Skip to content
Homepage
Free · Private · Published formula

Peptide Dosage Calculator: Prescribed mcg to Syringe Units

Your prescriber gave you a dose in micrograms. A syringe has no microgram markings, so the figure has to be translated before the first injection. Enter the dose, then the vial strength and the water that went in, and the page returns the milliliters and the U-100 units that hold exactly those micrograms, plus how many doses the vial covers.

  • Calculator
  • About 3 min
  • Dimensional analysis (Boyer 2016), U-100 syringe convention
  • Runs in your browser, nothing is sent
  • Medical review: Medical review pending
Open the calculator

What this calculator works out

A prescription says how many micrograms to inject. A syringe is marked in units of volume. The bridge between them is the concentration of your particular vial, and that bridge is all this page builds: a unit conversion for a dose a prescriber has already decided.

  1. 1

    Units to draw

    The headline number: how many units on a U-100 insulin syringe hold the prescribed micrograms at your vial's concentration. It is shown to one decimal so you can see which way to round to the nearest mark on your syringe.

  2. 2

    The same dose as a volume

    Milliliters per dose, with the concentration that produced it. Pharmacists and prescribers usually talk in milliliters, so this is the number to read back to them when you confirm what you were told to draw.

  3. 3

    Whether one vial covers the schedule

    The vial's micrograms divided by your prescribed dose, rounded down. Read against the frequency on the prescription, it tells you how many weeks a vial covers and whether the last dose would fall after the beyond-use date on the label.

How this compares with a typical online quiz

FeatureTypical free quizRegenerated.com
Starts from the prescribed doseSometimesYes; the dose is the first field and comes only from you
Preloaded doses by peptide nameCommonNone; a built-in dose would be a dose suggestion
Formula and worked example shownRarelyYes, on the result page
Flags a volume the syringe cannot measureNoYes, with the mg and mcg check that usually explains it
Sells or links to peptidesOftenNever; no products, no sourcing
Answers sent to a serverOftenNever; scored in your browser, counts-only events

Why mcg to units has no fixed conversion

People search for an mcg-to-units conversion as if it were like inches to centimeters. It is not, because a unit on an insulin syringe is a volume (0.01 mL) and a microgram is a weight. How many micrograms sit in 0.01 mL depends entirely on how concentrated the solution is, and that depends on how much peptide was in the vial and how much water went in. The same 200 mcg dose is 20 units from a vial at 1,000 mcg/mL, 8 units at 2,500 mcg/mL and 4 units at 5,000 mcg/mL.

This is why every conversion needs three numbers and why a chart that lists units next to a peptide name without stating the concentration cannot be trusted. The arithmetic is: concentration in mcg/mL equals vial milligrams times 1,000 divided by milliliters of water; milliliters per dose equals dose in mcg divided by concentration; units equal milliliters times 100. Dividing the vial's micrograms by the dose gives the number of full doses in the vial. All of it is in the method note on the result page with a worked example.

Reading the prescription and the label

A compounded peptide prescription states the peptide, the strength of the vial, the dose, the route and the frequency. The dose may be written in micrograms (mcg or µg) or milligrams (mg); 1 mg is 1,000 mcg, so a 0.25 mg dose is 250 mcg and a 2 mg dose is 2,000 mcg. The calculator takes micrograms only, so convert first. The pharmacy label on a vial reconstituted by the pharmacy states the concentration in mcg/mL or mg/mL and a beyond-use date; a 2.5 mg/mL label means 2,500 mcg/mL. If you reconstituted the vial yourself, the concentration is whatever your vial strength and water volume make it, and the label will show only the dry strength.

Two checks catch most errors. First, the units on the result should agree with what the prescriber or pharmacist told you to draw; if they differ, one of the three inputs is wrong, and the most common culprit is a dose typed in mg instead of mcg. Second, the doses-per-vial figure should match how long the pharmacy said a vial would last. When either check fails, stop and call the pharmacy rather than drawing a dose that feels approximately right.

What the calculator will not do, and the regulatory background

The calculator holds no dose for any peptide, offers no defaults that imply one, and does not compute schedules, cycles or titration. It cannot, because dosing is a prescribing decision that depends on the compound, the indication, your weight, your kidneys and liver, your other medicines and the evidence, and because much of the peptide market has little human dosing evidence to draw on. Any number entered in the dose field is treated as a prescription you already hold.

Regulatory status differs by compound and matters for what a clinic can legitimately offer. Tesamorelin (marketed as Egrifta) is FDA-approved for abdominal fat in HIV-associated lipodystrophy and bremelanotide (marketed as Vyleesi) for hypoactive sexual desire disorder in premenopausal women; other uses of either are clinician-directed off-label prescribing. Many peptides sold in clinics have no FDA approval for any indication and reached patients only through compounding. Section 503A lets a pharmacy compound from a bulk substance only if that substance has a USP or NF monograph, is a component of an FDA-approved drug product, or appears on the 503A bulks list. In September 2023 the FDA placed several peptides, BPC-157 among them, in 503A category 2 for significant safety risks; its 503A category list updated April 22, 2026 removed twelve of those peptides, BPC-157 among them, from category 2 because the nominations were withdrawn by the nominators, and its safety-risk page, current as of April 22, 2026, lists them among the withdrawn nominations with the safety concerns still set out. We checked both on October 8, 2026. A withdrawn nomination is a decision by whoever nominated the substance, not an FDA finding that the substance is safe, and none of those peptides went onto the 503A bulks list. On those FDA pages as they stood on April 22, 2026, which we read on October 8, 2026, none of them was a substance a US pharmacy could compound from bulk. The FDA consulted its Pharmacy Compounding Advisory Committee on July 23 and 24, 2026 about adding seven of them, having proposed in its own briefing document that none be included; that advice is non-binding and the agency had not acted on it as of October 8, 2026. The lists are revised over time, so read the FDA's own pages and the content-current-as-of date each one carries, and a clinic should be able to tell you where its peptides stand.

Methodology and sources

The page uses the dimensional-analysis method of every dosage-calculation text, following Boyer's Math for Nurses (9th edition, 2016), applied to a lyophilized vial that has already been reconstituted. Its job is the one a prescription creates: a dose written in micrograms has to become a mark on a syringe, so the dose is the first field and everything else is read in support of it. Deciding how much diluent to add is a separate question, answered on the peptide reconstitution calculator, and working from the vial downward when the dose is already in hand is the job of the general peptide calculator. The engine prints a fixed line above the inputs and the result: this is arithmetic for a dose your clinician prescribed and it is not a recommendation. Nothing on the page changes that.

Concentration (mcg/mL) = vial mg x 1,000 / water mL. Volume (mL) = dose mcg / concentration. Units on a U-100 syringe = mL x 100. Doses per vial = vial mg x 1,000 / dose mcg, rounded down. Worked example from the prescription side: a dose of 1,000 mcg, which is how a 1 mg prescription converts, filled from a 10 mg vial that took 2 mL of bacteriostatic water. The vial holds 10,000 / 2 = 5,000 mcg/mL, so the dose is 1,000 / 5,000 = 0.2 mL, which is 20 units on a U-100 syringe, and the vial covers 10,000 / 1,000 = 10 doses. The formula registry's own example runs the smaller case and agrees: a 5 mg vial with 2 mL is 2,500 mcg/mL, a 250 mcg dose is 0.1 mL or 10 units, and that vial holds 20 doses.

The limits are those of the inputs and the syringe. The arithmetic assumes an accurate vial label, complete dissolution, that all of the stated water went into the vial, and a U-100 syringe. It ignores the dead space in a syringe hub and any peptide left on the vial wall, both of which are small. Results are shown to one decimal of a unit for rounding direction only; draw to the nearest mark your syringe has, and when a dose lands under about 5 units ask the prescriber or pharmacist about a more dilute vial rather than trying to read a fraction of a mark.

Medical review: Medical review pending. Last updated .

References

  1. Boyer MJ. Math for Nurses: A Pocket Guide to Dosage Calculation and Drug Preparation. 9th ed. Philadelphia, PA: Wolters Kluwer; 2016.
  2. United States Pharmacopeia. General Chapter 797: Pharmaceutical Compounding, Sterile Preparations. Rockville, MD: USP; revised 2023. https://www.usp.org/compounding/general-chapter-797
  3. US Food and Drug Administration. Certain bulk drug substances for use in compounding that may present significant safety risks. Content current as of April 22, 2026; checked October 8, 2026. https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
  4. Institute for Safe Medication Practices. ISMP Guidelines for Optimizing Safe Subcutaneous Insulin Use in Adults. Horsham, PA: ISMP; 2017. https://www.ismp.org/guidelines/subcutaneous-insulin
  5. US Food and Drug Administration. Bulk drug substances nominated for use in compounding under section 503A of the Federal Food, Drug, and Cosmetic Act, category list updated May 14, 2026 (and the April 22, 2026 version recording the withdrawn nominations), with the FDA briefing document for the Pharmacy Compounding Advisory Committee meeting of July 23 and 24, 2026. Checked October 8, 2026. https://www.fda.gov/media/94155/download and https://www.fda.gov/media/193342/download

Peptide Dosage Calculator: Prescribed mcg to Syringe Units FAQ

Work out the vial's concentration first (vial mg x 1,000 / water mL), divide the dose in mcg by that concentration to get mL, then multiply by 100 for units on a U-100 syringe. For example 250 mcg from a 2,500 mcg/mL vial is 0.1 mL, which is 10 units. There is no shortcut that skips the concentration, because units measure volume and micrograms measure weight.

From your prescription. The page has no dose built in for any peptide and no default in the dose field. If you do not have a prescribed dose written in mcg or mg, the calculator has nothing to convert, and the question of how much to use belongs with a prescriber who knows the compound, the evidence and your history.

500. Multiply milligrams by 1,000 to get micrograms: 0.1 mg is 100 mcg, 0.5 mg is 500 mcg, 2 mg is 2,000 mcg. Typing 0.5 in the mcg field would give a volume a thousand times too small, so this is the check to make before anything else.

They share the arithmetic and answer three different questions. This page starts from the dose, for someone holding a prescription in micrograms. The peptide calculator starts from the vial and answers how much liquid to draw now. The peptide reconstitution calculator holds the vial and the dose steady and asks what to add and what a single unit then contains, which is the question before a vial is mixed.

Ask the prescriber or the pharmacy to put it in micrograms in writing. Units and milliliters only mean something against a stated concentration: 10 units is 0.1 mL, which is 250 mcg from a vial at 2,500 mcg/mL and 500 mcg from one at 5,000 mcg/mL. If a vial is reconstituted differently from the one the instruction was written for, the same mark delivers a different dose, which is the error this page exists to prevent.

Yes. Your answers and the numbers you enter are scored in your browser and are never sent to us. They stay in this browser tab so you can return to your result, and closing the tab clears them. The only thing the page sends us is a counts-only event: which test was started or completed, the result band and the headline number, with no answers, no entered values and no account. There is nothing to sign up for.

Ask a prescribing clinic the questions this page cannot answer

Browse US clinics offering peptide therapy. The dose, the compound and the schedule are prescribing decisions, so look for profiles that name the prescribing physician, write the dose in micrograms, say which licensed pharmacy fills it, repeat labs during treatment and explain the evidence before prescribing. A listing on Regenerated.com is not an endorsement.

Browse peptide therapy clinics

A listing is not a treatment endorsement. Read each clinic's published checks and talk to your clinician before starting any treatment.

Important: This page is a unit conversion on figures you type in. It takes a dose a licensed clinician has already prescribed and shows the volume and the syringe mark that hold it; it stores no dose for any peptide, offers none, and is not medical advice. Peptide products differ widely in approval status, in compounding status and in the evidence behind them. The prescription and the pharmacy label are the authorities, and anything that does not match them is a reason to call the pharmacy rather than to inject. If your symptoms are severe or sudden, seek urgent medical care.