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Semaglutide half-life calculator and dose-level plotter

Updated by the GLP Ladder Editorial Team. Editorial policy.

Short answer

Semaglutide's half-life is about 7 days, so ke = ln2 ÷ 7 = 0.099 per day and 50% of the amount present remains a week later. Weekly doses build by R = 1 ÷ (1 − e^(−7ke)) = 2× and reach about 97% of steady state after 5 half-lives (35 days). Modeled estimate, as of Oct 19, 2026.

Published ladders

Trial or label schedules as published, for modeling only.

Dosing tiers (up to 12)

Tier 1

Tier 2

Tier 3

Tier 4

Tier 5

Mark missed doses

Unchecked doses are modeled as not taken.

Peak amount
4.28 mg-eq
Stable window from
Day 126
Stable average
3.38 mg-eq
Accumulation R
2×
Semaglutide: modeled relative amount for the Wegovy label ladder to 2.4 mgStep chart of weekly doses (0.25 mg, 0.5 mg, 1 mg, 1.7 mg, 2.4 mg) above a curve of the modeled amount in the body, peaking at 4.28 mg-equivalents in week 28. Weekly values are in the table below.stable window01.252.53.755mg-eq048121620242832weeks from start0.25 mg0.5 mg1 mg1.7 mg2.4 mg
  • Dose ladder: mg per dose for each tier
  • One tick per dose; an open circle is a missed dose
  • Modeled relative amount in mg-equivalents (F = 1), not plasma concentration
  • Stable window: weekly troughs change by under 5%

How the model works.

Day 191: 4.278 mg-eq modeled. Move the slider or hover the chart for the per-dose breakdown.

Weekly data table
Modeled amount by week, Wegovy label ladder to 2.4 mg, start Oct 19, 2026 (mg-equivalents)
WeekStartsDose mgPeakTroughAverage
1Oct 19, 20260.250.21500.165
2Oct 26, 20260.250.330.1310.263
3Nov 2, 20260.250.3870.1970.312
4Nov 9, 20260.250.4160.2290.336
5Nov 16, 20260.50.6450.2460.513
6Nov 23, 20260.50.7680.3850.617
7Nov 30, 20260.50.8290.4550.669
8Dec 7, 20260.50.860.4890.695
9Dec 14, 202611.3030.5071.038
10Dec 21, 202611.5420.7771.24
11Dec 28, 202611.6620.9131.342
12Jan 4, 202711.7220.9811.392
13Jan 11, 20271.72.351.0141.879
14Jan 18, 20271.72.6891.3982.166
15Jan 25, 20271.72.8591.592.309
16Feb 1, 20271.72.9451.6862.381
17Feb 8, 20272.43.5841.7342.878
18Feb 15, 20272.43.932.1253.17
19Feb 22, 20272.44.1042.323.316
20Mar 1, 20272.44.1912.4183.389
21Mar 8, 20272.44.2352.4673.426
22Mar 15, 20272.44.2562.4913.444
23Mar 22, 20272.44.2672.5043.453
24Mar 29, 20272.44.2732.513.458
25Apr 5, 20272.44.2752.5133.46
26Apr 12, 20272.44.2772.5143.461
27Apr 19, 20272.44.2772.5153.462
28Apr 26, 20272.44.2782.5153.462
29May 3, 2027—2.61.3051.879
30May 10, 2027—1.30.6530.94
31May 17, 2027—0.650.3260.47
32May 24, 2027—0.3250.1630.235

Math, parameters and sources: model card.

How the plotter models levels

Each dose is treated as a one-compartment, first-order absorption curve (the Bateman function), and the curves for every dose are added together. The rate of elimination comes from the half-life (ke = ln2 ÷ t½) and the rate of absorption is solved from the published time to peak. The result is a relative amount in mg-equivalents with bioavailability set to 1, which is why it is useful for comparing schedules and not for reading a blood level.

Model parameters and derived constants (one weekly dose interval, τ = 7 days)
Compoundt½ (days)tmax (h)ke (/day)ka (/day)RLeft after 7 d
Retatrutide6240.1155253.53711.80330.4454
Tirzepatide5240.1386293.31221.61010.3789
Semaglutide7360.0990212.151420.5

Published ladders preloaded

The preset buttons load schedules exactly as published. They are there so you can see what a trial or label schedule looks like on the curve; none of them is a recommendation.

Ladders available in this plotter, with their source
LadderSteps (mg, weekly)Weeks per stepSource
Semaglutide Wegovy label ladder to 2.4 mg0.25 → 0.5 → 1 → 1.7 → 2.44Novo Nordisk, Jun 18, 2026
Semaglutide Ozempic label ladder to 2 mg0.25 → 0.5 → 1 → 24Novo Nordisk, Jun 1, 2026

Reading the stable window

With a fixed weekly dose, each week's lowest point (the trough) rises less than the week before. The plotter shades the "stable window" from the first week in which two consecutive week-over-week trough changes are both under 5%. After any dose increase the climb restarts, so a titration ladder usually reaches its stable window only on the final step. A missed dose shows up as a dip in both the curve and the weekly table.

How to read a dose-level curve (Semaglutide, 1 mg weekly for 10 weeks, modeled)
Annotated modeled curve for weekly semaglutide: first peak, trough, accumulation, stable window and washout, keyed to the list below. 1 2 3 4 5
  1. First peak about 36 hours after the first dose (time to peak).
  2. Trough: the lowest point, just before the next weekly dose.
  3. Accumulation: each dose adds to what is left, so peaks and troughs climb toward about 2× a single dose.
  4. Stable window: from about day 28, the weekly trough changes by less than 5% from one week to the next.
  5. Washout: after the last dose the amount halves every 7 days.

Relative amount (mg-equivalents), not a blood level. Model and sources: model card.

Frequently asked questions

What is the half-life of semaglutide?

FDA label: elimination half-life of about 1 week. The plotter uses 7 days and a time to peak of 36 hours.

How long does semaglutide take to reach steady state?

About 5 half-lives, or roughly 35 days at a constant weekly dose, reaches about 97% of steady state (1 − 2^−5 = 96.9%). Each dose increase restarts that climb toward a new plateau. The plotter marks a "stable window" when the weekly trough changes by less than 5% across two consecutive weeks.

How much semaglutide is left after a week?

By elimination alone, e^(−7 × 0.099) = 0.5, so about 50% of the amount present at the start of the week remains at its end. That carry-over is why weekly doses accumulate by about 2× before levels flatten.

Is the plotter output a blood level?

No. It is a relative amount in mg-equivalents from a one-compartment model with first-order absorption and bioavailability set to 1. Real plasma concentrations depend on body size, absorption site and individual clearance. Use the curve to compare schedules, not to judge your own levels.

Is semaglutide FDA approved?

Yes. FDA approved as Ozempic (type 2 diabetes) and Wegovy (weight management, cardiovascular risk reduction). Numbers on this page quote the FDA prescribing information; your prescriber sets your dose.

Sources

  1. WEGOVY (semaglutide) injection, for subcutaneous use; WEGOVY (semaglutide) tablets, for oral use - Full Prescribing Information (SPL, Revised 6/2026). Novo Nordisk / National Library of Medicine DailyMed, Jun 18, 2026. Accessed Oct 19, 2026.
  2. OZEMPIC (semaglutide) injection, for subcutaneous use - Full Prescribing Information (SPL). Novo Nordisk / National Library of Medicine DailyMed, Jun 1, 2026. Accessed Oct 19, 2026.

The curve and figures are a modeled relative amount in the body (mg-equivalents), not a blood level.

Printed from GLP Ladder. To recreate this result, open https://glpladder.com/tools/semaglutide-plotter/

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