Semaglutide Dosage Calculator

How Semaglutide Dosage Calculation Works

This semaglutide dosage calculator converts your weekly dose in mg into the exact insulin syringe units to draw. Semaglutide peptide is supplied as a lyophilized powder and reconstituted with bacteriostatic water (BAC water) before subcutaneous injection. Once reconstituted, the solution has a concentration in mcg/mL. To draw the correct dose on an insulin syringe, you divide your dose by the concentration and multiply by the syringe factor.

1. Concentration (mcg/mL) = Vial size (mg) × 1,000 ÷ BAC water added (mL)
2. Units to draw = (Target dose in mcg ÷ Concentration) × 100 for U-100 syringe

Example: 5 mg vial + 2 mL BAC water = 2,500 mcg/mL. A 0.5 mg weekly dose (500 mcg) = 500 ÷ 2,500 × 100 = 20 units on U-100 (0.20 mL). Enter your values above and the calculator handles the math instantly.

Semaglutide Dose Titration Schedule

GLP-1 agonists like semaglutide require gradual dose escalation to minimize nausea and other GI effects. A typical research protocol follows these steps, holding each dose for 4 weeks:

• 0.25 mg/week — starting dose (10 units on U-100 at 2,500 mcg/mL)
• 0.5 mg/week — step 2 (20 units)
• 1.0 mg/week — step 3 (40 units)
• 1.7 mg/week — step 4 (68 units)
• 2.4 mg/week — maximum dose (96 units)

Always consult a licensed healthcare provider before following any dosing protocol. Slow titration significantly improves tolerability.

Choosing BAC Water Volume for Semaglutide

The BAC water volume you add to the vial determines the concentration and how many units you draw per dose. For a 5 mg vial:

• 1 mL BAC water: 5,000 mcg/mL — each U-100 unit = 50 mcg. A 0.5 mg dose = 10 units.
• 2 mL BAC water: 2,500 mcg/mL — each U-100 unit = 25 mcg. A 0.5 mg dose = 20 units.
• 5 mL BAC water: 1,000 mcg/mL — each U-100 unit = 10 mcg. A 0.5 mg dose = 50 units.

Aim for a draw in the 10–50 unit range. Very small draws (under 5 units) have disproportionately high measurement error. Use the peptide reconstitution calculator to find the ideal BAC water volume for your weekly dose.

U-100 vs. U-40 Syringes

Insulin syringes come in two calibrations: U-100 (100 units per mL; 1 unit = 0.01 mL) and U-40 (40 units per mL; 1 unit = 0.025 mL). Using the wrong syringe type results in a 2.5× dosing error in either direction. U-100 syringes are the US standard and strongly preferred for semaglutide dosing. Always verify the marking on the syringe barrel before drawing.

Semaglutide vs. Other GLP-1 Peptides

Semaglutide is a GLP-1 single agonist. Tirzepatide adds GIP receptor activation (dual agonist), and retatrutide adds glucagon receptor activation on top (triple agonist). From a dosing calculation standpoint, all three use the same formula — just different milligram amounts. See the tirzepatide dosage calculator and retatrutide dosage calculator for peptide-specific defaults.

Semaglutide Benefits and Clinical Evidence

Semaglutide reduces appetite primarily by activating GLP-1 receptors in the hypothalamus and brainstem, suppressing hunger signals and promoting satiety. It also slows gastric emptying, which extends the sensation of fullness after meals and blunts postprandial glucose spikes. At the 2.4 mg/week research dose, these combined effects produce sustained caloric reduction.

The STEP 1 trial (New England Journal of Medicine, 2021) reported approximately 14.9% mean body weight reduction over 68 weeks — roughly 3× the weight loss seen with lifestyle intervention alone. Participants also saw improvements in waist circumference, blood pressure, and lipid profiles. The cardiovascular benefit is well-established in T2D patients: SUSTAIN-6 showed a 26% relative risk reduction in MACE (cardiovascular death, non-fatal MI, non-fatal stroke) vs. placebo.

• Weight loss: ~15% body weight at 68 weeks (2.4 mg/week dose, STEP 1)
• Glycemic control: significant HbA1c reduction in T2D; improved insulin sensitivity in non-diabetics
• Cardiovascular: 26% reduction in MACE (SUSTAIN-6, T2D population)
• Liver fat: reduction in hepatic steatosis in early NAFLD research
• Blood pressure: modest systolic reduction (~3–5 mmHg) as a secondary effect of weight loss

Semaglutide Side Effects and Safety Profile

Gastrointestinal effects are by far the most common adverse events with semaglutide and are the primary reason the dose titration schedule exists. Most GI side effects peak in the first 4–8 weeks and gradually improve as the body adapts to GLP-1 receptor activation.

• Nausea — ~44% incidence in clinical trials; most prominent at dose-up steps
• Diarrhea — ~30%; usually transient and self-limiting
• Vomiting — ~24%; most severe in first 2 weeks after dose escalation
• Constipation — ~24%; from reduced GI motility; stays hydrated and increases fiber
• Abdominal pain — ~20%; generally mild and fasting-related
• Pancreatitis — rare; discontinue and seek care for severe, persistent abdominal pain
• Gallbladder disease — increased risk with rapid weight loss; report right upper quadrant pain

Semaglutide carries a GLP-1 class boxed warning for thyroid C-cell tumors (rodent data; human clinical significance not established). It is contraindicated with a personal or family history of medullary thyroid carcinoma or MEN2. Always consult a licensed healthcare provider before use.

Storage and Safe Handling

Reconstituted semaglutide should be refrigerated at 2–8°C and used within 28 days. Never freeze reconstituted peptide. Wipe the vial stopper with an alcohol swab before each draw, and use a fresh needle for every injection. Dispose of needles and syringes in a puncture-resistant sharps container.