Peptide Calculator for Pens, Syringes and Reconstitution

Reconstituting means adding liquid, usually bacteriostatic water, to the powder in the vial. Wipe both stoppers, draw the water into a sterile syringe, and let it run slowly down the inside wall of the vial rather than straight onto the powder. Swirl gently until it clears; do not shake it. Then enter the milligrams in the vial and the millilitres you added, and the calculator gives the dose in syringe units or pen clicks.

There is no single right amount. The water only sets the strength, so pick a volume that makes your dose easy to measure. With 1 mL, the mix is 5 mg per mL and a 250 mcg dose is 5 units on a U-100 syringe. With 2 mL, it is 2.5 mg per mL and the same dose is 10 units. More water means bigger, easier marks to read.

Divide your dose by the amount of peptide in one click. The strength of your mix is the milligrams in the vial divided by the millilitres of liquid, and a one unit click is 0.01 mL. Take 300 mg in 3 mL. That is 100 mg per mL, so one click carries 1 mg and a 25 mg dose is 25 clicks. The calculator above does the sum for any vial.

On a pen where one click is 0.01 mL, a 3 mL cartridge holds 300 clicks. That is the total across every injection, not the most you can dial at once. Most pens stop at 60 clicks per injection, which is 0.6 mL.

It is the largest dose the dial will set in one go. Sixty clicks at 0.01 mL each comes to 0.6 mL. If your dose needs more clicks than that, you can split it across two injections, or mix the peptide more strongly so that each click carries more.

On most 3 mL pens, yes. One click moves 0.01 mL, which is one unit on a U-100 scale, and that is why the two words get swapped so often. Some pens use bigger or smaller steps. If yours does, set the size of one click in the pen settings and the calculator will count in your pen’s own clicks.

Many injection pens have a priming step, where you press out a small amount to clear air from the needle and see that liquid is flowing. Your pen’s instructions are the right guide here. If you prime, choose how many clicks in the pen settings. The calculator takes them off the cartridge total, so the number of injections it shows stays realistic.

A click is a fixed size, so a pen can only deliver whole multiples of it. The calculator rounds to the nearest click and tells you how far off that leaves you. When the gap matters, it also suggests a slightly different amount of liquid that lands exactly on a click.

It depends on the strength of the mix. With 5 mg in 2 mL, which is 2,500 mcg per mL, 100 mcg is 4 units. With 5 mg in 1 mL it is 2 units. Use syringe mode with your own numbers for the exact figure.

Only part of it. The cartridge takes 3 mL, so it holds about 60% of the peptide and the rest stays in the vial. The strength of the liquid does not change, so the clicks for each dose stay the same. The calculator points this out when it happens.

Turn the dose into mcg first, since 1 mg is 1,000 mcg. Then divide by the strength of your mix in mcg per mL, which gives the volume in mL, and multiply by 100 to get units on a U-100 insulin syringe. With 5 mg in 2 mL, the strength is 2,500 mcg per mL. A 0.5 mg dose is 500 mcg, which is 0.2 mL, or 20 units. Enter the vial, the water and the dose in the calculator and it does these steps for you.

One mg is 1,000 mcg. Use the mg and mcg switch beside the dose box and the calculator converts for you, so 2.5 mg becomes 2,500 mcg. Your answer stays the same either way.

Reconstituted peptide is usually kept in the fridge for around 28 to 30 days. Tell the calculator how often you inject and it works out whether your cartridge or vial will run out before then.