Tirzepatide Dosage Calculator

How Tirzepatide Dosage Calculation Works

This tirzepatide dosage calculator converts your weekly dose in mg into the exact insulin syringe units to draw. Tirzepatide peptide is supplied as a lyophilized powder and reconstituted with bacteriostatic water (BAC water) before subcutaneous injection. The concentration of the resulting solution determines how many insulin syringe units you draw for each weekly dose.

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: 10 mg vial + 2 mL BAC water = 5,000 mcg/mL. A 5 mg weekly dose (5,000 mcg) = 5,000 ÷ 5,000 × 100 = 100 units on U-100 (1.0 mL). Enter your vial size, BAC water volume, and desired dose above for an instant result.

Tirzepatide Dose Titration Schedule

Tirzepatide titrates more gradually than semaglutide because it starts at a higher base dose. Research protocols typically hold each step for 4 weeks:

• 2.5 mg/week — starting dose (50 units on U-100 at 5,000 mcg/mL)
• 5 mg/week — step 2 (100 units)
• 7.5 mg/week — step 3 (150 units)
• 10 mg/week — step 4 (200 units)
• 12.5 mg/week — step 5 (250 units — split into two injections or increase concentration)
• 15 mg/week — maximum dose (300 units or 150 units × 2 at 5,000 mcg/mL)

Always consult a licensed healthcare provider before following any dosing protocol. Dose escalation should pause if significant GI side effects occur.

Choosing BAC Water Volume for Tirzepatide

Because tirzepatide doses are larger than semaglutide doses, a higher-concentration reconstitution is often more practical:

• 10 mg vial + 1 mL BAC: 10,000 mcg/mL — each U-100 unit = 100 mcg. A 5 mg dose = 50 units.
• 10 mg vial + 2 mL BAC: 5,000 mcg/mL — each U-100 unit = 50 mcg. A 5 mg dose = 100 units.
• 5 mg vial + 1 mL BAC: 5,000 mcg/mL — each U-100 unit = 50 mcg. A 2.5 mg dose = 50 units.

For doses above 10 mg/week, using 1 mL BAC water per 10 mg vial (10,000 mcg/mL) keeps draw volumes under 1.5 mL. Use the peptide reconstitution calculator to find the right concentration for your weekly dose.

Tirzepatide vs. Semaglutide and Retatrutide

Tirzepatide activates both GLP-1 and GIP receptors. Semaglutide activates GLP-1 only, while retatrutide adds glucagon receptor activation to both GLP-1 and GIP (triple agonist). The dual GIP agonism in tirzepatide is believed to improve glucose-dependent insulin secretion and may reduce the nausea associated with GLP-1 alone. For dose calculation purposes, all three use the same formula. See the semaglutide dosage calculator and retatrutide dosage calculator for peptide-specific defaults.

U-100 vs. U-40 Syringes

A U-100 syringe has 100 units per mL (1 unit = 0.01 mL); a U-40 has 40 units per mL (1 unit = 0.025 mL). Drawing the same unit count on a U-40 syringe delivers 2.5× the volume — and 2.5× the dose. U-100 syringes are the US standard. Always confirm the syringe type before drawing.

Tirzepatide Benefits and Clinical Research

Tirzepatide's dual GLP-1/GIP mechanism explains why it outperforms single agonists like semaglutide for weight loss. The GIP receptor is expressed in adipose tissue and the central nervous system, and its activation is thought to reduce GLP-1-induced nausea while adding complementary effects on insulin secretion and fat metabolism. This synergy allows tirzepatide to achieve greater weight reduction with a similar or better tolerability profile than GLP-1 alone.

The SURMOUNT-1 trial (NEJM 2022) enrolled adults with obesity (no T2D) and reported mean body weight reductions of 15.0%, 19.5%, and 20.9% at 5 mg, 10 mg, and 15 mg/week respectively at 72 weeks. At the 15 mg dose, 57% of participants achieved at least 20% weight loss — a level previously achievable only with bariatric surgery. The SURPASS-CVOT trial is ongoing to confirm cardiovascular benefits.

• Weight loss: up to 22.5% body weight at 72 weeks (15 mg/week, SURMOUNT-1)
• HbA1c: mean reduction of ~2.0–2.3 percentage points in T2D patients (SURPASS trials)
• Visceral fat: significant reduction in abdominal adiposity across all dose groups
• GI tolerability: lower nausea incidence (~31%) vs. semaglutide (~44%) at comparable weight-loss outcomes
• Lipid profile: improvements in triglycerides and HDL cholesterol as secondary effects of weight loss

Tirzepatide Side Effects and Safety Profile

Tirzepatide's GI side effects follow the same pattern as other GLP-1 class peptides but are generally considered less severe than semaglutide at doses producing comparable weight loss, which researchers attribute to the GIP component partially moderating GLP-1-driven GI effects.

• Nausea — ~31% in SURMOUNT-1 (vs. ~44% for semaglutide); most prominent at dose-up steps
• Diarrhea — ~23%; transient and most common in the first 4–8 weeks
• Vomiting — ~18%; typically dose-escalation related
• Constipation — ~17%; from reduced GI motility; hydration and fiber help
• Injection site reactions — erythema, swelling; rotate injection sites to minimize
• Decreased appetite — expected effect; monitor protein and micronutrient intake
• Gallbladder disease — increased risk with rapid weight loss; report RUQ pain

Tirzepatide carries the same GLP-1 class boxed warning for thyroid C-cell tumors (rodent data; human significance unclear) and is contraindicated with a personal or family history of medullary thyroid carcinoma or MEN2. Pancreatitis is a rare but serious risk. Always consult a licensed healthcare provider before use.

Storage and Safe Handling

Reconstituted tirzepatide should be refrigerated at 2–8°C and used within 28 days. Do not freeze reconstituted peptide. Wipe the vial stopper with an alcohol swab before each draw, and use a fresh needle for every injection. Dispose of sharps in a puncture-resistant container. Unreconstituted lyophilized powder should be stored frozen at −20°C.