Bench

Reconstitution calculator

Work out how much water to add and how far to draw the plunger. The syringe below is drawn to the real proportions of the barrel you pick, so you can hold yours against the screen.

Which syringe are you holding?

1 mark = 0.01 mLbarrel reads 0 to 50marks every 1

The usual choice for peptide volumes.

Check the barrel before you trust a number
A U-40 barrel numbered 0 to 40 and a U-100 barrel numbered 0 to 100 look similar, but one mark is 0.025 mL on U-40 against 0.01 mL on U-100. Reading a U-40 barrel as though it were U-100 delivers 2.5 times the intended dose. There is no such thing as a 0.4 mL U-100 syringe, so a “40 unit syringe” is most likely the 1 mL veterinary U-40 barrel.

The vial and the dose

Fills in a typical vial size and dose.

mg
mL

Bacteriostatic water for a multi-dose vial.

mcg

Draw to here

10203040
Volume
0.1mL
The primary answer.
U-100 marks
10
On the 0 to 100 scale.
Concentration
5mg/mL
50 mcg per mark.
Doses per vial
20
At 500 mcg each.
The same 0.1 mL reads as4marks on a U-40 barrel.

Water volumes that read more cleanly

Same vial, same dose, different amount of water. A draw that lands exactly on a printed mark is one you can repeat accurately every time.

How this is worked out

concentration = 10 mg ÷ 2 mL = 5 mg/mL

volume = 500 mcg ÷ 5 mg/mL = 0.1 mL

marks = 0.1 mL ÷ 0.01 mL per mark = 10

The lyophilised powder itself displaces roughly 0.7 microlitres per milligram, so a 10 mg vial shifts a 2 mL reconstitution by about 0.35%, well under the finest mark on any barrel. It is ignored here, as it is in clinical practice.

The arithmetic here is exact and tested. What it cannot check is whether the vial holds what the label says, unregulated material has no verified identity, purity or sterility, and correct maths on an unverified product does not make it safe. Nothing in this app is medical advice.