Calculator
Pen & Cartridge Calculator
Convert any pre-mixed reusable peptide pen into the exact dial-click count for any research dose. Built for Retatrutide, Tirzepatide, NAD+, GHK-Cu, L-Glutathione, GLOW, KLOW and every other cartridge variant stocked by reference suppliers.
Inputs
Pick a preset to auto-fill mass, cartridge and common dose.
Standard reusable pens are 300 clicks.
Leave at 0 to skip the cost-per-dose calculation.
Results
Concentration
13.33 mg/mL
Dial position
7.5 clicks
Volume per dose
0.075 mL
Doses remaining
~40
One full pen at this dose
40 × 1.000 mg
Dial pen to 7.5 clicks for injection, or draw 7.5 units on a U-100 refill syringe (0.075 mL).
Calculations run entirely in your browser; no inputs leave your device. For laboratory / research-stage reference only.
Reference table — every common pen preset
Click any row to load that preset into the calculator above. Sort by any column.
| Pen ↑ | Mass | Cartridge | mg/mL | Common dose | Clicks | |
|---|---|---|---|---|---|---|
| GHK-Cu 100 mg pen | 100 mg | 3 mL · 300 clicks | 33.33 | 3 mg | 9.0 | |
| GHK-Cu 200 mg pen | 200 mg | 3 mL · 300 clicks | 66.67 | 3 mg | 4.5 | |
| GLOW (50/10/10) 70 mg penTotal blend mass; dose is per-blend not per-component | 70 mg | 3 mL · 300 clicks | 23.33 | 3.5 mg | 15.0 | |
| KLOW (10/10/50/10) 80 mg penTotal blend mass; dose is per-blend not per-component | 80 mg | 3 mL · 300 clicks | 26.67 | 4 mg | 15.0 | |
| L-Glutathione 1800 mg pen | 1800 mg | 3 mL · 300 clicks | 600.00 | 200 mg | 33.3 | |
| NAD+ 1000 mg pen | 1000 mg | 3 mL · 300 clicks | 333.33 | 100 mg | 30.0 | |
| NAD+ 1800 mg pen | 1800 mg | 3 mL · 300 clicks | 600.00 | 200 mg | 33.3 | |
| Retatrutide 24 mg penTitration / starting dose tier | 24 mg | 3 mL · 300 clicks | 8.00 | 0.5 mg | 6.3 | |
| Retatrutide 40 mg pen | 40 mg | 3 mL · 300 clicks | 13.33 | 1 mg | 7.5 | |
| Retatrutide 60 mg pen | 60 mg | 3 mL · 300 clicks | 20.00 | 2 mg | 10.0 | |
| Semaglutide 15 mg penWeekly titration; starting tier | 15 mg | 3 mL · 300 clicks | 5.00 | 0.25 mg | 5.0 | |
| Tesamorelin 20 mg pen | 20 mg | 3 mL · 300 clicks | 6.67 | 1 mg | 15.0 | |
| Tirzepatide 40 mg pen | 40 mg | 3 mL · 300 clicks | 13.33 | 2.5 mg | 18.8 | |
| Tirzepatide 68 mg pen | 68 mg | 3 mL · 300 clicks | 22.67 | 5 mg | 22.1 |
How the maths works
A reusable injection pen has two key numbers stamped on the cartridge: the total peptide mass (for example 40 mg of Retatrutide) and the cartridge volume (almost always 3 mL on modern reusable pens). The dial mechanism breaks that 3 mL into a fixed number of graduated clicks — 300 is the standard on the cartridges supplied by research-grade vendors. Each click advances the piston by 0.01 mL.
That means the concentration is fixed at penMg ÷ cartridgeMl mg/mL, and the click count required to deliver a target dose is (doseMg ÷ penMg) × totalClicks. The calculator above evaluates both formulas live as you type, and the visual dial mirrors the result so the dial position is unambiguous when you transfer the math to the physical pen.
Reverse mode
Sometimes a researcher knows the dial position they want to fix on (for example, an even 10 clicks for simple counting) and needs to know what dose that delivers. Toggle Clicks → dose on the calculator to flip the math direction.
Pre-mixed combo pens
Some healing blends — notably KLOW (10/10/50/10) and GLOW (50/10/10) — are increasingly supplied as pre-mixed cartridges. For these the per-click dose refers to the blend total; the individual component masses scale proportionally. For per-component breakdowns of a single multi-peptide draw, use the Dosage Calculator in combo mode.
Related tools
- Dosage Calculator — for vial + BAC water reconstitution rather than pre-mixed pens.
- Reconstitution Calculator — for the underlying mg-to-mcg-per-mL conversion.
- Half-Life Calculator — for choosing the right dosing interval for the peptide in your pen.