Compounded Tirzepatide Pen Click Calculator: Clicks to mg

1. Choose the pen in your hand. A Zepbound single-dose pen or KwikPen is not set by counting clicks; the calculator shows how each one is set, dates its doses and explains the liquid left in a KwikPen. The click arithmetic is for a compounded click-dosing pen.
2. Type the concentration the way your pen or pharmacy label prints it, such as 20 mg/mL, or as a total such as 40 mg in 2 mL. The calculator repeats back how it read the label, and a total also gives the number of doses in the pen.
3. Enter your prescribed dose in mg, and say whether the numbers in the dose window go up by 1 or by 2 for each click, or enter the mg per click from your pharmacy’s sheet.
4. Read the clicks to dial, what one click holds, the U-100 units and the volume in mL. When the exact count is not a whole number, the calculator also shows the exact figure and the mg that the whole-click count delivers.

To turn clicks into mg, multiply the clicks by the units per click, divide by 100 and multiply by the concentration. On a 20 mg/mL pen at 1 unit per click, 25 clicks is 25 ÷ 100 × 20 = 5 mg. The 100 comes from the U-100 scale, where 1 mL is 100 units and 5 units are 0.05 mL (FDA alert on compounded semaglutide dosing errors).

The calculator runs the same sum from a dose to clicks: clicks = dose in mg ÷ concentration in mg/mL × 100 ÷ units per click. For 5 mg from a 20 mg/mL pen, 5 ÷ 20 = 0.25 mL, and 0.25 × 100 = 25 units, or 25 clicks at 1 unit per click. At 2 units per click it is 12.5 clicks, which no pen can stop at, so the calculator rounds to 13 clicks and shows that they deliver 5.2 mg (13 × 0.4 mg).

One click holds the concentration × units per click ÷ 100. The table uses six example strengths.

One miscounted click is 0.1 mg at 10 mg/mL and 1 unit per click, and 0.8 mg at 40 mg/mL and 2 units per click, eight times as much.

A click count copied from another person’s pen only works at their concentration and click size. The table prices "25 clicks" on four pens; the Zepbound label caps the weekly dose at 15 mg (Zepbound prescribing information, section 2.2).

At 40 mg/mL and 2 units per click, 25 clicks deliver 20 mg, which is 5 mg over the highest labeled weekly dose.

A pen only stops at whole clicks, so the calculator rounds to the nearest one and shows what that count delivers. At 34 mg/mL and 1 unit per click, one click is 0.34 mg:

Rounding is never off by more than half a click, and that half click is a larger share of a small dose. At 10 mg/mL and 1 unit per click, the same four doses come to whole numbers of clicks (25, 50, 100 and 150).

The Zepbound single-dose pen has no dose to set; it clicks once when the injection starts and again when it is complete (Zepbound prescribing information and Instructions for Use). The KwikPen holds four 0.6 mL doses, and you turn its dose knob all the way until it stops at the dose icon (Zepbound KwikPen Instructions for Use, step 11). Both branded pens are explained in what the clicks on a branded pen mean, and the Mounjaro click chart shows the arithmetic online KwikPen charts use, labeled as an assumption.

Compounded drugs are not FDA approved, and FDA does not review them for safety, effectiveness or quality before they are marketed (FDA, concerns with unapproved GLP‑1 drugs). No label fixes the concentration or the click size of a compounded pen, so either can differ on a refill. If a refill comes at 40 mg/mL instead of 20 mg/mL, the 25 clicks that gave 5 mg now give 10 mg.

Recalculate whenever the label changes. If the result does not match the click count on the pharmacy’s instructions, ask the pharmacy before you dial. For the same dose drawn from a vial in syringe units, use the tirzepatide dose calculator.

The Zepbound Medication Guide says that if you take too much, call your healthcare provider or Poison Help line at 1-800-222-1222, or go to the nearest hospital emergency room right away (Zepbound Medication Guide). Tirzepatide’s elimination half-life is about 5 to 6 days, so an extra amount stays in the body for days (Zepbound prescribing information, section 12.3).