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
How Many Clicks For 3.75 On A 5mg Wegovy Pen?
A 5mg Wegovy pen does not have pre-marked click stops for 3.75mg — the pen is only designed to deliver either 0mg (no injection) or the full 5mg dose. This is important UK health information for anyone using semaglutide for weight management. If your prescriber has recommended 3.75mg as part of your dosing schedule, you would typically use a different pen strength or receive specific guidance on dose timing. Always follow the exact instructions provided by your GP or prescriber, and refer to the patient information leaflet included with your medication.
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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.
Understanding Wegovy Pen Dose Increments
Wegovy pens are designed with fixed dose increments, not adjustable click mechanisms. The 5mg pen delivers only the complete 5mg dose — there is no way to manually select 3.75mg by counting clicks.
- Wegovy comes in four different pen strengths: 0.25mg, 0.5mg, 1mg, 1.7mg, and 2.4mg
- Each pen is pre-programmed to deliver its full stated dose with each injection
- Doses of 3.75mg fall between the 2.4mg and 5mg range, so your prescriber would not typically use a standard 5mg pen for this amount
If you have been prescribed 3.75mg as part of your NHS guidance or weight management plan, your GP should have issued a different pen strength or explained your specific dosing schedule. Attempting to estimate partial doses by guessing clicks could result in an incorrect dose, so always use the pen strength your prescriber has specified.
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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.
What To Do If You're Unsure About Your Dose
If you have received a 5mg pen but your prescription states 3.75mg, contact your prescriber or pharmacist immediately — do not attempt to guess the dose. Your NHS GP, specialist weight management service, or private prescriber can clarify whether you need a different pen strength or if your dosing schedule needs adjustment.
For accurate information about your weight management journey, you can use our free GLP-1 weight loss calculator to understand projected outcomes at different doses, and the BMI calculator to track your baseline and progress. Always keep your prescriber informed of any questions about your medication, as semaglutide dosing is individualised based on your health profile and weight loss response.
- 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.
Can you use part of a 5mg Wegovy pen?
No. Wegovy pens are pre-programmed to deliver their full dose with each injection. A 5mg pen cannot be adjusted to deliver 3.75mg. If your prescriber recommends 3.75mg, you would need a different pen strength or a specific dosing schedule using multiple pen types.
What Wegovy pen strengths are available in the UK?
Wegovy is available in five strengths: 0.25mg, 0.5mg, 1mg, 1.7mg, and 2.4mg. These are used during the dose escalation phase. Higher doses like 3.75mg would require combining doses or using a different dosing approach decided by your prescriber.
Who should I contact if my Wegovy dose seems wrong?
Contact your GP, NHS specialist weight management service, or the private prescriber who issued your prescription. Never adjust your dose yourself. Your prescriber can clarify your dosing schedule and ensure you have the correct pen strength.
Is Wegovy the same as Ozempic?
Both contain semaglutide, but Wegovy is licensed in the UK specifically for weight management, whilst Ozempic is approved for type 2 diabetes. They are not the same product — always use the medication your prescriber has specified.
How does Wegovy help with weight management?
Wegovy is a GLP-1 receptor agonist that may help reduce appetite and food cravings, supporting you to feel fuller after smaller meals. Clinical trials showed an average weight loss of approximately 15% body weight. Results vary by individual and work best alongside a reduced-calorie diet and increased physical activity.
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.