HGH Pen Sizes: 30iu vs 100iu

📅 June 26, 2026 ⏱️ 4 min read ✍️ Team TPS

A 100iu pen is not “a bigger 30iu pen”, the concentration is different, so the same dial number does not deliver the same amount. That is the part that costs people money, and occasionally more than money.

What the iu figure describes

The iu number on an HGH pen is the total activity in the cartridge, not the strength of a dose. A 30iu pen holds 30 international units in total; a 100iu pen holds 100. Both are dialled in units of volume.

So the relationship between “one click” and “how much growth hormone” depends entirely on how much total activity was dissolved into the cartridge volume. More total iu in a similar volume means a more concentrated solution, which means each click carries more.

This is the same trap that applies across the whole pen category, and it is worth reading how to read a peptide pen dial once properly rather than assuming.

The practical consequence

If you move from a 30iu pen to a 100iu pen and keep dialling the number you are used to, you are not continuing your previous routine. You have changed the amount delivered, without changing anything you can see on the dial.

The correction is arithmetic, not intuition: work out the per-unit value for the new pen from its own total and volume, then set the dial to match the amount you were actually taking before.

Which size makes sense

The 30iu pen suits anyone starting, anyone assessing tolerance, and anyone who would rather not commit to a large quantity of a compound they have not used before. It also limits how long a single cartridge sits in use.

The 100iu pen is the better cost-per-iu proposition and means fewer cartridge changes. It suits an established routine where the amount used is known and stable.

There is a third consideration people forget: an opened cartridge is on a clock. A large pen used at a small daily amount can outlive its own in-use window, at which point the saving is theoretical. Buying the larger pen only saves money if you actually get through it while it is still good.

Somatropin versus everything else

Both of these are growth hormone itself. That is a different proposition from a secretagogue, which asks your own pituitary to release more of yours. The two are not interchangeable and the comparison is not close, HGH kits, pens and secretagogues compared covers where each fits.

If the goal is GH pathway support rather than exogenous GH, the Ipamorelin + CJC-1295 pen is the relevant product, not a larger somatropin pen.

Why the pen format matters more here than elsewhere

Traditional HGH supply is a lyophilised kit: powder in a vial, bacteriostatic water, reconstitute, draw with an insulin syringe. Every one of those steps is somewhere the amount can go wrong, and growth hormone is a fragile molecule that does not enjoy being shaken or handled repeatedly.

A pre-filled pen removes the reconstitution step, keeps the cartridge sealed between uses, and replaces the syringe with a mechanical dial. For a compound this sensitive to handling, that is the strongest case the format has. Peptide pens vs vials covers the general trade-off.