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
Free tracker included with every download this week
Optimum Weight Calculator — Find Your Healthy Weight Range
An optimum weight calculator helps you determine the healthy weight range for your height using NHS-approved guidelines. Rather than aiming for a single "perfect" weight, the NHS recommends a healthy weight range based on BMI (body mass index). Your optimum weight depends on your height, age, sex, and muscle mass. Using a free weight management calculator alongside our BMI calculator makes it easy to understand what healthy weight looks like for you personally and track progress towards achievable goals.
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.
How to Calculate Your Healthy Weight Range
Your optimum weight is calculated using the BMI formula, which divides your weight in kilograms by your height in metres squared. The NHS defines a healthy BMI as 18.5 to 24.9 for most UK adults. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends a slightly lower range of 18.5 to 22.9.
To find your healthy weight range:
- Multiply your height in metres by itself to get height squared
- Multiply your desired BMI (18.5 for lower range, 24.9 for upper range) by your height squared
- The result is your optimum weight in kilograms
For example, if you're 1.73m tall (5ft 8in), your healthy weight range is approximately 55.4 kg (8st 10lbs) to 74.5 kg (11st 10lbs). Use our free BMI calculator above to instantly find your personal healthy weight range.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
Why Optimum Weight Matters for Health
Reaching your optimum weight reduces your risk of serious health conditions including type 2 diabetes, heart disease, high blood pressure, and certain cancers. Even losing 5 to 10% of your body weight can significantly improve blood sugar control, reduce joint strain, and boost energy levels.
However, optimum weight isn't one-size-fits-all. Muscle mass, bone density, and frame size affect where you sit within your healthy range. Someone very muscular may have a higher BMI but still be healthy. Your GP can give personalised advice about your individual optimum weight. Many people find that gradual, sustainable weight loss—alongside physical activity and balanced nutrition—works better than rapid weight change. Our free progress tracker helps you monitor your journey towards your healthy weight goal.
- 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 is the difference between my current weight and my optimum weight?
Your current weight minus your optimum weight (upper healthy BMI range) shows how much weight loss, if any, may benefit your health. However, only your GP can advise on whether weight loss is right for you personally. Factors like medical conditions, medications, age, and muscle mass all matter.
Can I use an optimum weight calculator to set my goal weight?
Yes. Use the BMI formula to find your healthy range, then set a realistic goal within that range. Most health professionals recommend losing no more than 0.5 to 1 kg per week for sustainable results. Our free progress tracker helps you monitor progress towards your goal.
Is optimum weight the same for men and women?
The BMI calculation is the same for all adults, but the healthy weight range depends only on your height, not your sex. However, average body composition differs between men and women, so where you feel healthiest within your range may vary. Your GP can give personalised guidance.
Does optimum weight change with age?
BMI categories remain the same throughout adulthood, but muscle mass naturally decreases with age. You may find your optimum weight shifts slightly as you get older. Strength training and regular physical activity help preserve muscle and support healthy weight management at any age.
What if I can't reach my optimum weight—should I be concerned?
Focus on gradual progress rather than perfection. Even small improvements in lifestyle—more activity, better nutrition, stress management—benefit your health regardless of reaching a specific number. Your GP can discuss realistic goals for your individual situation.
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.