Converting Wegovy units to mg: what the numbers on your pen actually mean

Step 1: Understand why "units" and "mg" are not interchangeable for Wegovy

The word "units" is deeply embedded in injectable medicine culture because of insulin. Insulin syringes are graduated in international units (IU), and people who self-inject insulin every day think naturally in that language. When GLP-1 medicines such as Wegovy arrived as weekly injections, some patients (and a surprising number of online forums) assumed the same unit framework applied. It does not.

Wegovy's pre-filled pen delivers a fixed, pre-set volume of solution that contains a precise milligram quantity of semaglutide. There is no dial, no graduation mark in units, nothing for a patient to adjust. You press the button; the pen does the rest. The dose is set at the point of manufacture for that specific pen strength. So when someone asks how many units are in a 2.4 mg Wegovy dose, the short answer is that the question does not have a meaningful answer in the Wegovy context, the correct figure to know is simply the milligram strength printed on the pen label. The NHS semaglutide medicines page explains the dose format in plain terms if you want a second reference point.

The confusion also arises because some compounding pharmacies in other countries have supplied semaglutide in vials drawn up with insulin syringes, where a unit-to-mg conversion does matter. Those products are not licensed in the UK. Licensed Wegovy in the UK is always the pre-filled pen, no conversion needed.

Step 2: Recognise the full licensed mg dose ladder in the UK

Knowing the milligram sequence helps you follow your own treatment without getting lost in unit arithmetic. The UK titration pathway for Wegovy, as described in the approved prescribing information, moves through set steps: 0.25 mg for the opening four weeks, then 0.5 mg, 1.0 mg, 1.7 mg, and 2.4 mg as the previous standard maintenance dose, each held for roughly four weeks before moving up, subject to your prescriber's decision. A higher 7.2 mg maintenance dose, approved by the MHRA in early 2026, is now also part of the licensed schedule, a dedicated single-dose 7.2 mg pen received regulatory sign-off in April 2026. Our Wegovy dose guide covers each step in more detail.

Every step up is a prescriber's call, not an automatic progression. The purpose of starting at 0.25 mg is to give the body time to adjust, most of the gastrointestinal side effects that put people off semaglutide are strongly dose-related, and beginning low genuinely reduces them. If you are wondering what 2.4 mg looks like in units for any comparison purpose, there is a dedicated explanation at how many units is 2.4 mg of Wegovy, though the conclusion is the same: for the licensed UK pen, the mg figure on the label is the one that counts.

It is worth pausing here to acknowledge that working through a dose schedule while also deciphering different measurement systems is genuinely confusing, especially if you are new to injectable medicines. You are not unusual for finding this unclear.

Step 3: Know when a unit-to-mg conversion actually matters, and when it does not

There are narrow situations where converting between units and micrograms or milligrams has clinical relevance. If a prescriber or pharmacist needs to compare semaglutide concentrations across different formulations (for example, the oral Wegovy tablet versus the injection) they work in micrograms or milligrams. The concentration of semaglutide in Wegovy injection solution is fixed per pen strength, so there is nothing for a patient to calculate.

Where the conversion question most often has real-world teeth is in error-prevention. A patient who has moved from insulin injections to Wegovy, or who is managing both simultaneously, needs to be crystal clear that the Wegovy pen is not drawn up in units and that insulin syringe graduations must never be applied to it. The semaglutide dose in units page addresses this directly for people who need the fuller picture. Related dose-specific questions are answered at 10 units to mg semaglutide and 30 units to mg semaglutide for anyone comparing across formulations.

For cost context, the Wegovy pricing page sets out what private treatment involves and what a legitimate price should cover, which is useful background if you are weighing your options. A broader look at the medicine itself is on our Wegovy overview.

The British National Formulary's semaglutide entry is the professional reference our prescribers use for dosing detail, it confirms that semaglutide strengths for weight management are always expressed in mg, not units.

Step 4: Getting the dose question answered properly for your situation

Reading about dose schedules is a reasonable starting point, but the only person who can tell you which milligram strength is appropriate for you, and when to move to the next one, is a prescriber who has reviewed your health history. Dose decisions depend on how you tolerated the previous step, your current weight, any other medicines you take, and factors that no article can account for. If you have questions about your own dose or want to start Wegovy through a regulated UK pharmacy, speaking to our prescribers is the straightforward next step, there is no charge for the consultation.