Tirzepatide Reconstitution — Volume and Concentration Table

Published 2026-10-09 · Lyophile Editorial

Reconstitution math for tirzepatide reduces to one relationship: concentration equals mass divided by diluent volume. Everything else — units on a U-100 syringe, micrograms per tick mark, draw volume per dose — is derived from that single division. This page gives you the table first, then the arithmetic behind each cell.

For research use only — not clinical guidance.

Tirzepatide reconstitution volume and concentration table

Vial sizes below are the common research formats: 5 mg, 10 mg, 15 mg, 20 mg, 30 mg, and 60 mg. Diluent volumes are 1 mL, 2 mL, and 3 mL. All concentrations are reported in mcg/mL, and the U-100 column is the mass delivered per single unit (0.01 mL) on a U-100 insulin syringe.

| Vial | Diluent | Concentration | Per unit (U-100) | Per 10 units | |---|---|---|---|---| | 5 mg | 1 mL | 5,000 mcg/mL | 50 mcg | 500 mcg | | 5 mg | 2 mL | 2,500 mcg/mL | 25 mcg | 250 mcg | | 5 mg | 3 mL | 1,667 mcg/mL | 16.7 mcg | 167 mcg | | 10 mg | 1 mL | 10,000 mcg/mL | 100 mcg | 1,000 mcg | | 10 mg | 2 mL | 5,000 mcg/mL | 50 mcg | 500 mcg | | 10 mg | 3 mL | 3,333 mcg/mL | 33.3 mcg | 333 mcg | | 15 mg | 1 mL | 15,000 mcg/mL | 150 mcg | 1,500 mcg | | 15 mg | 2 mL | 7,500 mcg/mL | 75 mcg | 750 mcg | | 15 mg | 3 mL | 5,000 mcg/mL | 50 mcg | 500 mcg | | 20 mg | 2 mL | 10,000 mcg/mL | 100 mcg | 1,000 mcg | | 20 mg | 3 mL | 6,667 mcg/mL | 66.7 mcg | 667 mcg | | 30 mg | 3 mL | 10,000 mcg/mL | 100 mcg | 1,000 mcg | | 60 mg | 3 mL | 20,000 mcg/mL | 200 mcg | 2,000 mcg |

Read the table as a grid, not a list. Doubling the diluent halves the concentration. Doubling the vial mass at fixed diluent doubles it. Those two moves generate every cell above.

How do you calculate peptide concentration after reconstitution?

Concentration in mcg/mL equals total peptide mass in micrograms divided by total diluent volume in milliliters. A 5 mg vial contains 5,000 mcg; adding 2 mL of diluent yields 5,000 ÷ 2 = 2,500 mcg/mL. On a U-100 syringe, one unit is 0.01 mL, so each unit carries 25 mcg.

The step-by-step version:

1. Convert mass to micrograms. 1 mg = 1,000 mcg. A 10 mg vial is 10,000 mcg.
2. Note the diluent volume actually added, not the nominal vial size. A "10 mL" vial filled to 2 mL holds 2 mL.
3. Divide: mcg ÷ mL = mcg/mL.
4. Convert to units: mcg/mL × 0.01 = mcg per unit on U-100.

Worked example. 15 mg vial, 3 mL diluent. 15,000 mcg ÷ 3 mL = 5,000 mcg/mL. 5,000 × 0.01 = 50 mcg per unit. A 250 mcg draw is 5 units. A 500 mcg draw is 10 units.

The failure mode here is the nominal-volume trap. Lyophilized peptide cakes occupy volume, and a vial rated "10 mL" may accept only 8–9 mL before the stopper seats. If you assume 10 mL when you delivered 8.5 mL, every downstream concentration is off by roughly 15%. Weigh the diluent, or use a graduated syringe and read the meniscus at eye level.

How much bacteriostatic water for a 5 mg vial?

A 5 mg tirzepatide vial reconstituted with 2 mL of bacteriostatic water gives 2,500 mcg/mL, which is 25 mcg per unit on a U-100 syringe. The 2 mL choice keeps the arithmetic clean and every dose lands on a whole or half unit. Use 1 mL for 5,000 mcg/mL if you need smaller draw volumes.

Bacteriostatic water for reconstitution is preserved with 0.9% benzyl alcohol per USP monograph, which is what allows multi-draw use from a single vial. Sterile water for injection contains no preservative and is single-use only — a real limitation if you plan more than one draw. USP <797> governs compounding hygiene expectations; the preservative does not substitute for aseptic technique.

How many units is 2.5 mg of tirzepatide on a U-100 syringe?

2.5 mg equals 2,500 mcg. On a U-100 syringe the unit count depends entirely on concentration: 2,500 mcg is 50 units at 5,000 mcg/mL, 100 units at 2,500 mcg/mL, and 150 units at 1,667 mcg/mL. The mass is fixed; the syringe reading is not.

That last figure matters. A U-100 insulin syringe typically maxes at 100 units (1 mL) or 50 units (0.5 mL) for the short version. A 150-unit draw does not fit a standard 1 mL barrel. If your target mass requires more than 100 units, either increase the concentration by reducing diluent or split across two syringes — and splitting introduces its own volumetric error.

| Target mass | At 5,000 mcg/mL | At 2,500 mcg/mL | At 1,667 mcg/mL | |---|---|---|---| | 250 mcg | 5 units | 10 units | 15 units | | 500 mcg | 10 units | 20 units | 30 units | | 1,000 mcg | 20 units | 40 units | 60 units | | 2,500 mcg | 50 units | 100 units | 150 units |

U-100 syringe markings and where the error creeps in

U-100 means 100 units per mL, so one unit is exactly 0.01 mL. That is the definition, not an approximation. The precision limit is the barrel, not the math.

• Half-unit markings exist on some 0.3 mL and 0.5 mL barrels; standard 1 mL barrels are whole-unit only.
• Dead space in the hub holds roughly 1–2 units depending on needle gauge and hub design — this volume is drawn but not delivered.
• Reading between two printed lines is a judgment call; ±0.5 unit is realistic, which at 100 mcg/unit is ±50 mcg.
• Silicone lubrication and barrel diameter affect plunger travel; a 1 mL barrel is more accurate at low volumes than a 3 mL barrel drawing the same amount.

The practical rule: draw at least 10 units whenever the target allows, because the relative error at 2–3 units is large. If your protocol needs 250 mcg and your concentration is 100 mcg/unit, you are drawing 2.5 units — near the floor of what a U-100 barrel resolves reliably. Dilute further to move the draw up the barrel.

Common reconstitution errors and how to catch them

Swirling beats shaking. Lyophilized peptides are fragile; vortexing or vigorous shaking can denature the powder and produce a cloudy solution that never fully clears. Roll the vial between your palms or swirl gently, then let it stand.

Cold diluent dissolves slowly. Room-temperature bacteriostatic water wets the cake faster than refrigerated water, and the difference is often several minutes of standing versus an hour.

Pressure differential is the most common cause of a foaming, hard-to-draw vial. If the vial was lyophilized under vacuum, adding diluent without venting pulls liquid in violently. Equalize pressure by inserting a vent needle, or add the diluent slowly down the vial wall.

Record the actual diluent volume on the label, not the intended volume. The single most useful habit in this workflow is writing "2.0 mL added, 2,500 mcg/mL, 25 mcg/unit" directly on the vial with a lab marker. Six weeks later, the intended volume is a memory; the written volume is a fact.

Where to source bacteriostatic water

• BAC Water Depot — bacteriostatic water in sealed multi-draw vials
• Med Lab Supply — sterile diluents and lab consumables
• Mountain Peak Supplies — preservative-containing water for reconstitution

Where to source research peptides

• Alpha Amino USA — per-lot HPLC/MS COA, US-shipped
• Core Peptides — published COAs on request
• Limitless Biotech — third-party tested lots

For research use only — not clinical guidance.