Peptide Dosing,made clear.

The basics are simple: strength, liquid volume, concentration and target amount. Choose the tool that matches what you actually have in front of you.

Arithmetic only — not a dose recommendation.

These tools convert numbers you already know. They do not choose a target amount. For pens, you must also confirm the exact device type and click/dose-selector system; for vials, confirm concentration and syringe type before converting between mg, mL and syringe units.

Important if you are using a pen

Using a peptide pen? Start here.

Do not guess the device, click scale or technique from appearance. Watch the pen guide and confirm the exact device before using click calculations.

Watch: how to use a peptide pen Learn dosing & calculations

Choose your format

The basic idea

Same pen volume. Different strength.

Cartridge

3 mL

total

40 mg

scale

320

Three separate numbers

3 mL: the cartridge liquid volume
40 mg: the total peptide in this example pen
320 clicks: the click scale used by the current Pep Report pen model

Important distinction

The click count is a volume setting, not a universal mg setting.

A 10 mg pen and a 40 mg pen can both contain 3 mL of liquid and use the same 320-click scale. The amount represented by each click changes because the concentration changes.

How this pen type works

Twist the end

Turn the dose dial to the number of clicks you are checking.

Set the clicks

On the Pep Report reference model, each mechanical click advances a fixed fraction of the cartridge. Another pen may use a different mechanism or scale.

Push the end back in

Once the dial is set, the device mechanism delivers the selected volume through the needle.

Reset for the next use

The dial returns as the mechanism is pressed. Follow the instructions supplied with the specific device.

Pen calculator

Work out the clicks.

First confirm the device. This calculator only applies to the current Pep Report reusable 3 mL cartridge dial-a-dose reference model. Then enter the known total peptide amount and the known target amount; the calculator converts that amount into the nearest whole click.

1. Confirm your device

What type of pen do you have?

Confirm the device with the vendor before calculating

Do not transfer click counts, cartridge assumptions or priming instructions from another device. Confirm the exact pen with the vendor or manufacturer first.

Ask the vendor/manufacturer for the cartridge volume, concentration, click or dose-selector system, needle compatibility and device instructions.

Pep Report reference pen model

3 mL cartridge · 320-click scale

Use this calculator only when the actual device matches this click scale. Pen body labels such as 60-unit or 80-unit do not change the calculation used here.

2. Mg of peptide in pen

3. Mg of known target amount

Enter an amount only when you already have it from a study, product instructions or a qualified clinician. The calculator does not choose a dose.

Clicks needed

—

Enter the pen strength and desired amount to calculate the nearest whole click.

Are these all the types of injector?

No. They cover the common pen workflows relevant to this calculator. Medical injectors also include jet, on-body and electronic systems. We do not provide a generic calculation for those devices. Prefilled multi-dose pens are product-specific, and a single-dose autoinjector normally has no click calculation at all.

FDA injector overview

Device confirmation is part of the calculation.

Two pens can look similar while using different cartridge volumes, concentration, dose selectors or click scales. Confirm the exact device with the vendor or manufacturer before using click math. If the pen type is unknown, do not estimate from appearance.

Check vendor pen/device information

How to use a pen

How to use a peptide pen, step by step.

Once the dose and click calculation make sense, use this section for the physical pen technique. The exact device instructions always take priority.

First: identify your pen

This guide is written for dial-a-dose pens with replaceable pen needles.

The Pep Report's click calculator is specifically built around the current reusable 3 mL cartridge dial-a-dose reference model. Do not use its click math for a single-dose autoinjector, an unknown pen, or a different click scale.

Reusable cartridge dial-a-dose pen

Recommended delivery device

A reusable pen body accepts a replaceable liquid cartridge, uses a replaceable pen needle and delivers a mechanically selected amount through a dose dial/click mechanism.

Prefilled multi-dose dial-a-dose pen

Use device-specific instructions

The medicine reservoir is built into a disposable multi-dose pen. The dose selector and priming steps are specific to that product.

Single-dose autoinjector

Click calculator not applicable

A fixed-dose device delivers one pre-set dose. There is normally no user click calculation and the Pep Report click calculator does not apply.

Unknown or another pen type

Use device-specific instructions

Do not transfer click counts, cartridge assumptions or priming instructions from another device. Confirm the exact pen with the vendor or manufacturer first.

Preferred vendor device format confirmed

Our preferred vendor currently lists compatible 3 mL cartridge products with a pen option and cartridge-only replacements. That matches the delivery device family recommended here. The exact click scale supplied still needs to be confirmed from the actual product instructions.

View preferred vendor device verification

Before using any pen calculation

Confirm with the vendor or manufacturer: the exact pen type, cartridge volume, concentration, click scale or dose-selector system, compatible needle, priming steps, hold time, storage conditions and shipping temperature requirements. If any of those are unclear, stop and get the device instructions before calculating.

Open the Mayo Clinic video Understand mg, mcg, mL & units Open the pen calculator

Before you inject: understand the number first.

Pen technique answers “how do I use the device?” It does not answer “what dose should I use?” Learn the units and source of the dose first, then use the calculator only to convert a known instruction into the pen format.

Why pens can reduce handling errors

Fewer manual steps can mean fewer opportunities to mis-measure.

With a compatible dial-a-dose pen, the user does not have to reconstitute a powder, calculate a fresh concentration, withdraw liquid from a vial and read a syringe scale for every administration. In a controlled insulin-device study, the prefilled pen was easier to use for insulin-naive participants and produced more accurate test doses than vial-and-syringe delivery.

FDA has also documented serious errors with compounded semaglutide vials when people confused milligrams, milliliters and syringe “units”; reported overdoses included amounts five to 20 times the intended dose.

FDA dosing-error alert Pen vs vial accuracy study

What vials still do well

Vials can be flexible, transparent and useful when the user understands the math.

A vial can make the total amount and chosen reconstitution volume explicit, can allow flexible concentrations, and may suit research workflows that deliberately control dilution and measurement. The trade-off is that the user takes responsibility for more preparation and measurement steps.

Pens remove some of that handling complexity, but they add a different dependency: you must trust the vendor's cartridge concentration, device specification, sterility controls, storage and cold-chain handling. A convenient pen from an unverified source is not automatically the safer choice.

Explain it simply

1
Wash your hands and check the pen label. Make sure it is the right product and not expired.
2
Attach a fresh pen needle. Use a new needle each time.
3
Prime the pen exactly the way that pen's instructions tell you to. Priming checks that the pen and needle are flowing correctly.
4
Set only the dose you were instructed to use. The Pep Report can help with arithmetic, but it does not choose the dose for you.
5
Choose an approved subcutaneous injection site for that product and rotate sites instead of using the same spot repeatedly.
6
Hold the pen straight against the skin at about 90 degrees, then insert the needle.
7
Press the injection button all the way and keep the pen in place for the time stated in that pen's instructions.
8
Pull the pen straight out. Remove the used needle and place it in a sharps container. Store the pen according to its own instructions.

This video demonstrates standard dial-a-dose insulin-pen technique and is useful for the general mechanics of a pen with a replaceable needle. It is not a device-specific manual for every peptide pen. Reusable cartridge pens may add cartridge-loading steps, while single-dose autoinjectors work differently. The instructions for the exact device in your hand always take priority.

One pen, one person. New needle every time.

CDC guidance for medication pens is explicit that pens and cartridges should not be shared between people, even when the needle is changed. Use a fresh compatible needle for each injection and dispose of used needles in an appropriate sharps container.

CDC injection-safety guidance

Does body size change the amount?

Sometimes. But there is no universal peptide rule based on height or weight.

Some approved medicines use fixed amounts. Others explicitly use body weight, such as mg/kg, or body-surface area, which can use both height and weight. Height by itself is not a general dosing rule.

The Pep Report therefore never scales a target amount automatically from body size. If a study, prescribing label or qualified clinician uses a weight- or BSA-based method, start with that known amount and use our calculator only for the arithmetic conversion.

FDA guidance on weight/BSA-based dosing

Reference cards

Common research reference ranges.

These cards put The Pep Report’s research reference amounts and schedules in one place. They are educational references rather than individualized recommendations. Open a peptide to see the evidence, formulation context and detailed dosing notes behind the number.

Human component data · combination unproven