How much bacteriostatic water to add
Want the numbers for your own vial? Use the calculator. It works offline and nothing leaves your device.
What the water changes
Adding water doesn’t change how much is in the vial. It only changes how concentrated the mix is, and so how big each draw is.
- Less water: stronger mix. Each unit holds more, so draws are smaller.
- More water: weaker mix. Each unit holds less, so draws are bigger and easier to read.
The ~3 mL limit
Most vials only hold about 3 mL of water, so MixVials never suggests more than 3 mL. NAD+ is the exception: it usually comes in a larger vial, so MixVials allows up to 10 mL for NAD+.
Example (a 5 mg vial)
| Water | Concentration | Each unit |
|---|---|---|
| 1 mL | 5 mg/mL | 50 mcg |
| 2 mL | 2.5 mg/mL | 25 mcg |
| 3 mL | 1.67 mg/mL | 16.7 mcg |
This is a math example only, not a suggestion for any product.
Picking an amount
A good water amount puts the amount you need on an easy-to-read line, not under about 2 units, and not more than your syringe holds. The formula is:
water (mL) = amount in vial (mcg) × (units you want ÷ 100) ÷ amount per draw (mcg)
For example, a 5 mg (5,000 mcg) vial where you want 250 mcg to be 10 units: 5,000 × 0.10 ÷ 250 = 2 mL. If the answer is above 3 mL, use 3 mL and accept a slightly smaller draw. The calculator’s “Help me pick the water amount” does this for you.
Adding it
Add the water slowly down the inside wall of the vial, not straight onto the powder, then swirl or roll gently. Don’t shake. The video and steps on the homepage guide show how.