GLP-1 Dose Conversion Chart: Why There Is No Exact Match (October 2026)

01 · The core answer

Is there a GLP-1 dose conversion chart you can trust?

No chart can honestly tell you that a given Wegovy dose equals a given Mounjaro dose. The medicines contain different active ingredients, work through different receptors and have their own licensed ladders. Anything that claims an exact equivalent is presenting a guess as a fact.

What you can do is compare the shape of each ladder: how many steps it has, how often you move up, and where the licensed maximum sits. The table shows this. It is a map of the ladders, not a set of equivalents.

Read across a row, never down a column. The Wegovy ladder tops out at 2.4mg and the Mounjaro ladder at 15mg, but those numbers are not comparable. They describe different molecules and different pens.

02 · Your decision

What should you do if you are switching GLP-1 medicines?

Switching is a prescriber decision, not a calculation you do yourself. Tell the prescriber which medicine you are on, your current dose, how long you have taken it, how well you have tolerated it and why you want to change. Those details matter far more than any conversion figure.

If you are moving onto Mounjaro, there is no licensed direct conversion: your prescriber starts you at a dose they judge appropriate, often the 2.5mg starting dose, sometimes adjusted based on your history. ¹ Your prescriber may then move you up at a pace that suits your tolerance, with at least 4 weeks on each dose.

The reasons behind this are practical. A higher dose of one medicine does not mean your body has built tolerance to a different medicine. Nausea, fullness and reduced appetite are the usual early effects of this drug class, and starting low gives the new medicine a chance to settle in. We cover the detail in our guides to the Ozempic to Mounjaro doses and the Wegovy to Mounjaro switch, and for the opposite direction the Mounjaro to Wegovy guide.

The Mounjaro pen 2.5mg starting pen costs £169.99 per month at the standard price, and new customers save £40 on their first order with code FIRST40. An automatic £25 reorder discount applies to every future order (code DOSE25). Consultation is free, and the prescriber reviewing it is GPhC-registered.

If you would rather compare ladders more broadly before deciding, see the dose comparison chart and the dosage chart, and the weight loss clinic explains the wider treatment pathway.

Finally, resist the urge to pick your own starting dose. The safest approach is to describe your history honestly, let a prescriber decide, and move up only when you are ready.

03 · Why milligrams do not convert

Why milligrams do not convert between GLP-1 medicines

Milligrams do not convert because a milligram measures weight of a substance, not strength of effect. A milligram of one active ingredient can do far more or far less than a milligram of another, depending on how tightly it binds, how long it lasts and which receptors it reaches.

Mounjaro is the brand name for tirzepatide, a once-weekly injectable prescription medicine made by Eli Lilly. ¹ Tirzepatide is the first treatment of its kind to activate two natural gut-hormone receptors at once: GIP and GLP-1. ¹ Semaglutide, the ingredient in Wegovy and Ozempic, is a single-action GLP-1 medicine. Different targets mean different dose-response behaviour, so there is no fixed exchange rate to calculate.

Duration matters too. Tirzepatide has a half-life of about five days, so after a final dose it takes roughly 4–5 weeks to clear the system — there is no way to speed this up, and nothing needs doing while it clears. ¹ A medicine that is cleared faster or slower than another behaves differently on the same weekly schedule, even if the numbers on the pen look similar.

Then there is frequency. Wegovy and Mounjaro are weekly, while liraglutide is daily. A daily dose cannot be turned into a weekly one by multiplying, because the body is exposed to the drug in a completely different pattern across the week.

Finally, each pen is engineered around its own dosing. ¹³ The device, the concentration and the ladder are designed as a unit. Transplanting a number from a different device ignores all of that.

That is why a trustworthy chart shows ladders and then sends you to a prescriber. If you want to see how the steps compare visually, our dosing calculator page explains what such tools can and cannot do.

In short, the maths looks tidy but the pharmacology is not. Equivalence tables that pretend otherwise cause confusion, which is a good reason to involve a clinician when you change medicine.

04 · The Mounjaro dose ladder

The Mounjaro dose ladder in detail

The Mounjaro ladder has six strengths, and every patient climbs it from the bottom. The KwikPen comes in six strengths: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg. ¹ Each pen contains four weekly doses.

Everyone starts Mounjaro on 2.5mg once a week. This starting dose is about letting your body adjust, not about weight loss itself. After at least 4 weeks the dose increases to 5mg, and can then step up by 2.5mg at a minimum of 4-week intervals (7.5mg, 10mg, 12.5mg) up to a maximum of 15mg weekly, depending on how you respond and tolerate it. ¹

Many people settle at a maintenance dose of 5mg, 10mg or 15mg — higher is not automatically better, and your prescriber will guide the right pace. ¹ This is worth remembering when you look at any conversion chart. The goal is not to reach the top of a ladder; it is to find the dose that works for you with tolerable effects.

The sensible reading of the ladder is as a menu of options, not a staircase you must finish. Some people feel well and respond on a middle dose, and staying there is a perfectly good outcome.

Injecting and timing

Mounjaro is injected under the skin once a week, on the same day each week, at any time of day, with or without food. ¹³ Licensed injection sites are the stomach area (at least 5cm from the belly button), the front of the thigh, or the back of the upper arm if someone else gives the injection. Rotate the site with each dose.

There is no best time of day. What matters is the same day each week, so pick a day and time you will remember.

Missed doses and day changes

If you miss a dose, take it as soon as you can within 4 days (96 hours) of the scheduled time, then carry on with your usual day. If more than 4 days have passed, skip the missed dose entirely and take the next one on your normal day — never take two doses within 3 days of each other. ¹

You can change your weekly injection day if needed, as long as at least 3 days (72 hours) have passed since your last dose. ¹

Our single dose guide explains what one pen dose means in practice, which is useful if you are trying to relate a pen strength to the number on a chart.

05 · Wegovy and liraglutide ladders

The Wegovy and liraglutide ladders for comparison

Wegovy has five pen strengths and finishes at a licensed maintenance dose of 2.4mg, which starts from week 17. The 2.4mg dose is the licensed maintenance dose for weight management. ¹⁸

Notice what is different from Mounjaro. Wegovy has five pen strengths in uneven increments, while Mounjaro rises in even steps of 2.5mg. Mounjaro offers a range of possible maintenance doses and lets your prescriber set the pace.

This is why people who say they are "on the top Wegovy dose" cannot simply be assigned a Mounjaro dose. The top of one ladder has no matching rung on the other. The number 2.4mg tells you where you are on Wegovy and nothing more.

Where liraglutide fits

Liraglutide (Saxenda, and products such as Erly) is supplied at a concentration of 6mg per millilitre, and it is a daily injection, unlike once-weekly Mounjaro and Wegovy. That one fact is enough to show why a conversion chart is misleading.

If you are on liraglutide and thinking of changing, your prescriber can advise on how to proceed, and the information they need is your current dose, how long you have taken it and how you have tolerated it.

Tablet forms

There are also tablet versions of GLP-1 medicines, and they have their own dose schedules, which are separate again. For current Wegovy options, see the Wegovy pen page, and check the product pages for what is available.

The takeaway is simple. Look at each ladder on its own terms, understand its pace and its ceiling, and use that understanding to have a better conversation with a prescriber rather than to do your own conversion.

06 · Switching from Wegovy or Ozempic

Switching from Wegovy or Ozempic to Mounjaro

Moving from semaglutide to tirzepatide means joining the Mounjaro ladder at its licensed starting point, with your prescriber deciding the pace. Everyone starts Mounjaro on 2.5mg once a week. There is no licensed direct conversion between semaglutide and tirzepatide: typically the previous medicine is stopped, a washout interval observed, and Mounjaro started at a dose your prescriber judges appropriate — often the 2.5mg starting dose, sometimes adjusted based on your history. Ozempic is semaglutide licensed for type 2 diabetes — it is not a UK weight-loss medicine, and prescribing it privately for weight loss is off-label.

Why not jump higher? Because the two medicines are not interchangeable at the molecular level, and because the early effects of this drug class are dose-related. Mild nausea, altered appetite and tiredness in the first days after each injection are the commonest early effects and usually settle. ¹ Starting low is the sensible way to meet them.

The first weeks are about adjustment, and experiences differ widely: some people notice appetite change and early loss in week one, others feel little until a higher dose, and both are normal. Early loss includes water weight, so the trend over weeks matters more than any single weigh-in. ¹

What to tell the prescriber

A good consultation covers the following points:

• Which semaglutide product you take, and your current dose on its ladder.
• How long you have been on that dose, and whether you ever paused.
• The side effects you have had, and how severe they were.
• Your reason for switching, such as a plateau or tolerability.
• Any other medicines you take, including insulin or contraception.

On medicines: oral contraceptives may be less well absorbed because Mounjaro slows stomach emptying, and insulin or sulfonylurea doses may need adjusting because of the risk of low blood sugar. The SmPC advises switching to a non-oral method, or adding a barrier method (such as condoms), for 4 weeks after starting Mounjaro and for 4 weeks after each dose increase.¹ Say so in the consultation so the prescriber can plan around it. Mounjaro must not be used during pregnancy, and it should be stopped at least one month before trying to conceive. If you become pregnant during treatment, stop the medicine and tell your prescriber promptly.

Practical pathway

If you are weighing up the switch, we have a step-by-step guide for the Ozempic to Mounjaro switch.

Switching at the top of the Mounjaro range is not something to plan on your own. Describe your history, accept the licensed start, and let your prescriber set the pace.

07 · Switching from Mounjaro to Wegovy

Switching from Mounjaro to Wegovy and stopping safely

Going from Mounjaro to Wegovy follows the same principle in reverse: you join the Wegovy ladder as your prescriber directs, not at a figure calculated from your Mounjaro dose. The Wegovy pens are 0.25mg, 0.5mg, 1mg, 1.7mg and 2.4mg once weekly, with steps after at least four weeks. ¹⁸

Reasons for switching in this direction vary. Some people prefer a different product for personal, practical or tolerability reasons. Whatever the reason, the prescriber needs your full history, including your last Mounjaro dose and when you took it.

What clearance means for timing

Because tirzepatide stays in the body for some time, the previous medicine is still present when you start the next. Tirzepatide has a half-life of about five days, so after a final dose it takes roughly 4–5 weeks to clear the system — there is no way to speed this up, and nothing needs doing while it clears. ¹

That clearance is one reason a prescriber thinks carefully about timing and starting dose when you change medicine.

Do not improvise

Do not alter doses or use part doses to bridge a switch: altering doses outside the licence means unknown dosing accuracy and no safety data. ¹³

Where to read more

For the direction-specific detail, our Mounjaro to Wegovy chart page sets out what to discuss and what to expect. Pair it with the cost comparison chart if price is part of your decision.

Whatever you decide, keep your prescriber in the loop. A planned change with a clear starting dose is far smoother than an improvised one, and the aftercare from our prescribing team includes ongoing monthly reviews.

08 · Why online charts mislead

Why online conversion charts and calculators can mislead

Most online charts mislead because they present a rough comparison as a rule. A table with tidy rows of matching doses looks authoritative, but it usually reflects someone's judgement about approximate effect rather than a regulated equivalence. The licensed product information for each medicine does not map its steps onto another medicine's steps.

There are several common traps. The first is false precision: a chart that gives a single "equivalent" dose hides the fact that people vary widely in response. The second is mixing frequencies, where a daily dose is placed next to a weekly one. The third is mixing products, where a tablet is shown level with an injection. Each of these makes a chart look neater and less true.

The pen dial is not a click counter

¹³ Advice that tells you to dial a certain number of clicks to "convert" a dose ignores how the pen actually works and risks an inaccurate injection.

What a good tool does

A useful tool, such as the dosing calculator explainer, shows you the licensed steps and explains what to ask. It does not tell you what to inject. If a site claims to calculate your exact new dose from your old one, treat that as a warning sign.

Be especially wary of sellers offering to supply a medicine without a consultation or prescription. That is unsafe whatever dose they quote. Mounjaro is a prescription-only medicine, supplied only after an online consultation reviewed by a GPhC-registered prescriber. ¹

Our approach is to give you honest ladders, explain the reasoning, and let a clinician set the dose. That may feel less satisfying than a one-line answer, but it is the version that protects you.

09 · Results and realistic pace

What results to expect after a switch

Expect a gradual process measured in months, not days. Weight loss on Mounjaro is gradual by design. The first weeks on 2.5mg are an adjustment phase and losses are usually modest; most measurable progress builds from 5mg onward, month by month. ¹ Trials measured results at 72 weeks, so think in months and judge progress by trend rather than individual weigh-ins.

For context, here is the headline trial. In the SURMOUNT-1 trial of 2,539 adults, people taking tirzepatide alongside diet and exercise lost on average 15% of their body weight on 5mg, 19.5% on 10mg and 20.9% on 15mg over 72 weeks, compared with 3.1% with lifestyle changes alone. ² These are trial averages — individual results vary, and treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them.

At 72 weeks, 85% of participants on 5mg, 89% on 10mg and 91% on 15mg had lost at least 5% of their body weight. Half of participants on 10mg and 57% on 15mg lost at least 20% of their body weight. ²

As a worked example only, for someone starting at 100 kg, 20.9% is about 21 kg. That is simple arithmetic on a trial average, not a prediction of your own result, which may be higher or lower.

What this means when switching

These figures describe people who started Mounjaro in a trial. They do not tell you how a switch from another medicine will go. A different trial of a different medicine had different people, different methods and different aims.

If you switch, expect the first weeks on 2.5mg to feel like an adjustment, even if you have lost weight before. Appetite changes may differ from what you felt on your previous medicine.

Review points

Treatment response is reviewed by your prescriber: if you have lost less than 5% of your starting weight after 6 months on the highest dose you can tolerate, your prescriber will discuss whether continuing or stopping is right for you. ¹

That review is the proper place to talk about whether a dose change is worthwhile, rather than a chart. Your prescriber can see your actual trend and tolerability and can decide on a pace with you.

10 · Cost, NHS access and ordering

Cost, NHS access and how ordering works

Cost depends on the dose you are prescribed, which is another reason to settle the dose before you plan a budget. The standard price of one pen (four weeks) at each strength shows on the Mounjaro product page, where the 2.5mg pen is £169.99 per month and the 5mg pen is £218.99 per month. The 15mg pen is £329.99 per month. All six doses are in stock, and prices were checked 10 October 2026.

New customers save £40 on their first order at any dose with code FIRST40, and an automatic £25 reorder discount applies to every future order (code DOSE25). If you step up after 4 weeks on each dose, your first four pens (2.5mg to 10mg) cost £959.96 at standard prices; a new customer's first order is £40 less and every later order £25 less. A first year costs £2,711.88 if you stay on 5mg after your 2.5mg starting pen, up to £3,599.88 if you step up through every dose to 15mg, again before discounts. For a comparison across providers, see the cost comparison chart.

NHS versus private

Mounjaro is available on the NHS, but access is being phased in over several years. ⁴ NICE recommends it for adults with a BMI of at least 35 plus at least one weight-related condition, and the NHS primary-care rollout began in June 2025 with the highest-need groups first (initially BMI 40+ with four or more qualifying conditions). ⁴⁶ Full rollout is expected to take years, which is why many people who meet the licensed criteria choose regulated private treatment rather than waiting.

NHS access to Wegovy runs through specialist weight-management services; ask your GP.

How ordering works

Ordering is straightforward, and the price shown is the price paid:

• Free online consultation. A short health questionnaire, no charge, no obligation.
• Prescriber review. Reviewed by a GPhC-registered prescriber, not a scoring script. Payment is taken when you place the order; if the prescriber decides the treatment is not suitable, the order is refunded automatically in full.
• Dispensing and delivery. Dispensed by our registered pharmacy, with same-day dispatch when ordered by 3pm and free next-day tracked delivery in temperature-controlled packaging. Saturday delivery is £14.99.

Mounjaro comes via official LillyDirect supply, direct from Eli Lilly's UK distribution, so the KwikPens are genuine. Needles, a sharps bin and injection guidance are included with every order. Repeat orders re-check suitability, with no auto-shipping and no subscriptions, and our team provides ongoing monthly reviews and side-effect support.

Storage once it arrives

Keep Mounjaro pens in a fridge at 2–8°C and never freeze them. Once in use, a pen can be kept out of the fridge at a temperature not above 30°C for up to 30 days after first use — useful for short trips — and must then be thrown away. Do not use a pen that has been above 30°C or has been frozen. ¹

Mounjaro (tirzepatide) is a prescription-only medicine, used alongside a reduced-calorie diet and increased physical activity. Individual results vary. This page is information, not a substitute for medical advice.