHS practitioners and nutritionists in the UK:
For men: (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5
For women: (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161
The older Harris-Benedict equation is also used but tends to overestimate slightly. Once you have your BMR, multiply by your activity factor: sedentary (×1.2), lightly active (×1.375), moderately active (×1.55), very active (×1.725), or extremely active (×1.9) to find your total daily calorie needs. Use our free BMI calculator to assess your healthy weight range alongside your BMR calculation for a complete picture of your metabolic health.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
What's the difference between BMR and TDEE?
BMR is the calories burned at complete rest. TDEE (total daily energy expenditure) is your BMR multiplied by your activity level — so it includes all movement, exercise, and daily activities. TDEE is what you need for weight management planning.
Does BMR affect weight loss?
Yes. Your BMR determines your baseline calorie needs. To lose weight, you need a calorie deficit. Knowing your BMR helps you calculate safe, sustainable deficit targets. The NHS recommends a deficit of around 500 kcal/day for approximately 0.5 kg weekly loss.
Can I increase my BMR?
Yes, partly. Building muscle through strength training increases BMR because muscle tissue burns more calories at rest than fat. Adequate protein intake, regular activity, good sleep, and managing stress also support healthy metabolism, though genetics play a significant role.
Is BMR the same for everyone my age and weight?
No. Two people of identical age, weight, and height can have different BMRs due to genetics, body composition, medical conditions, and hormonal factors. This is why BMR is a personal calculation, not a one-size-fits-all figure.
Should I use BMR for weight loss planning?
BMR is useful context, but for weight loss, focus on TDEE (your actual daily burn including activity). Most healthy weight loss combines dietary changes with increased physical activity. Your GP or a registered dietitian can provide personalised guidance aligned with NHS weight management principles.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.