Peptide Reconstitution Calculator
Reconstitution sounds technical. It is just adding water to a powder, and the only real decision is how much. This calculator makes that decision for you in either direction: give it the water and get the draw, or give it the draw you want and get the water.
Units measure volume, not dose. The same units on a different mix are a different dose.
The link holds only the numbers you typed. No account, no tracking, nothing else.
Does more water weaken it?
No, and this question causes more confusion than any other, so it is worth being blunt. The amount of peptide in the vial never changes. Water only decides how spread out it is.
Think of it like cordial. A strong mix and a weak mix from the same bottle hold the same total amount. You just drink a bigger glass of the weak one to get the same strength. Here, the "glass" is your draw. Double the water and the same dose takes double the units. The dose itself has not moved by a single microgram.
What the water amount does change is whether your draw is practical. Too much water and a big dose will not fit in the syringe. Too little and the draw is a sliver you cannot read. Choosing the water is choosing where between those two problems you want to sit.
Water amounts for a 250 mcg dose
If your dose is 250 mcg, here is the water that puts it exactly on a round, readable draw, for the two vial sizes it usually comes in. The numbers are worked out by the same engine as the calculator above.
| Vial | For a 10 unit draw | For a 20 unit draw |
|---|---|---|
| 5 mg | Add 2 mL, get 10 units | Add 4 mL, get 20 units |
| 10 mg | Add 4 mL, get 10 units | Add 8 mL, get 20 units |
Water amounts for a 2.5 mg dose
The same idea for mg-sized doses, which come in bigger vials.
| Vial | For a 25 unit draw | For a 50 unit draw |
|---|---|---|
| 10 mg | Add 1 mL, get 25 units | Add 2 mL, get 50 units |
| 30 mg | Add 3 mL, get 25 units | Add 6 mL, get 50 units |
Notice the pattern: bigger vials need more water for the same draw, because the water has to spread across more doses. And every amount here is rounded to the nearest 0.1 mL, the smallest amount anyone can measure honestly, with the units recalculated from the rounded amount. So the units in the table are the units you will actually get.
BAC water, sterile water and saline are three different liquids
| Liquid | What it is | Preservative | Packaging |
|---|---|---|---|
| Bacteriostatic water | Sterile water with 0.9% benzyl alcohol | Yes, benzyl alcohol | Multi-dose vials |
| Sterile water for injection | Water sterilised for injection, nothing added | None | Single-use containers |
| Normal saline | 0.9% sodium chloride (salt) in water | None in single-dose forms | Vials and bags, mostly clinical use |
The preservative line is the one that matters in practice. A vial that gets punctured again and again needs something holding back bacterial growth between uses. That is the entire reason BAC water exists. Sources for the table are on the Methodology page.
Got the water amount? Here is the mixing itself
Clean the tops, draw the water, run it slowly down the inside wall of the vial, swirl, never shake. The full walkthrough, including what to do when it foams or will not dissolve, is in how to reconstitute peptides.
Common questions
How much BAC water do I add to a 10 mg vial?
It depends on your dose and the draw you want, so there is no single answer anyone can give you honestly. For a 250 mcg dose drawn as 10 units, a 10 mg vial needs 4.0 mL. For a 2.5 mg dose drawn as 50 units, it needs 2.0 mL. Put your own numbers into the calculator and it solves for the water directly.
Does adding more water weaken the peptide?
No. The amount in the vial is whatever the label says, and water does not change it. More water just spreads it thinner, so you draw more liquid to get the same dose. Less water makes a stronger mix and a smaller draw. Nothing is gained or lost either way. Only the draw size moves.
What draw size should I aim for?
Aim for one you can read. Draws under 5 units sit between the tiny marks on the barrel and are easy to get wrong. Draws over 100 units do not fit in a standard syringe at all. Somewhere in the middle is the practical zone, and the exact spot is your call. The calculator flags both problems when they come up.
Can I use sterile water instead of BAC water?
They are not the same product. Bacteriostatic water has 0.9% benzyl alcohol in it, which holds back bacterial growth, and it comes in vials meant to be entered more than once. Sterile water for injection has no preservative and is packaged for a single use. The comparison table below covers the practical differences, and the sources are on the Methodology page.
My draw comes out over 100 units. What does that mean?
It means your dose, in that mix, is more than 1 mL of liquid, and a U-100 syringe only holds 1 mL. The maths is fine. The mix is just too weak for a dose that size. Less water makes each unit stronger, so the same dose becomes a draw that fits.
How long does a reconstituted vial last?
The rule most people work to comes from the US Pharmacopeia: a multi-dose vial is dated 28 days from the first time it is punctured, unless the manufacturer gives a different period. The vial also needs proper storage in the fridge. The sources behind the rule are listed on the Methodology page, and the guide covers storage in more detail.
Arithmetic only
This calculator does maths on the numbers you enter. It works out concentration, draw volume and syringe units from the vial amount and water volume you give it. Nothing more.
It does not recommend amounts, schedules or products, and it does not know what is in your vial. It uses the amount printed on the label. If the label and the actual contents differ, the result differs too. For medical questions, talk to a clinician.
How the maths works, and where the facts on this site come from: Methodology and sources.