The most accurate, and easiest-to-use Peptide Calculator on the web, giving you exact syringe units + the option to calculate the bacteriostatic water value, and one-tap peptide presets.

How to Use Peptide Calculators: Video Walkthrough

If you learn better by watching, the video below walks through the general process of using an online peptide dose calculator to reconstitute a vial and measure a dose. Note that the calculator shown in the video is a different tool from the one on this page, but the underlying method is the same: enter your vial strength, choose your water volume, set your dose, and read the units to draw. The peptide calculator at the top of this page follows the same logic, with the added benefit of one-tap presets and a true-to-scale syringe visual.

Peptide Calculator

The peptide calculator above is a free, no-sign-up tool that turns three simple inputs — your vial strength, the amount of bacteriostatic water you added, and your target dose — into the exact number of units to draw on an insulin syringe. Instead of doing reconstitution math by hand and risking a decimal-point error, you get an instant, true-to-scale syringe visual, your solution concentration, and the number of doses your vial holds. This page explains how to use the peptide calculator, how the underlying math works, and how to load a common starting setup for popular compounds with one tap.

Whether you are searching for a peptide calculator, a peptide reconstitution calculator, a peptide dose calculator, or a peptide dosage calculator, this tool does the same core job: it converts milligrams of peptide and millilitres of water into a clear, measurable draw on your syringe. As a free peptide calculator that also works as a peptide calculator mg and microgram tool, it is designed to be the best peptide reconstitution calculator available — accurate, visual, and genuinely easy to use on both desktop and phone.

How to Use the Peptide Calculator

Using the peptide calculator takes about ten seconds once your inputs are in front of you. The tool is built around four choices, laid out left to right, and it recalculates automatically every time you change one — there is no submit button to press.

Step 1 — Syringe Size. Pick the total volume of your insulin syringe: 0.3 mL, 0.5 mL, or 1.0 mL. Each option shows a small reference syringe with its own unit scale (0–30, 0–50, or 0–100 units) so you can match the physical syringe in your hand. All three use the same U-100 scale, where 100 units equals 1 mL, so a given dose is the same number of units on any of them — the only difference is total capacity and how far apart the tick marks sit.

Step 2 — Strength of Peptide. Select the total milligrams of peptide in your vial, which is printed on the label (for example 5 mg or 10 mg). Tap a preset button or type any value into the manual box. This is the amount of dry peptide in the vial before you add any water.

Step 3 — Bacteriostatic Water. Choose how much bacteriostatic water you are adding to the vial. This is the single most important number for controlling concentration: more water spreads the same peptide over more units for finer, easier measurement, while less water concentrates it into fewer units. Common volumes are 1 mL to 3 mL.

Step 4 — Dose of Peptide. Enter the dose you want per injection, in either micrograms (mcg) or milligrams (mg) using the toggle. The peptide calculator instantly shows your result as a plain sentence — “To get a dose of X, pull the syringe to Y units” — alongside a full-width syringe visual with the exact draw point marked, plus your concentration, volume per dose, and doses per vial.

Below the result you will find the Quick Presets, which load a commonly cited vial, water, and dose combination for a specific compound with a single tap. These are starting points for reference only, explained in detail further down this page.

What a Peptide Calculator Actually Does

A peptide calculator solves one specific problem: peptides are sold as a dry, freeze-dried (lyophilized) powder, but they must be dissolved in liquid before they can be measured and injected. That dissolving step is called reconstitution. Once you add a known volume of bacteriostatic water to a known quantity of peptide, every microgram of that powder is now spread evenly through the liquid — and the job of the peptide reconstitution calculator is to tell you precisely how much of that liquid equals your target dose, expressed in the units marked on an insulin syringe.

Without a peptide dose calculator, people reach for mental math or a scribbled note, and that is exactly where dangerous mistakes happen: mixing up micrograms and milligrams, forgetting that the water volume changes the units, or misreading a syringe. This peptide calculator removes that guesswork by handling the arithmetic and drawing the syringe for you, so what is left is simply matching the mark on screen to the mark on your syringe.

How the Peptide Calculator Math Works

The peptide calculator relies on three straightforward formulas. Peptide dissolves evenly in the water you add, so concentration is just the milligrams of peptide divided by the millilitres of water. Insulin syringes are marked in units, where 100 units equal 1 mL (the U-100 standard defined by the insulin syringe scale). The three calculations are:

Concentration (mg/mL) = vial mg ÷ bacteriostatic water mL
Volume to draw (mL) = target dose mg ÷ concentration
Units to draw = volume to draw mL × 100
Doses per vial = vial mg ÷ dose mg, rounded down

Here is a concrete example the peptide dosage calculator handles instantly. A 5 mg vial reconstituted with 2 mL of bacteriostatic water gives a concentration of 2.5 mg/mL, which is the same as 25 mcg per unit. A 250 mcg dose is therefore 0.10 mL, or 10 units on a U-100 syringe, and the 5 mg vial holds 20 of those doses. Change the water to 1 mL and that same 250 mcg dose becomes just 5 units — the dose has not changed, only how it is measured. That relationship between water volume and units is the single most useful thing the peptide calculator makes visible.

How to Reconstitute Your Vial

Reconstitution is the act of adding liquid — almost always bacteriostatic water — to a freeze-dried peptide so it becomes a measurable solution. Get your target dose and protocol from a licensed provider first; the peptide calculator handles the arithmetic, not the medical decision. The general process looks like this:

Clean both stoppers. Wipe the rubber tops of the bacteriostatic water vial and the peptide vial with an alcohol swab before puncturing either one.

Draw the water first. Pull the amount of bacteriostatic water you entered into the peptide calculator into your syringe before touching the peptide vial.

Add the water slowly. Aim the stream down the inside glass wall of the peptide vial rather than blasting it directly onto the delicate powder.

Swirl gently. Roll or swirl the vial until the powder fully dissolves. Never shake it hard, as agitation can damage the peptide.

Store correctly. Keep the reconstituted vial refrigerated and protected from light unless your provider or the product labeling specifies otherwise.

A Worked Example Using the Peptide Calculator

Suppose your vial reads 5 mg, you plan to add 3 mL of bacteriostatic water, and your target is a 250 mcg dose. Enter each value into the peptide calculator: set Strength of Peptide to 5 mg, Bacteriostatic Water to 3 mL, and Dose of Peptide to 250 mcg. Behind the scenes, 5 mg equals 5,000 mcg dissolved in 3 mL, which gives a concentration of about 1.67 mg/mL. To get 250 mcg from that solution you need to draw roughly 0.15 mL, which on a U-100 insulin syringe is 15 units. The peptide dosage calculator shows this as “pull the syringe to 15 units” and marks that exact point on the syringe visual, so you can see as well as read where to stop.

This is why the water volume matters so much. If you had used 2 mL of water instead of 3 mL, the same 250 mcg dose would work out to 10 units, not 15. The peptide calculator lets you try different water volumes in seconds to find a draw that lands on an easy-to-read mark on your particular syringe.

Quick Presets: Common Starting Setups by Compound

The Quick Presets under the result load a commonly cited vial, water, and dose combination for popular compounds into the peptide calculator with one tap. Each is a widely referenced starting point, not a personal recommendation — and crucially, a preset only fills the vial strength, water, and dose. You still need to confirm you have selected the correct syringe size and that the dose matches what your own provider has set. Always verify against your protocol before drawing anything.

Semaglutide. A common starting setup is a 5 mg vial with 2 mL of water at a 0.25 mg (250 mcg) weekly dose. The 0.25 mg starting dose reflects the titration schedule in the Wegovy prescribing information. You can use this peptide calculator as a semaglutide dosage calculator by loading this preset, then adjusting the dose as your provider escalates it. Learn more about the molecule at Wikipedia’s semaglutide entry.

Tirzepatide. A common setup is a 10 mg vial with 2 mL of water at a 2.5 mg weekly starting dose. That 2.5 mg initiation dose comes directly from the FDA Zepbound prescribing information and the SURMOUNT trial program. To use this as a tirzepatide dosage calculator, load the preset and confirm your syringe size before drawing. Background reading is available via the tirzepatide Wikipedia article.

Retatrutide. A frequently cited research setup is a 10 mg vial with 2 mL of water at a 2 mg dose, though trials began far lower, at 0.5–1 mg per week, with gradual escalation. Retatrutide is investigational and not approved for any use; the New England Journal of Medicine phase 2 trial is the primary source. Use this peptide calculator as a retatrutide calculator by loading the preset and titrating slowly.

BPC-157. A common protocol is a 5 mg vial with 2 mL of water at 250 mcg once or twice daily. BPC-157 is a research peptide not approved for human use; see the BPC-157 overview for context. Confirm your intended dose lands on a readable syringe mark before you draw.

TB-500. A common loading setup is a 5 mg vial with 2 mL of water at a 2.5 mg dose once or twice weekly for the first several weeks. TB-500 is a synthetic fragment related to thymosin beta-4. Because this is a larger dose, double-check whether it fits your chosen syringe size in the peptide calculator.

Ipamorelin. A common setup is a 5 mg vial with 2 mL of water at 200–300 mcg per injection, often dosed at bedtime. Ipamorelin is a growth-hormone secretagogue; read more at its Wikipedia entry. It is frequently paired with CJC-1295.

CJC-1295. A common setup is a 5 mg vial with 2 mL of water at 100–300 mcg per injection. CJC-1295 is a GHRH analog often combined with ipamorelin in the same syringe. When stacking, remember the peptide calculator handles one compound at a time.

GHK-Cu. A common setup is a 5 mg vial with 2 mL of water at roughly 200 mcg per injection. GHK-Cu is a copper peptide studied for skin and connective-tissue research. As always, confirm the dose and syringe size before drawing.

Peptide Dosing Chart

If you prefer to look up common combinations at a glance rather than enter them one by one, we maintain a full peptide dosing chart that lists typical vial sizes, water volumes, resulting concentrations, and example doses in units for many popular compounds. The chart pairs naturally with this peptide calculator: use the chart to find a reference setup, then load those numbers into the tool above to see the exact syringe draw and doses per vial for your specific vial. Together, the peptide dosing chart and the peptide calculator cover both quick reference and precise, personalized calculation.

Choosing the Right Syringe Size

One of the most common questions this peptide calculator answers is which insulin syringe to use. The three standard barrel sizes — 0.3 mL (30-unit), 0.5 mL (50-unit), and 1.0 mL (100-unit) — all use the identical U-100 scale, where 1 unit equals 0.01 mL. That means a given dose is the same number of units on any of them; only the total capacity and the spacing between tick marks differ. A smaller barrel spreads a small dose across more physical length, making the tiny lines easier to read accurately. If your calculated draw is small, say under 20 units, a 0.3 mL syringe will make it easier to measure precisely. If you are not sure which to pick, the 1.0 mL syringe is the safe default because it fits every dose the peptide calculator is likely to produce.

Dedicated Calculators for Specific Compounds

This general peptide calculator works for every compound — you simply load the matching Quick Preset or enter your own numbers. For people who search for a specific branded tool, we also build dedicated pages that pre-configure the calculator for one compound, including a tirzepatide dosage calculator, a retatrutide dosage calculator, and equivalents for semaglutide, BPC-157, TB-500, ipamorelin, CJC-1295, and GHK-Cu. Each dedicated calculator uses the same trusted engine as the peptide calculator here, so whichever page you land on, the math and the syringe visual are identical. If you already know your numbers, there is no need to visit a separate page — the tool above handles all of them.

Important Disclaimer

This peptide calculator is provided for research and educational purposes only. It performs a mathematical conversion — it does not set your dose, confirm that any peptide is safe, appropriate, or legal for you, or replace the judgment of a qualified professional. Many peptides discussed here are not approved for human use. Always obtain your target dose and full protocol from a licensed physician or pharmacist, double-check every number the calculator produces yourself, and speak to your doctor to confirm your doses before drawing or administering anything. Never rely on a single online tool for a health decision.

Peptide Calculator FAQ