Question 1

How many units is 250 mcg on a 1mL syringe?

Accepted Answer

It depends entirely on the concentration of the solution, so 250 mcg has no single unit value. Units on a U-100 syringe measure volume: 1 unit equals 0.01 mL. As a conditional example, if a 5 mg vial is reconstituted with 2 mL of water, the concentration is 2.5 mg/mL (2,500 mcg/mL), so 250 mcg occupies 0.10 mL, which is the 10-unit mark. With 1 mL of water the same mass would be 5 units, and with 3 mL it would be 15 units. Use the calculator with your own vial mass and water volume.

Question 2

What is the difference between bacteriostatic water and sterile water?

Accepted Answer

Bacteriostatic water for injection is sterile water containing a preservative, typically 0.9% benzyl alcohol, which inhibits bacterial growth and is labeled for multiple-dose use. Sterile water for injection without a preservative is generally labeled for single use. They are not interchangeable by assumption: the right diluent depends on the specific product and its labeling, and benzyl alcohol is unsuitable in some contexts. Always follow the product label and supplier instructions.

Question 3

How do you convert mg to mcg?

Accepted Answer

Multiply milligrams by 1,000 to get micrograms, because 1 mg equals 1,000 mcg. For example, 0.25 mg is 250 mcg and 2.5 mg is 2,500 mcg. To go the other way, divide micrograms by 1,000: 500 mcg is 0.5 mg.

Question 4

How should lyophilized peptides be stored after reconstitution?

Accepted Answer

There is no universal rule. Storage temperature, light protection, and how long a reconstituted solution remains stable vary by compound, formulation, diluent, and container. Follow the supplier's or manufacturer's documented instructions and certificate of analysis for the specific product. This calculator's duration figures are arithmetic only and say nothing about stability or expiry.

Question 5

What does IU mean on an insulin syringe?

Accepted Answer

The markings on a U-100 insulin syringe are volume graduations usually labeled simply as units, where 100 units equal 1 mL and each unit is 0.01 mL. They were designed around U-100 insulin, which contains 100 insulin units per mL. These syringe units are not International Units (IU) of a peptide's biological activity and do not express potency. The mass in any given unit depends on the concentration of the solution.

Question 6

Why shouldn't you shake a reconstituted peptide vial?

Accepted Answer

Vigorous shaking can cause foaming, and for some peptides it can promote aggregation or denaturation at the air-liquid interface. The sensitivity is not universal and differs by molecule and formulation. Many handling protocols recommend gentle swirling or slow rolling instead, but the product-specific handling instructions from the supplier should take precedence.

Syringe units	Volume (mL)
5 units	0.05 mL
10 units	0.10 mL
25 units	0.25 mL
50 units	0.50 mL
100 units	1.00 mL

Mass	1 mL water5 mg/mL	2 mL water2.5 mg/mL	3 mL water≈1.667 mg/mL
100 mcg	2 units	4 units	6 units
250 mcg	5 units	10 units	15 units
500 mcg	10 units	20 units	30 units
1,000 mcg	20 units	40 units	60 units

Peptide Calculator — Reconstitution & U-100 Syringe Units

01Compound preset

02Syringe

03Vial mass

04Bacteriostatic water

05Desired dose (research)

How to Use the Peptide Reconstitution Calculator

Select vial mass (mg)

Choose water volume (mL)

Enter the research amount (mcg or mg)

Read the U-100 graduation

Peptide Dosage & Syringe Conversion Charts

Frequently Asked Questions About Peptide Math

Research supplies

Bacteriostatic water

Empty laboratory vials

Vial racks & holders

Laboratory labels

Milligrams (mg)	Micrograms (mcg)
0.1 mg	100 mcg
0.25 mg	250 mcg
0.5 mg	500 mcg
1.0 mg	1,000 mcg
2.5 mg	2,500 mcg
5.0 mg	5,000 mcg