How pen clicks work: 300 clicks, mcg per click, and how to check any protocol's arithmetic

The one rule: a pen is 300 clicks

Every pre-mixed pen we write protocols around holds 300 clicks of the dial, however much compound is inside it. The dial does not know what the pen contains; it only knows how far it has turned. That means the amount of compound in a single click depends entirely on how many milligrams went into the pen. A pen with more compound in the same volume gives more per click; a pen with less gives less. The volume per click is constant. The dose per click is not.

So the whole of pen arithmetic reduces to one line:

mcg per click = (mg in the pen × 1,000) ÷ 300

Multiplying by 1,000 turns milligrams into micrograms; dividing by 300 spreads the pen across its clicks. If you prefer, the same thing in milligrams is mg per click = mg in the pen ÷ 300, which is handy for the high-concentration pens where doses are written in milligrams anyway.

Two worked examples

A 10 mg pen

10 mg × 1,000 = 10,000 mcg in the pen. 10,000 ÷ 300 = 33.3 mcg per click. A BPC-157 dose of 250 mcg is therefore 250 ÷ 33.3 = 7.5 clicks, which a protocol rounds to 8 clicks (267 mcg) because half-clicks do not exist. A 500 mcg dose is 15 clicks exactly. This is why most house protocols on 10 mg pens use click counts that are multiples of 3 or 15 — the arithmetic falls out cleanly.

A 24 mg retatrutide pen

24 mg × 1,000 = 24,000 mcg. 24,000 ÷ 300 = 80 mcg per click. The house starting dose for women on retatrutide is 1.5 mg a week, which is 1,500 ÷ 80 = 18.75, written as 19 clicks. The men's start of 2 mg is 2,000 ÷ 80 = 25 clicks exactly. On the 12 mg pen (40 mcg per click) the same milligram doses are simply double the clicks: 38 and 50. Same dose, different pen, different number on the dial — which is the most common place people trip.

Common pens and their clicks

The table covers the pens that appear most often in the protocols we write. The last column is the number you actually use: the micrograms in one click.

Notice the combo pens. A click of a GLOW pen is a click of three compounds at once, each at its own concentration; you cannot dose one of them without the others. That is the trade-off the budget option accepts on purpose, and the reason the full clinical protocol lists every compound in a combo click separately.

From a dose to a pen count

Once you know the clicks per dose, counting pens for a cycle is multiplication:

1. Clicks per dose = dose in mcg ÷ mcg per click (round to a whole click).
2. Doses per week × clicks per dose = clicks per week.
3. Clicks per week × weeks = clicks per cycle. If the dose ramps, add the weeks up separately.
4. Clicks per cycle ÷ 300, rounded up, = pens per cycle.

Example: 500 mcg of BPC-157 from a 10 mg pen, once a day, for 8 weeks. 15 clicks × 7 days × 8 weeks = 840 clicks. 840 ÷ 300 = 2.8, so three pens, with 60 clicks left over at the end. The ramped retatrutide schedule works the same way, just week by week: the house 12-week women's schedule on the 24 mg pen adds up to about 36.5 mg, which is 456 clicks and therefore two pens with roughly a third of the second one unused.

Your full clinical protocol shows this working on its fridge page: clicks per dose, clicks per week, clicks per cycle, pens. If a number there does not reproduce when you redo it, tell your coach — that is exactly what the check is for.

The mistakes we see most

• Assuming a click is a fixed dose. A click is a fixed volume. 10 clicks of a 5 mg pen is half the compound of 10 clicks of a 10 mg pen. Always ask "which pen?" before "how many clicks?".
• Doubling a combo without meaning to. Adding a stand-alone GHK-Cu pen on top of a GLOW pen puts GHK-Cu in twice. The protocol accounts for what is already in the combo; do not add to it.
• Mixing up the 12 mg and 24 mg retatrutide pens. 38 clicks is 3 mg on one and 1.5 mg on the other. The pen in your hand decides the number, not memory.
• Rounding in the wrong direction. A protocol rounds 7.5 clicks to 8, not to 10. Whole clicks only, nearest whole click, never "a bit extra".
• Counting past 100 without a system. High-click doses on low-concentration pens are easy to lose count of. Count in tens and say them out loud.
• Forgetting the leftover. A pen that runs out mid-dose is finished from the next one; note the clicks taken. A leftover third of a pen at the end of a cycle is not a reason to extend it.

None of this is about how a dose is taken — that belongs with your coach and your physician. It is about being able to read the page in front of you and know, independently, that the numbers on it are right. Read next: how to read your protocol and what a 12-week cycle looks like.