Tirzepatide Dosing Calculator

Dose

2.5-15 mg

Frequency

Once weekly

Duration

Ongoing

Route

Subcutaneous

Uses compounded vials (various concentrations); requires dose calculator tools like Fat Scientist; community reports dosing in units rather than mg

Dose

7.5-10 mg

Frequency

Once weekly

Duration

Ongoing

Route

Subcutaneous

Many community members stabilize at 7.5-10 mg rather than escalating to maximum 15 mg dose; reports adequate weight loss with fewer GI side effects

Dose

5-15 mg (split into 2 injections)

Frequency

2 times weekly (splitting weekly dose)

Duration

Ongoing

Route

Subcutaneous

Some users split their weekly dose into two injections 3-4 days apart to maintain more consistent drug levels and reduce peak-related side effects

Dose

Start 2.5 mg weekly SC for 4 weeks, then escalate to 5 mg weekly. May increase by 2.5 mg increments every 4 weeks to maximum 15 mg weekly.

Frequency

Once weekly subcutaneous injection

Duration

Ongoing; long-term maintenance therapy

2.5 mg is the starting dose for GI tolerability, not a therapeutic dose. Minimum therapeutic dose is 5 mg. Dose escalation: 2.5 mg -> 5 mg -> 7.5 mg -> 10 mg -> 12.5 mg -> 15 mg. Each increase after at least 4 weeks.

Dose

Start 2.5 mg weekly SC for 4 weeks, then escalate to 5 mg weekly. May increase by 2.5 mg increments every 4 weeks. Target maintenance dose is typically 10 mg or 15 mg weekly.

Frequency

Once weekly subcutaneous injection

Duration

Ongoing; long-term weight management

Same escalation schedule as Mounjaro. Higher maintenance doses (10-15 mg) generally needed for maximal weight loss efficacy. If patient does not tolerate a dose increase, consider maintaining current dose or returning to previously tolerated dose.

How much bacteriostatic water should I add to a 15 mg vial of Tirzepatide?

The community standard is 2 mL of bacteriostatic water for a 15 mg Tirzepatide vial. That gives a concentration of 7.50 mg/mL, so a 2.5 mg dose is 33.3 units on a U-100 insulin syringe. Adding 1 mL instead doubles the concentration to 15.00 mg/mL and halves the draw to 16.7 units. Less water = smaller injection volume but harder to measure precisely.

How many syringe units is a 2.5 mg dose of Tirzepatide?

On a standard U-100 insulin syringe, a 2.5 mg dose of Tirzepatide is 33.3 units when the 15 mg vial is reconstituted with 2 mL of bacteriostatic water (7.50 mg/mL). If you use 1 mL of bac water instead, draw 16.7 units (15.00 mg/mL).

What is the standard Tirzepatide dose?

Community-reported protocols for Tirzepatide typically use 2.5 mg–15 mg once weekly via Subcutaneous. 2.5 mg is a common starting dose. Mirrors FDA-approved schedule: 2.5 mg x4 weeks, 5 mg x4 weeks, 7.5 mg x4 weeks, 10 mg x4 weeks, 12.5 mg x4 weeks, then 15 mg maintenance

How long does a vial of Tirzepatide last at 2.5 mg once weekly?

A 15 mg vial of Tirzepatide contains roughly 6 doses at 2.5 mg per injection. At once weekly dosing, that is approximately 42 days (about 6 weeks) of supply per vial. Reconstituted Tirzepatide should generally be used within 28 days when refrigerated.

Where do you inject Tirzepatide?

Tirzepatide is typically injected subcutaneous. Common sites reported in the literature and by users include: Abdomen (at least 2 inches from navel), Front of thigh (middle third), Upper arm (back, upper outer area -- may require assistance). Rotate sites with each injection to reduce localized irritation.

Can I use sterile water instead of bacteriostatic water for Tirzepatide?

Bacteriostatic water (containing 0.9% benzyl alcohol as a preservative) is strongly preferred for multi-dose vials like Tirzepatide because it inhibits microbial growth and lets a single vial be used over multiple weeks. Sterile water has no preservative and should generally be reserved for single-use preparations only.