Reconstitution calculator
How many units to draw, from your vial and your water.
Enter what’s on your vial label, how much bacteriostatic water you added, and the amount you need to measure. You get the concentration, mcg per unit, and the units on a 100-unit insulin syringe, with the working shown.
On a 100-unit (1 mL) insulin syringe
Draw to 10 units
= 0.1 mL
The math, in three steps
Concentration
vial mg ÷ water mL = mg/mL
5 mg ÷ 2 mL = 2.5 mg/mL
One unit
mg/mL × 10 = mcg per unit
2.5 × 10 = 25 mcg per unit
Your draw
amount mcg ÷ mcg per unit = units
250 ÷ 25 = 10 units
1 mg = 1,000 mcg. On a U-100 syringe, 100 units = 1 mL, so 1 unit = 0.01 mL.
mcg per unit, every common vial
How much one unit holds after mixing. Divide your amount (in mcg) by the number in your cell to get units.
| Vial | 1 mL water | 2 mL water | 3 mL water |
|---|---|---|---|
| 2 mg | 20mcg / unit · 2 mg/mL | 10mcg / unit · 1 mg/mL | 6.7mcg / unit · 0.67 mg/mL |
| 5 mg | 50mcg / unit · 5 mg/mL | 25mcg / unit · 2.5 mg/mL | 16.7mcg / unit · 1.67 mg/mL |
| 10 mg | 100mcg / unit · 10 mg/mL | 50mcg / unit · 5 mg/mL | 33.3mcg / unit · 3.33 mg/mL |
| 15 mg | 150mcg / unit · 15 mg/mL | 75mcg / unit · 7.5 mg/mL | 50mcg / unit · 5 mg/mL |
| 20 mg | 200mcg / unit · 20 mg/mL | 100mcg / unit · 10 mg/mL | 66.7mcg / unit · 6.67 mg/mL |
| 30 mg | 300mcg / unit · 30 mg/mL | 150mcg / unit · 15 mg/mL | 100mcg / unit · 10 mg/mL |
Common questions, answered with tables
Do it once. Let the app remember it.
Peptide Vault saves the math with the vial, so next week’s draw is already worked out, logs each dose, and reminds you on your schedule. iPhone, on-device.
FAQ
How do I work out how many units to draw?
Divide the vial’s contents (mg) by the water you added (mL) to get the concentration in mg/mL. Multiply by 10 to get mcg per unit on a 100-unit (1 mL) insulin syringe. Divide the amount in mcg by mcg per unit. Example: 5 mg in 2 mL is 2.5 mg/mL, or 25 mcg per unit, so 250 mcg is 10 units.
What is a U-100 insulin syringe?
A syringe marked in units where 100 units equal 1 mL, so 1 unit is 0.01 mL. Most 1 mL, 0.5 mL and 0.3 mL insulin syringes are U-100; the smaller ones simply hold 50 or 30 units.
Does adding more water change the amount in the vial?
No. Water changes the concentration, not the total. More water makes each unit weaker, so the same amount takes more units; less water makes each unit stronger.
Why does my calculator answer differ from a chart I found?
Charts assume a specific vial size and water volume. If yours differ, the units differ. Always calculate from your own vial label and the exact volume you added.
Does Peptide Vault tell me how much to take?
No. This page only does arithmetic on the numbers you enter. Amounts should come from the clinician or pharmacist responsible for your medication.