Most reconstitution calculators divide once and hand you a number like 23.7 units, which nobody can accurately measure on an insulin syringe. This one treats the water volume as what it actually is, a variable you get to choose, and solves backwards for the mixing that puts your dose on a clean mark.
Educational tool only, not medical advice. Verify every dose independently and use sterile technique. Reconstituted peptide stability and shelf life vary by compound and storage.
Concentration is the amount of peptide divided by the water you add. The volume you inject is your dose divided by that concentration, and units on a U-100 syringe are simply that volume multiplied by one hundred.
Run forwards, an arbitrary water volume gives an awkward decimal. Run backwards, you can pick the water volume that makes the answer land on ten units, or twenty, or fifty, which you can actually measure. The tool sweeps every practical mixing volume and ranks them. The hCG Dosage Calculator uses the same backwards-solving approach for IU-dosed compounds specifically, and the Injection Dose Calculator converts any milligram dose into an exact draw once you know your concentration.
A one millilitre U-100 syringe is marked every two units. A half millilitre syringe is marked every one. That means the same ten unit draw is twice as precise on the smaller barrel, and the tool tells you when switching syringes would meaningfully improve your accuracy.
It also reports the dosing error a half mark misread would cause, which is how you find out that a very small draw on a large syringe is far less accurate than it looks.
Two vials of the same milligram strength do not require the same units, because the doses are different. Drawing the same amount from a BPC-157 vial and a TB-500 vial, which is easy to do when both say five milligrams, can underdose the TB-500 by roughly eightfold. The calculator solves each vial separately and flags the gap when it is large. Check dose ranges for both compounds, and dozens more, in The Peptide Database, or build a full injury protocol in the BPC-157 & TB-500 Protocol Builder.
There is no single correct amount, because the water only sets the concentration. Choose the volume that makes your intended dose land on an easily readable syringe mark, usually somewhere between one and three millilitres for a typical vial. This calculator finds that volume for you.
Multiply your dose by the water volume in millilitres, then divide by the vial amount in micrograms, then multiply by one hundred for a U-100 syringe. The calculator does this and also checks whether the result is precisely measurable.
U-100 syringes have one hundred units per millilitre and are standard in the US, UK and Europe. U-40 syringes have forty units per millilitre and are common in India and in veterinary use. Using the wrong one produces a dose that is off by a factor of two and a half.
Bacteriostatic water for anything you will draw from more than once, because it contains a preservative that inhibits bacterial growth. Sterile water has no preservative and is only appropriate for single use.
Add the water slowly down the inside wall of the vial rather than directly onto the powder, then swirl gently until dissolved. Never shake. Refrigerate after reconstitution.
