How many units is 0.1 mL?

On a U-100 insulin syringe, 0.1 mL is 10 units. Multiply mL by 100 to get units. Divide units by 100 to get mL.

What is the difference between mg and mcg?

One milligram (mg) is 1,000 micrograms (mcg). So 0.25 mg is the same as 250 mcg. Mixing them up gives a dose 1,000 times too big or too small.

Does adding more water change the dose?

No. The vial holds the same amount of peptide. More water makes each unit weaker, so you draw more units to get the same dose.

Can this calculator tell me what dose to use?

No. It only does math with the numbers you type. Only a licensed clinician should set a dose.

Calculator · U-100 insulin syringes

Peptide reconstitution calculator

Reconstitution means mixing the powder in a vial with water. Type how much peptide is in the vial, how much water was mixed in, and the dose you were told to use. See how many units to draw on a U-100 insulin syringe.

Updated November 3, 2026, by The Peptide Field Read our standards

This does the math. It does not pick a dose.

Only a licensed clinician should set a dose. Talk with your doctor, nurse, or pharmacist before you use any number from this page. Ask them to work out the numbers on their own.

You use these results at your own risk. The Peptide Field is not liable for any dose measured or taken with them.

How the math works

More water spreads the same peptide thinner.

Both vials hold the same amount of peptide. Each dot stands for a little of it.
Water spreads the dots out. More water puts more space between them.
So a draw of the same size holds fewer dots. With more water, you draw more units for the same dose.

Drawing of a vial of powder plus a vial of water making one mixed vial. — Illustration only. It is not to scale. Use the drawing in your result for your numbers.

Before you use these numbers

Have your provider check the math first. Show your doctor, nurse, or pharmacist the vial, its label, and the numbers you typed. Ask them to work it out on their own.
Check that the syringe says U-100. The FDA describes U-100 as 100 units in every mL. U-40 syringes hold 40 units in every mL, so the marks mean something else.
Use the same unit as your instructions. Mixing up mg and mcg gives a dose 1,000 times too big or too small.
Write down how much water went in the vial. You need that number each time you work out a dose.
Using a pen? Pen clicks are not syringe units. Pens come mixed and marked by the maker, so follow the pen label, not this page.
Use a new, sterile needle and syringe for every dose. Never share needles or syringes, and keep each vial for one person. The FDA and CDC both say this.
Took the wrong amount? Call Poison Help: 1-800-222-1222 It is free and open 24 hours a day, every day.

What this calculator cannot do

It cannot tell you what dose to use. Only a licensed clinician should set a dose.
It cannot check that the vial holds the amount printed on its label.
It cannot tell you if a product is safe, legal, or real.
It works only for U-100 insulin syringes. U-40 syringes are marked differently, and the result would be wrong.
It never turns IU into mg or mcg. That depends on the substance, so only the label can tell you.

Common questions

How many units is 0.1 mL?: On a U-100 insulin syringe, 0.1 mL is 10 units. Multiply mL by 100 to get units. Divide units by 100 to get mL.
What is the difference between mg and mcg?: One milligram (mg) is 1,000 micrograms (mcg). So 0.25 mg is the same as 250 mcg. Mixing them up gives a dose 1,000 times too big or too small.
Does adding more water change the dose?: No. The vial holds the same amount of peptide. More water makes each unit weaker, so you draw more units to get the same dose.
Can this calculator tell me what dose to use?: No. It only does math with the numbers you type. Only a licensed clinician should set a dose.

Sources

The calculator uses one fixed fact: on a U-100 syringe, 100 units fill 1 mL. The rest is division with the numbers you type. It names no sellers and suggests no doses.

The needle, 28-day, and Poison Help lines come from the FDA, CDC, USP, and Poison Help pages listed here.

510(k) clearance K233794: Insulin Syringe (U-40 and U-100), March 6, 2024U.S. Food and Drug Administration · Checked November 2, 2026
Quoted: “U-100 means there are 100 units of insulin in every mL”
FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight LossU.S. Food and Drug Administration · Checked November 3, 2026
Quoted: “Always use a new, sterile needle and syringe for each dose.”
Preventing Unsafe Injection Practices, March 26, 2024Centers for Disease Control and Prevention · Checked November 3, 2026
Quoted: “Never reuse a needle or syringe on more than one patient.”
Quoted: “Limit the use of multi-dose vials and dedicate them to a single patient whenever possible.”
Quoted: “the vial should be dated and discarded within 28 days unless the manufacturer states another date for that opened vial”
USP General Chapter 797 FAQs, December 11, 2023United States Pharmacopeia · Checked November 3, 2026
Quoted: “a conventionally manufactured multiple-dose vial may not be used after 28 days of first puncture”
Calling Poison HelpHealth Resources and Services Administration · Checked November 3, 2026
Quoted: “The toll-free Poison Help line is 1-800-222-1222.”
Quoted: “This number provides free and confidential help 24 hours a day, 7 days a week, 365 days a year.”