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 Much Mounjaro In Each Dose?
Mounjaro (tirzepatide) is available in five different strengths, with each dose delivered as a once-weekly injection via a KwikPen pre-filled device. The dose is measured in milligrams (mg), not millilitres (ml) — this is an important distinction, as the actual injection volume varies slightly depending on the strength. Understanding your Mounjaro dose is essential for tracking your treatment and knowing what to expect at each stage of your titration schedule. This guide explains the exact dosing amounts used in the UK and how the dose escalation works.
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 Doses And Injection Volumes
Mounjaro is prescribed by strength in milligrams (mg), not by injection volume. Each KwikPen contains four pre-filled doses and delivers a fixed amount of tirzepatide solution. The five available UK strengths are:
- 2.5 mg — starting dose, used weeks 1–4 of treatment
- 5 mg — first maintenance dose, used weeks 5–8+
- 7.5 mg — escalation dose, used weeks 9–12+
- 10 mg — escalation dose, used weeks 13–16+
- 12.5 mg — escalation dose, used weeks 17–20+
- 15 mg — maximum dose, used week 21 onwards
Each injection is 0.6 ml in volume regardless of strength — the difference is in the concentration of tirzepatide dissolved in that volume. Your prescriber will advise which dose is appropriate for you based on your response to treatment and individual health factors.
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.
Dose Titration And Escalation Schedule
Mounjaro uses a gradual dose escalation schedule to help your body adjust and minimise side effects. You must stay on each dose for a minimum of four weeks before increasing to the next strength — this allows time to assess how well you tolerate the medication and how your body responds. If you experience severe side effects, your prescriber may recommend staying on your current dose longer or moving up more slowly. Dose increases are not automatic; your prescriber will discuss whether escalation is appropriate for you at each review. Most people find their optimal dose somewhere between 5 mg and 15 mg, though some benefit from staying at lower doses.
- 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 Mounjaro mg and ml?
Mounjaro is measured in milligrams (mg) of the active ingredient tirzepatide. Each injection contains 0.6 ml of liquid, but the strength varies by dose. For example, a 5 mg dose and a 15 mg dose both deliver 0.6 ml, but the 15 mg dose contains more tirzepatide dissolved in that volume. You'll always inject the same volume, but the strength (mg) changes.
Does everyone start on 2.5 mg Mounjaro?
Yes, in the UK, everyone begins Mounjaro treatment with a 2.5 mg dose for the first four weeks. This is the standard starting dose regardless of body weight or BMI. After four weeks, your prescriber will review your progress and discuss whether to increase to 5 mg or remain at 2.5 mg based on your response and any side effects.
How quickly can Mounjaro doses be increased?
Each dose must be used for a minimum of four weeks before increasing to the next strength. This means the fastest typical escalation schedule is one dose increase every four weeks. However, if you experience side effects or prefer to progress more slowly, your prescriber may recommend staying at your current dose longer. There's no rush to reach the maximum dose.
What should I do if I miss a Mounjaro injection?
If you miss a dose within four days of when you were due to inject, take it as soon as you remember and continue your normal weekly schedule from there. If more than four days have passed, skip that dose and take your next dose on your normal scheduled day. Never take two doses within three days. Contact your prescriber or pharmacist for guidance if you're unsure.
Is Mounjaro available on the NHS in the UK?
Mounjaro is approved for weight management on the NHS, but access is through specialist tier 3 weight management services via referral from your GP — not standard GP prescription. NHS availability varies significantly by region and waiting lists can be lengthy. Many people access Mounjaro privately through online prescribing following a clinical assessment with a UK-licensed prescriber.
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.