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This free peptide pen click calculator turns a dose in mg or mcg into clicks on a reusable 3 mL cartridge pen. Enter the cartridge strength or the vial you reconstituted, the mL each click delivers (from your device instructions), and your target dose. It returns the concentration, mg per click, clicks per dose with rounding error, the equivalent mL and U-100 units, and doses per cartridge. It has no brand or peptide presets and is arithmetic only, not medical advice.
clicks = dose (mg) ÷ (concentration (mg/mL) × mL per click). Clicks are rounded to the nearest whole click. Arithmetic only, not medical advice. Updated Sep 13, 2026.
| Concentration | mg per click | mcg per click | Clicks per 1 mg |
|---|---|---|---|
| 1 mg/mL | 0.01 | 10 | 100 |
| 2 mg/mL | 0.02 | 20 | 50 |
| 2.5 mg/mL | 0.025 | 25 | 40 |
| 5 mg/mL | 0.05 | 50 | 20 |
| 10 mg/mL | 0.1 | 100 | 10 |
mg per click = concentration × mL per click. A 3 mL cartridge at 0.01 mL per click holds 300 clicks in total.
| Dose | 1 mg/mL | 2 mg/mL | 2.5 mg/mL | 5 mg/mL | 10 mg/mL |
|---|---|---|---|---|---|
| 0.1 mg (100 mcg) | 10 | 5 | 4 | 2 | 1 |
| 0.25 mg (250 mcg) | 25 | 12.5 | 10 | 5 | 2.5 |
| 0.5 mg (500 mcg) | 50 | 25 | 20 | 10 | 5 |
| 1 mg (1,000 mcg) | 100 | 50 | 40 | 20 | 10 |
| 2 mg (2,000 mcg) | 200 | 100 | 80 | 40 | 20 |
| 2.5 mg (2,500 mcg) | 250 | 125 | 100 | 50 | 25 |
| 5 mg (5,000 mcg) | 500 | 250 | 200 | 100 | 50 |
Clicks = dose ÷ (concentration × mL per click). Amber values exceed 60 clicks, a common single-setting dial maximum, so that combination needs a different concentration or cannot be set in one dial. Fractional clicks cannot be dialed; the calculator above rounds and reports the error.
What is one click on a peptide pen?
On most reusable 3 mL cartridge pens, one click advances the plunger by 0.01 mL, which is 1/300th of the cartridge, so a full cartridge is 300 clicks. The mass in that click depends entirely on the concentration loaded. Increments are device-specific, so confirm the mL per click in your pen's instructions for use before relying on any click count.
Are pen clicks a labeled dosing scale?
No. On a branded prefilled pen the dose counter is the manufacturer-validated scale, and clicks are not labeled or tested as a dosing method. ISMP reported on January 6, 2025 that Novo Nordisk does not recommend counting clicks to measure doses. Clicks-per-dose figures published by vendors and forums are community-derived, so treat them as unverified arithmetic rather than labeling.
How many clicks is 1 mg?
It depends on the concentration and your pen's click size, because clicks equal dose divided by concentration times mL per click. With your current inputs, 3.333 mg/mL at 0.01 mL per click, 1 mg is 30 clicks, rounded to 30. At 5 mg/mL and 0.01 mL per click it is 20 clicks; at 2 mg/mL it is 50.
Why did the FDA warn about mL, mg and units confusion?
In July 2024 the FDA issued an alert after patients and clinicians confused milligrams, milliliters and syringe units when measuring compounded semaglutide from vials, with reported overdoses of 5 to 20 times the intended amount. Clicks add another unit that is easy to mix up, so this calculator shows mg, mL and U-100 units together for every result.
Sources: ISMP on counting pen clicks (January 6, 2025); FDA alert on dosing errors with compounded injectable semaglutide (July 2024). Compounded semaglutide and tirzepatide cartridges are not FDA-approved products. This calculator does not recommend a dose, a device, or a product.
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Frequently asked questions
How do I find the mL per click for my pen?
Check the device’s instructions for use (IFU). Most reusable 3 mL cartridge pens advance 0.01 mL per click, which is 300 clicks per cartridge, but increments vary by device. The 0.01 mL default in the calculator is editable, so match it to your pen before reading any result.
Does this work for brand-name prefilled pens?
No. Brand-name prefilled pens have a manufacturer-validated dose counter, which is the only labeled way to set a dose, and their makers do not recommend counting clicks. This calculator has no brand presets and is meant for reusable cartridge pens where you know the concentration and the mL per click.
What does the rounding error mean?
Clicks are whole numbers, so the calculator rounds the exact click count to the nearest click and shows how far the delivered amount lands from your target as a percentage. A large error means that concentration and click size cannot hit your dose precisely; a different concentration reduces it.
What are priming clicks?
Priming clicks are the clicks you dial and expel before an injection to clear air and confirm the pen is flowing. Enter the number your device instructions specify. The calculator adds them to every injection when it estimates how many doses one cartridge provides.
Is this calculator medical advice?
No. It is arithmetic and reference only. It does not recommend a dose, a device, or a product, and it does not assess whether any dose is appropriate for you. Compounded semaglutide and tirzepatide cartridges are not FDA-approved products. Verify with a clinician, a pharmacist, or the product label.