Tool
Semaglutide half-life calculator
Preset to semaglutide's approximately 1-week half-life from the FDA label. See relative level over repeated doses, the accumulation ratio, and approximately how long steady state takes - adjust the interval to anything you want to model.
Guides:semaglutide dosage (FDA schedules)·semaglutide overview
Your numbers
Half-life approximately 1 week, per WEGOVY (semaglutide) prescribing information, section 12.3 Pharmacokinetics (DailyMed, National Library of Medicine). Dosing interval below is still yours to set.
How long the level takes to fall by half. Not a dose recommendation - a physical property of the compound and the person taking it.
How often an equal dose is repeated. This tool does not suggest a schedule - it only draws what a given interval would produce.
Level over repeated doses
Accumulation ratio
2x
steady-state peak ÷ one dose's own peak
~90% steady state
4
doses in, ≈558.1 h (23.25 d)
Half-life 168 h (7 d). Dosed every 168 h (7 d). Steady state (about 90%) is reached after roughly 4 doses, around 558.1 h (23.25 d) after the first dose. Accumulation ratio 2x: at steady state, the peak level after each dose is about 2 times one dose's own peak, and the trough between doses is about 1 times it.
- Elimination rate constant (k)
- 0.0041 per hour
- Steady-state peak(right after each dose)
- 2x
- Steady-state trough(right before the next dose)
- 1x
- ≈97% of steady state
- 849.9 h (35.41 d)
Accumulation ratio = 1 ÷ (1 − e^(−k·τ)), where k = ln(2) ÷ half-life and τ is the dosing interval. Time to steady state depends only on half-life, not on the interval - the same reason a rule of thumb like "about 4-5 half-lives" gets taught regardless of how often a dose repeats.
Half-life preset from WEGOVY (semaglutide) prescribing information, section 12.3 Pharmacokinetics, DailyMed, National Library of Medicine -source. Results update in the address bar so a calculation is shareable; nothing is stored.
The actual semaglutide dose
Half-life explains how a dose behaves once it's in the body - it says nothing about how large that dose should be. The schedule that has gone through FDA review differs by brand: Wegovy titrates over 16 weeks to a 2.4 mg (or 1.7 mg) weekly maintenance dose, and Ozempic titrates to a maintenance dose between 0.5 mg and 2 mg weekly, both starting at 0.25 mg. That full schedule is on thesemaglutide dosage page, and background on the drug itself is on themain semaglutide page. For reconstitution arithmetic (vial size, diluent, draw volume), see thesemaglutide dosage calculator.
Common questions
What is the half-life of semaglutide?
Approximately 1 week, per the Pharmacokinetics section of the Wegovy FDA prescribing information. This tool is preset to that figure so the chart below shows semaglutide's own accumulation curve, not a generic example.
Why is semaglutide dosed once weekly?
A roughly 1-week half-life matched to a 7-day (once-weekly) dosing interval means each dose has fallen by about half before the next one arrives - a pace the label's once-weekly schedule is built around. The chart above plots exactly that relationship for any interval you choose.
How long does it take semaglutide to reach steady state?
Using the standard first-order model, roughly 3.3 half-lives to reach 90% of steady state - about 3-4 weeks at a 1-week half-life - and around 5 half-lives (about 5 weeks) to reach 97%. That figure comes from the half-life alone and does not depend on the once-weekly interval or on where someone is in dose titration.
Does the half-life differ between Wegovy and Ozempic?
No. Wegovy and Ozempic are the same semaglutide molecule and injection, approved for different indications (weight management and type 2 diabetes respectively), and both labels report the same approximately one-week half-life.
Does a compounded semaglutide vial have the same half-life?
Half-life is a property of the semaglutide molecule's own elimination, not of how a specific product is packaged, so it should not change based on the vial. What can differ with a compounded product is purity, concentration accuracy and stability - none of which this calculator measures.
Is this a dosing recommendation?
No. It only charts the arithmetic of first-order elimination for a half-life and interval - it never suggests a dose or a schedule. For the actual FDA-approved titration schedules by brand, see the semaglutide dosage page.