Pick a vial strength, choose how much bacteriostatic water goes in and read the concentration and syringe units. Arithmetic only, the amount is yours to enter.
Results
0 to 100 units
Fill in the three fields on the left to calculate.
Bacteriostatic water, 10ml →Understanding units
The calculator tells you how many units to draw. Here is exactly what a unit is, and why it means the same thing on every insulin syringe.
On a U-100 insulin syringe one unit is a hundredth of a millilitre. So 10 units is 0.1 mL, and 100 units is 1 mL. Units simply make very small volumes easier to read off the barrel.
It does not matter which insulin syringe you pick up. Drawing to 20 units pulls the same 0.2 mL on a 0.3 mL, a 0.5 mL or a 1 mL syringe. The tick marks never change size.
What changes between syringes is how many of those marks fit on the barrel. A bigger syringe is not a bigger unit, it is just more room.
Example: a 20-unit draw is 0.2 mL on all three syringes above. The only difference is how much empty barrel is left behind it.
The full guide
The bacteriostatic water calculator guide
How the bacteriostatic water calculator works
Bacteriostatic water is sterile water with 0.9% benzyl alcohol, used to dissolve lyophilized peptide powder. The question this page answers is how much water goes into a vial, and the honest answer is that it is a choice with a consequence. This calculator opens on a 10mg vial with 2mL of water loaded and shows what that choice does to the concentration and the syringe reading. Change the vial strength or the water volume and every number updates.
How much bacteriostatic water for a peptide vial
There is no single correct volume for any peptide. Concentration is vial mass divided by water volume, so each extra millilitre lowers the concentration and spreads the same mass across more syringe units. Common vial strengths with common water volumes:
- 5mg vial in 1mL gives 5mg/mL, in 2mL gives 2.5mg/mL and in 3mL gives 1.67mg/mL
- 10mg vial in 1mL gives 10mg/mL, in 2mL gives 5mg/mL and in 3mL gives 3.33mg/mL
- 30mg vial in 1mL gives 30mg/mL, in 2mL gives 15mg/mL and in 3mL gives 10mg/mL
- 50mg vial in 1mL gives 50mg/mL, in 2mL gives 25mg/mL and in 3mL gives 16.67mg/mL
The practical limit is the syringe. Under 2 units on a U-100 syringe the width of a tick mark is a large share of the draw, so a small reading is a reason to add more water, not less.
Peptide reconstitution water: reading the result
Once the volume is chosen, the conversion is two divisions. Divide the amount by the concentration to get the volume in mL, then multiply by 100 for units. At 5mg/mL, 1mg is 0.2mL, which is 20 units. The calculator also shows micrograms per unit, which is the concentration in mg/mL multiplied by 10.
Check the vial and the water before you calculate
Every figure starts from the strength printed on the vial, so confirm it against the certificate of analysis for your batch. Healio publishes each one on the research page, and how to read a certificate of analysis explains which figures actually prove something. Once the vial is mixed, write the water volume, the concentration and the date on the label. Our guide to reconstituting peptides covers the handling, and how long bacteriostatic water lasts covers the in-use window. The water has a clock of its own: how long bacteriostatic water lasts sets out the in-use window, and bacteriostatic water vs sterile water covers the difference.
Bacteriostatic water for sale from Healio comes as a 10mL vial. The all-peptide calculator holds presets for every Healio compound, including BPC-157 and retatrutide.
Bacteriostatic water calculator FAQ
How much bacteriostatic water goes in a 10mg peptide vial?
It is a choice, not a fixed answer. 1mL gives 10mg/mL, 2mL gives 5mg/mL and 4mL gives 2.5mg/mL. The volume sets the concentration, which sets where an amount sits on the syringe scale.
How many mL of bac water for a 5mg vial?
Any volume works arithmetically. 1mL gives 5mg/mL, 2mL gives 2.5mg/mL and 2.5mL gives 2mg/mL. Choose the volume that keeps the syringe reading above 2 units.
Does more bacteriostatic water make a peptide weaker?
No. The mass in the vial does not change. More water lowers the concentration, so the same amount occupies a larger volume and more syringe units.
What is bacteriostatic water?
Sterile water that contains 0.9% benzyl alcohol, which resists bacterial growth and allows more than one withdrawal from the same vial. What is bacteriostatic water has the detail.
Does the calculator recommend an amount?
No. It converts the figures you enter and makes no recommendation. Healio supplies research compounds for laboratory use, so quantities belong to the protocol a researcher is working to.
Can I use it for any peptide?
Yes. The arithmetic does not change between compounds, only the vial strength does. The all-peptide calculator holds presets for every Healio compound.
Healio Peptides supplies research compounds intended for laboratory and research use only. This calculator performs concentration arithmetic on figures you enter. It does not recommend quantities, and nothing on this page is medical advice. These compounds are not intended for human consumption and these statements have not been evaluated by the FDA.