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Dose calculator

Semaglutide dose calculator

Convert any Semaglutide dose into syringe units in real time, pre-filled with a 5 mg / 2 mL example.

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Draw on a U-100 syringe

10.0 units

Volume to draw

0.100 mL

Semaglutide is a once-a-week injection people use to lose weight and steady blood sugar. It mimics a gut hormone called GLP-1, which makes you feel full sooner and slows how fast your stomach empties. In the STEP-1 trial, adults without diabetes lost about 14.9% of their body weight over 68 weeks on the highest dose. This page covers the reconstitution math and how people log each weekly dose.

How the Semaglutide dose calculator works

This calculator answers a simple question: given the concentration of the Semaglutide solution already in your vial, how many syringe units does today's dose work out to? It is the second half of the reconstitution math — the first half locks in concentration, this one converts any dose mg or mcg into a clean unit count.

The formula is volume in mL equals dose mg divided by concentration mg/mL, then volume times one hundred to get units on a U-100 insulin syringe. With a 2.5 mg/mL Semaglutide solution and a 0.25 mg dose, the draw is 0.10 mL or about 10 units. Type any other dose and the unit count updates in real time — no spreadsheets, no guesswork.

Inputs that genuinely matter: concentration (which only changes when you reconstitute a new vial) and dose mass. Syringe type matters too, but only because U-100 vs U-40 changes the multiplier — almost every modern insulin syringe is U-100, which is why the math defaults to that. Edge cases worth flagging: switching from mcg to mg without checking the input unit, or carrying yesterday's unit count over to a new vial that was reconstituted with a different volume of BAC water.

Most people use this calculator at two moments: when titrating a dose up or down, and when prepping a single dose before injection. The output is meant to be checked against the syringe before drawing — read the markings, confirm the unit count, then draw. The calculator is fast precisely so you can do that check every time without it feeling like a chore.

How Semaglutide dosing is tracked

Weekly dosing is the default cadence for semaglutide because of its long half-life. Each injection is a small subcutaneous draw, almost always measured on a U-100 insulin syringe rather than a tuberculin syringe, because the volumes involved are very small.

Many semaglutide protocols start with a low weekly dose and escalate gradually over several weeks or months to reduce gastrointestinal side effects. Tracking that escalation accurately is one of the main reasons people move away from notes apps and toward a structured dose log: the cumulative pattern over months is what matters, and a pattern is hard to read from scattered text notes.

Skipped or delayed doses are recorded as deliberately as taken doses in most well-run logs, because gaps in the schedule meaningfully change the next week's planning. A vial-aware tracker also flags when the current vial is approaching empty so the next vial can be ordered in time, given semaglutide's typical four-to-six-week shipping windows.

When individuals plan to document a titration schedule observed in research studies, the core logging task becomes tracking the dose changes. A typical study protocol might involve starting at a low dose and stepping up that dose every four weeks. From a data-logging perspective, the calendar dates of these transitions are the most pivotal entries. Without a clear record of when the dose was increased from 0.25 mg to 0.5 mg, for example, it becomes impossible to later parse subjective or objective data and accurately attribute it to a specific dosage period. Therefore, a robust log must cleanly delineate each dosing chapter defined by the titration points.

Semaglutide mechanism in plain English

GLP-1 agonists bind to receptors in the pancreas and the brain. Activating the pancreatic receptor influences insulin and glucagon release in response to glucose; activating the central receptor influences appetite and gastric emptying. Semaglutide is engineered to resist enzymatic breakdown, which is what gives it its long half-life relative to native GLP-1.

Researchers and individuals tracking semaglutide are usually looking at weekly weight, hunger ratings, blood sugar readings, and side-effect notes alongside the dose log itself. Pairing those metrics with the dose history is how patterns become visible — for example, whether a dose change correlated with a change in hunger ratings the following week.

The ~7-day half-life mathematically dictates how Semaglutide accumulates in the body to reach a steady-state concentration. After the first weekly dose, approximately 50% of the peptide remains after seven days, at which point the second dose is administered. This new dose adds to the remaining concentration from the first. This stacking process continues with each subsequent weekly administration, with the total amount of the peptide present in the body incrementally increasing. After approximately four to five half-lives, or four to five weeks, the amount being eliminated over the week becomes roughly equal to the amount being added, establishing a concentration plateau known as steady state. This dynamic explains why logged observations during the first month may differ from those documented once this plateau is reached.

Common Semaglutide dose mistakes

  • Switching to a new vial of the same peptide and reusing the old unit count without re-running the calculation against the new vial's diluent volume.
  • Storing reconstituted semaglutide at room temperature for hours before refrigerating, especially after a travel day.
  • Dosing twice in the same week after forgetting whether the previous injection was Sunday or Monday — almost always a logging-gap problem, not a math problem.
  • Reading 0.25 mg as 25 units on the syringe regardless of vial concentration. The unit count is not fixed — it depends on the diluent volume.
  • Increasing the dose without writing down the date, then losing track of when the escalation began.
  • Confusing the multi-dose pen formulation marketed under brand names with the lyophilized powder vials common in the research market — they are not interchangeable preparations.
  • Failing to account for the cumulative effect of a long half-life, where each new weekly dose builds upon the concentration remaining from previous weeks.
  • Neglecting to log the precise calendar date of a dose titration, which makes it impossible to accurately correlate tracked metrics with the corresponding dose level.
  • Incorrectly calculating the new injection volume (mL or units) required after a dose increase, often by assuming the volume stays the same as the mass changes.

Frequently asked questions about Semaglutide dose

How is semaglutide reconstituted?
By adding a measured volume of bacteriostatic water to the lyophilized vial through the rubber stopper, then swirling — not shaking — until the powder fully dissolves into a clear solution. The exact diluent volume is up to the user; common choices for a 5 mg vial are 1, 2, or 3 mL.
How many units of semaglutide are in 0.25 mg?
It depends on the concentration of your vial. On a 5 mg vial reconstituted with 2 mL of bacteriostatic water, 0.25 mg is exactly 10 units on a U-100 insulin syringe. On a 5 mg vial reconstituted with 1 mL, the same dose is 5 units.
Why is semaglutide dosed weekly?
Because its half-life is approximately one week, which keeps blood plasma levels stable on a once-weekly injection schedule. That cadence is part of why semaglutide became attractive relative to earlier GLP-1 peptides that required daily dosing.
How long does a 5 mg vial of semaglutide last?
At a 0.25 mg weekly dose, a 5 mg vial provides 20 doses, which is 20 weeks of supply. The vial duration calculator will run the math for any combination of vial size, dose, and frequency.
Does semaglutide need to be refrigerated?
The lyophilized powder is generally stored refrigerated, and the reconstituted solution is kept refrigerated and used within roughly four to six weeks. Writing the reconstitution date on the vial helps prevent using a long-opened vial past its useful life.
Can semaglutide be split across multiple injections per week?
Some users do split a weekly dose into two smaller injections to smooth side effects, while others do not. The math still works the same way — the calculator handles any frequency you give it. Whether to split a dose is a decision to discuss with a healthcare professional, not something a calculator answers.
What is the difference between Ozempic and lyophilized semaglutide vials?
Ozempic and Wegovy are pharmaceutical formulations supplied in pre-filled multi-dose pens. Lyophilized vials of semaglutide that appear in the research market are powder-based and require reconstitution. The active peptide is the same molecule, but the products are not interchangeable preparations and should be tracked separately.
Why does the app store every semaglutide vial separately?
Because each vial may have been reconstituted with a different volume of bacteriostatic water, producing a different concentration. Tying every dose entry to its specific vial means the unit count on the syringe is always derived from that vial's real numbers, not from a remembered ratio that may no longer apply.
Why do tracked observations with Semaglutide often change during the first month?
Observations may change because of the peptide's long half-life of approximately seven days. Each weekly dose builds on top of what remains from previous weeks, causing a gradual increase in the body's total concentration. This accumulation phase continues until a 'steady state' is reached after about 4-5 weeks, at which point the peptide's level is more stable. The initial period reflects this build-up phase.
My research protocol involves increasing the dose every 4 weeks. Why is it critical to log these dates?
Logging the exact date of each dose increase, or titration, is the single most important action for data analysis. Without these dates, you cannot later determine which of your logged metrics or notes correspond to which dose. Your entire log for the first month at one dose would be mixed with data from the second month at a higher dose, making it impossible to observe dose-dependent patterns.
If my dose doubles from 0.25 mg to 0.5 mg, do I draw the same number of units on my syringe?
No, the volume drawn or unit count must also double. The concentration of your reconstituted vial is constant, so to double the dose mass, you must double the liquid volume. Following the standard numeric example, a 0.25 mg dose is 10 units (0.1 mL). Therefore, a 0.5 mg dose would require you to draw 20 units (0.2 mL) from the same vial to deliver the correct mass.

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