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
Mounjaro Dosage Levels Explained
Mounjaro (tirzepatide) is prescribed in the UK as a once-weekly injectable dose that starts low and increases gradually over time. This guide explains all Mounjaro dosage levels, how the dose titration schedule works, and what to expect at each stage. Each dose is delivered via a pre-filled KwikPen device. Understanding your Mounjaro dose helps you know what to expect as your prescriber adjusts your treatment based on your individual response and tolerance.
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.
Mounjaro Dosage Schedule and Titration
Mounjaro is started at the lowest dose and increased gradually every 4 weeks until you reach your maintenance or target dose. This approach minimises side effects and allows your body to adjust. Here is the UK dosage schedule:
- Weeks 1–4: 2.5 mg — Starting dose, helps your body adjust
- Weeks 5–8: 5 mg — First maintenance dose, commonly used
- Weeks 9–12: 7.5 mg — Escalation dose if needed
- Weeks 13–16: 10 mg — Further escalation
- Weeks 17–20: 12.5 mg — Penultimate dose
- Week 21+: 15 mg — Maximum licensed dose
Your prescriber will assess your response at each stage. Some people reach their target dose earlier, while others may stay at a lower dose if it's working well. You must stay on each dose for at least 4 weeks before increasing, and the minimum time between doses is 72 hours (3 days).
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.
Expected Weight Loss by Mounjaro Dose
Clinical trial data from the SURMOUNT-1 study shows average weight loss varies by dose level. On 5 mg, participants lost approximately 15% of their body weight over 72 weeks. At 10 mg, loss increased to approximately 19.5%, and at the maximum 15 mg dose, approximately clinically studied weight loss was observed. However, individual results vary significantly — some people may lose more or less than these averages. Try our free GLP-1 weight loss calculator above to estimate potential results at different doses based on your starting weight. Weight loss is achieved alongside a reduced-calorie diet and increased physical activity, not from the medication alone.
- 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 starting dose of Mounjaro?
The starting dose is 2.5 mg, injected once weekly for weeks 1–4. This allows your body to adjust and helps minimise nausea and other side effects. After 4 weeks, your prescriber will usually increase you to 5 mg unless side effects require a slower approach.
Can I skip dose increases or stay on a lower dose?
Yes. If you're seeing good results and tolerating the medication well at a lower dose, your prescriber may keep you there. You don't need to reach the maximum 15 mg dose. The goal is to find the dose that works best for you with manageable side effects.
What happens if I miss a Mounjaro injection?
If you miss a dose within 4 days of when you should have taken it, inject as soon as you remember, then continue your normal schedule. If more than 4 days have passed, skip that dose and take your next dose on your usual day. Never double-dose.
How long does it take to see weight loss results on Mounjaro?
Most people begin noticing appetite changes within 1–2 weeks, but significant weight loss typically becomes evident after 4–8 weeks. The trial data was collected over 72 weeks, so sustained results take time. Use our progress tracker to log your weight weekly and see trends over months.
Is Mounjaro dosage the same for everyone?
No. Your prescriber will personalise your dose based on your response, tolerance, weight loss progress, and any side effects. Some people plateau at 5 or 10 mg, while others benefit from reaching 15 mg. Your GP or specialist will guide this decision.
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.