TL;DR: Liraglutide and semaglutide are both GLP-1 receptor agonists, but they run on completely different clocks. Liraglutide has a half-life near 13 hours, so it escalates daily — 0.6 mg, then +0.6 mg each week to 3.0 mg. Semaglutide sits around 7 days, so it climbs weekly across roughly 16 weeks. That single difference reshapes everything downstream: a 5 mg liraglutide vial is under two days of maintenance dosing, while a 5 mg semaglutide vial is two weeks. Run your own numbers in the liraglutide calculator — this guide explains what it is doing.
Two ladders, two clocks
The reason liraglutida is daily and semaglutide is weekly comes down to pharmacokinetics, not preference. In the original healthy-volunteer study of the molecule (then called NN2211), subcutaneous liraglutide showed a half-life of about 12.6 hours, with an accumulation index of roughly 1.4-1.5 over seven days of daily dosing. Semaglutide, by contrast, carries a half-life close to 168 hours and accumulates about three-fold before reaching steady state at weeks 4-5.
So liraglutide’s concentration is a daily sawtooth — it rises after each injection and falls meaningfully before the next one. Semaglutide’s is a slow plateau that barely notices any individual day. Every practical difference in the dosing math flows from that.
The daily ladder: 0.6 to 3.0 mg in five weeks
Liraglutide’s weight-management escalation is unusually brisk because the compound clears so fast. The standard schedule starts at 0.6 mg once daily for one week, then adds 0.6 mg at weekly intervals:
- Week 1: 0.6 mg daily
- Week 2: 1.2 mg daily
- Week 3: 1.8 mg daily
- Week 4: 2.4 mg daily
- Week 5 onward: 3.0 mg daily
Each rung holds for seven days, and a step can be delayed by an extra week if the gut is complaining. Note the shape: five evenly spaced rungs, each exactly +0.6 mg. That regularity is the one thing that makes liraglutide arithmetic easier than semaglutide’s — every step is the same size, so a single concentration serves the whole ladder.
The glycaemic-control dosing of liraglutide tops out lower, at 1.8 mg daily, which is the rung used in the SUSTAIN 10 head-to-head against semaglutide’s 1.2 mg comparator arm. Weight-management protocols push to 3.0 mg.
The weekly ladder: 0.25 to 2.4 mg over four months
Semaglutide’s escalation looks nothing like that. The rungs are roughly 0.25, 0.5, 1.0, 1.7 and 2.4 mg once weekly, and each one holds for about four weeks rather than one. That is 16 weeks of climbing before you reach the top rung — more than three times as long as liraglutide’s ramp, even though the destination dose is numerically smaller.
The rungs are also not evenly spaced. 0.25 to 0.5 is a doubling; 1.7 to 2.4 is a 41% step. So unlike liraglutide, each semaglutide rung can sensibly get its own reconstitution concentration, because each rung lasts a month and often a whole vial. The full breakdown lives in semaglutide dosing and titration, and the semaglutide calculator handles the per-rung draw volumes.
Liraglutide burns roughly 8-9x the mass per week at maintenance, because it injects seven times instead of once.
How a 5mg or 10mg liraglutide vial actually divides up
Research liraglutide ships lyophilised in 5mg and 10mg vials. Concentration is the usual division:
mg/mL = vial strength (mg) ÷ bacteriostatic water added (mL)
And on a U-100 syringe, 1 mL = 100 units, so mcg per unit = (mg/mL × 1000) ÷ 100.
Worked example — a 10 mg vial reconstituted with 2 mL:
- Concentration: 10 ÷ 2 = 5 mg/mL = 5000 mcg/mL
- Per unit: 5000 ÷ 100 = 50 mcg per unit
At 50 mcg/unit, the entire liraglutide ladder lands on clean, readable marks:
- 0.6 mg = 600 ÷ 50 = 12 units
- 1.2 mg = 24 units
- 1.8 mg = 36 units
- 2.4 mg = 48 units
- 3.0 mg = 60 units
That is the sweet spot. Because liraglutide spans a 5x dose range (0.6 to 3.0 mg) and moves through it in five weeks, one concentration has to serve both ends — and 50 mcg/unit keeps the smallest dose off the crowded bottom of the barrel while keeping the largest under 100 units.
A 5 mg vial with 1 mL gives the same 5 mg/mL and the same unit marks, just half the volume. Reconstitute that 5 mg vial with 2 mL instead and you get 2.5 mg/mL, 25 mcg/unit — now 3.0 mg is 120 units, past a single U-100 barrel. Same peptide, worse ruler.
Doses per vial: the number that surprises people
Here is where the daily-versus-weekly split bites hardest. Doses per vial is just vial strength ÷ dose:
A 10 mg liraglutide vial at maintenance dose lasts three and a bit days. Compare that with semaglutide: a 5 mg semaglutide vial at 2.4 mg weekly is 2 doses, which is two weeks, and at the 0.25 mg starting rung it is 20 doses — nearly five months of injections from one vial.
The full liraglutide escalation phase alone consumes a lot of compound. Weeks 1 through 4 total (0.6 + 1.2 + 1.8 + 2.4) × 7 = 42 mg, which is roughly four 10 mg vials just to reach maintenance. Maintenance then runs 21 mg per week. Semaglutide’s entire 16-week climb totals about 0.25×4 + 0.5×4 + 1.0×4 + 1.7×4 = 13.8 mg — less than one third of liraglutide’s four-week ramp.
There is a practical upside hiding in that. Because a liraglutide vial empties in days rather than weeks, reconstituted-solution storage time is short by construction. A semaglutide vial can sit in the fridge for a month or more between first and last draw; a liraglutide vial at 3.0 mg/day is finished before the week is out.
Missed doses: 13 hours versus 7 days
This is the other place where the two compounds are structurally, not cosmetically, different — and it is downstream of the half-life numbers above.
Liraglutide. With a ~13-hour half-life, skipping one day means roughly 28% of the previous dose remains after 24 hours (24 ÷ 13 ≈ 1.85 half-lives). Skip three days and you are at about 2%. Which is exactly why the labelled guidance says: resume the once-daily schedule at the next scheduled dose, do not double up, and if more than three days have elapsed, restart at 0.6 mg and re-titrate. The gut has lost its tolerance in that window.
Semaglutide. A 7-day half-life means a dose taken two days late still has about 82% of the prior week’s exposure sitting underneath it (48 ÷ 168 ≈ 0.29 half-lives). The guidance follows: if the next scheduled dose is more than 48 hours away, take the missed one; if it is closer than that, skip it and resume the normal day. Nothing collapses.
What the head-to-head data actually showed
Two trials compared them directly, and both favoured semaglutide on the endpoints they measured.
STEP 8 (Rubino et al., JAMA 2022) randomised 338 adults with overweight or obesity and without diabetes to once-weekly semaglutide 2.4 mg or once-daily liraglutide 3.0 mg, open-label, over 68 weeks. Mean weight change was -15.8% with semaglutide versus -6.4% with liraglutide (pooled placebo, -1.9%).
SUSTAIN 10 (Capehorn et al., Diabetes & Metabolism 2020) compared weekly semaglutide 1.0 mg against daily liraglutide 1.2 mg in 577 adults with type 2 diabetes over 30 weeks. HbA1c fell 1.7% versus 1.0%; body weight fell 5.8 kg versus 1.9 kg. Gastrointestinal adverse events and discontinuations were somewhat more frequent on semaglutide (43.9% vs 38.3%, and 11.4% vs 6.6%).
Worth being straight about the comparison: SUSTAIN 10 used a mid-range Liraglutid dose (1.2 mg), not the 1.8 mg glycaemic maximum, so it is not a ceiling-to-ceiling contest. STEP 8 was ceiling-to-ceiling, and it was open-label. Neither trial says anything about lyophilised research material, reconstitution, or the vial arithmetic above — that math is ours, and it is arithmetic rather than evidence.
If you are moving between the two, the equivalence question does not have a clean answer; see switching between GLP-1s and dose equivalence for why milligram-for-milligram conversion does not work here.
Frequently Asked Questions
Is liraglutide daily or weekly?
Liraglutide is once daily. Its half-life is roughly 13 hours, so concentration falls substantially between injections and a daily rhythm is needed to hold a steady level. Semaglutide’s ~7-day half-life is what permits weekly dosing. This is the core structural difference between the two compounds.
How many doses are in a 10mg liraglutide vial?
Divide 10 mg by your daily dose. At the 0.6 mg starting rung that is about 16 days; at 1.8 mg it is 5 days; at the 3.0 mg maintenance dose it is about 3.3 days. The liraglutide calculator computes this alongside your draw volume.
How many units is a 3.0 mg liraglutide dose?
Depends entirely on concentration. A 10 mg vial reconstituted with 2 mL gives 5 mg/mL, or 50 mcg per unit, so 3.0 mg is 60 units on a U-100 syringe. The same 50 mcg/unit puts the 0.6 mg starting dose at 12 units.
Why does liraglutide escalate weekly but semaglutide monthly?
Because escalation intervals track steady state. Liraglutide reaches steady state within a couple of days, so a week is plenty of time to judge tolerance at a rung. Semaglutide needs 4-5 weeks to accumulate to steady state, so four-week holds are the minimum sensible dwell time.
What happens if I miss a liraglutide dose?
Resume at the next scheduled daily dose without doubling. If more than three days have passed, the labelled guidance is to restart at 0.6 mg and re-titrate, because gastrointestinal tolerance fades quickly on a 13-hour half-life. See missed and late doses for the broader logic.
Is semaglutide stronger than liraglutide?
On a milligram basis, yes — 2.4 mg weekly outperformed 3.0 mg daily on weight change in STEP 8 (-15.8% vs -6.4% at 68 weeks) despite being roughly one-ninth the weekly mass. The difference is receptor exposure over time, not potency per injection.
References
- Rubino DM, Greenway FL, Khalid U, et al. “Effect of Weekly Subcutaneous Semaglutide vs Daily Liraglutide on Body Weight in Adults With Overweight or Obesity Without Diabetes: The STEP 8 Randomized Clinical Trial.” JAMA, 2022;327(2):138-150. doi:10.1001/jama.2021.23619.
- Capehorn MS, Catarig AM, Furberg JK, et al. “Efficacy and safety of once-weekly semaglutide 1.0 mg vs once-daily liraglutide 1.2 mg as add-on to 1-3 oral antidiabetic drugs in subjects with type 2 diabetes (SUSTAIN 10).” Diabetes & Metabolism, 2020;46(2):100-109.
- Pi-Sunyer X, Astrup A, Fujioka K, et al. “A Randomized, Controlled Trial of 3.0 mg of Liraglutide in Weight Management.” New England Journal of Medicine, 2015;373:11-22. (SCALE Obesity and Prediabetes)
- Agersø H, Jensen LB, Elbrønd B, Rolan P, Zdravkovic M. “The pharmacokinetics, pharmacodynamics, safety and tolerability of NN2211, a new long-acting GLP-1 derivative, in healthy men.” Diabetologia, 2002;45(2):195-202.
- Hall S, Isaacs D, Clements JN. “Pharmacokinetics and Clinical Implications of Semaglutide: A New Glucagon-Like Peptide (GLP)-1 Receptor Agonist.” Clinical Pharmacokinetics, 2018;57(12):1529-1538. doi:10.1007/s40262-018-0668-z.
- Wilding JPH, Batterham RL, Calanna S, et al. “Once-Weekly Semaglutide in Adults with Overweight or Obesity.” New England Journal of Medicine, 2021;384:989-1002. (STEP 1)
This article is a research and educational reference only; it is not medical advice, and research-grade material is not for human consumption.