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Semaglutide Half-Life Calculator

Semaglutide’s prescribing information states a half-life of approximately one week. Dosed once weekly, that is roughly one half-life per interval — which is the arithmetic behind why it takes about five weeks to approach a steady level.

Last reviewed: September 21, 2026

A half-life and a schedule give a curve. Each dose decays on its own and the amounts add, which is what makes a compound accumulate or not.

Compound

~168 hours (~7 days)

Only compounds whose half-life Prof. Peptide can cite appear here. Half-life ~1 week. Source: FDA prescribing information (Wegovy / Ozempic).

Dose (any unit — the curve is in that unit)

Hours between doses

Hours to model

Worked example

A half-life of 168 hours (the FDA label’s approximately one week), dosed once weekly (168-hour interval):

Half-lives per interval	168 h ÷ 168 h = 1.000
Accumulation ratio	×2.000
Steady-state peak / trough	2.000 / 1.000, per dose unit
Near steady state after	840 hours (35 days, five half-lives)

Enter a dose, 168 for the interval, and any span into the calculator above and it returns the same ratios and a chart of the shape.

This is a single-compartment model. It assumes each dose is fully present the moment it’s given and decays at a constant rate. It ignores absorption (a real curve rises to a peak over hours rather than jumping), distribution into tissue, and every difference between one person and another. It is the arithmetic of a half-life and a schedule, not a prediction about a body.

FAQ

semaglutide half life calculator accumulation

This page models semaglutide's accumulation from its FDA-labelled half-life of approximately one week and a dosing schedule you enter. Dosed once weekly — semaglutide's approved interval — that's almost exactly one half-life per dose, which is why the steady-state peak settles at about twice a single dose.

How long does semaglutide take to reach steady state?

About five half-lives, or roughly 35 days (5 weeks) at the FDA label's approximately one-week half-life. That's when the model considers accumulation about 97% complete, at a fixed weekly dose.

Does semaglutide accumulate in the body?

Modelled at a one-week half-life and once-weekly dosing, yes — the steady-state peak comes to about twice the peak after a single dose, because roughly half of each dose is still present when the next one lands.

To compare semaglutide’s accumulation against tirzepatide, retatrutide and cagrilintide, see the GLP-1 half-life calculator. For dosing and reconstitution arithmetic, see the semaglutide reconstitution calculator.