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
What's the Right Weight for Your Height and Age?
There's no single "perfect" weight for a given height and age — healthy weight ranges vary based on individual factors including muscle mass, bone density, and overall health. However, the NHS provides evidence-based guidance to help you determine whether your weight is in a healthy range for your height. Using BMI (Body Mass Index) as a screening tool, alongside other factors like waist circumference and age-related health conditions, you can assess whether your current weight supports good health. This guide explains how to find your personalised healthy weight range and why age matters in weight management.
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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 NHS Calculates Healthy Weight by Height
The NHS uses Body Mass Index (BMI) as the primary screening tool to determine healthy weight ranges for adults. BMI is calculated by dividing your weight in kilograms by your height in metres squared. For most UK adults, a healthy BMI falls between 18.5 and 24.9. Using this range, you can calculate the healthy weight range for any height.
For example: An adult who is 5ft 8in (1.73m) tall would have a healthy weight range of approximately 55–74 kg (8st 10lbs to 11st 10lbs). Use our free BMI calculator above to instantly check your personal BMI and see where your current weight falls.
However, BMI has important limitations — it does not distinguish between muscle and fat, so athletes may have a high BMI despite low body fat. For this reason, the NHS also recommends measuring waist circumference as a supplementary indicator of health risk. Men should aim for a waist below 94 cm (37in), and women below 80 cm (31.5in).
Clinically BackedWeight Loss
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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.
Does Age Affect Your Healthy Weight?
Age does influence healthy weight in two important ways. First, metabolic rate naturally decreases with age — you burn fewer calories at rest in your 60s than in your 20s, which means maintaining the same weight may require eating less or being more active. Second, body composition changes with age — older adults typically lose muscle mass and gain fat mass, even if their total weight stays the same.
However, the NHS BMI categories (18.5–24.9 for healthy weight) apply to all adults aged 18 and over. Some research suggests that slightly higher BMI in older age may be protective, but current NHS guidance does not adjust BMI thresholds by age. If you have health conditions or concerns about your weight as you age, your GP can provide personalised guidance. You can also track your progress over time using our free progress tracker to monitor trends rather than focusing on a single number.
- 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 a healthy weight range for 5ft 6in (168cm)?
For someone 5ft 6in tall, a healthy BMI range of 18.5–24.9 translates to approximately 52–69 kg (8st 2lbs to 10st 13lbs). Use our free weight converter to switch between kg, stone, and pounds, and our BMI calculator to check your exact BMI for your height.
Is healthy weight different for men and women?
No — the BMI categories and healthy weight ranges are the same for men and women of the same height. However, body composition differs; men typically have more muscle mass and women typically have higher body fat percentages at the same BMI. Waist circumference targets are also lower for women (below 80cm) than men (below 94cm).
Does ethnicity affect healthy weight ranges?
Yes — the NHS recommends lower BMI thresholds for people of South Asian, Chinese, Black African, and Black Caribbean heritage due to higher cardiovascular risk at lower BMI levels. For these groups, a healthy BMI is 18.5–22.9 rather than 18.5–24.9. Discuss this with your GP if relevant to you.
Should I aim for the middle of the healthy weight range or the lower end?
There's no evidence that one part of the healthy BMI range is better than another. Aim for a weight that feels sustainable, supports your energy levels and health conditions, and aligns with your GP's advice. Very restrictive dieting to reach the lower end can be counterproductive.
How can I work towards a healthier weight if I'm currently outside the healthy range?
The NHS recommends a sustainable rate of weight loss of 0.5–1 kg per week through a combination of reduced-calorie diet and increased physical activity. If you're significantly outside the healthy range, your GP can refer you to NHS weight management services or discuss prescription options if appropriate.
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.