Tools / 20 mg vial
20 mg vial: how much water and how many units
How strong a 20 mg vial is after mixing, how many units each dose is on a U-100 syringe, and how many doses it holds. Pick your water amount and read across.
With 2 mL: 20 mg + 2 mL water = 10 mg/mL. Each unit holds 100 mcg, so 1 mg is the 10-unit line.
The mg printed on the vial label.
Bacteriostatic (bac) water, in mL.
Check whether it says mcg or mg. They differ by 1,000 times.
It's printed on the packet: 0.3, 0.5 or 1 mL.
20 mg vial + 2 mL water → 1 mg dose
Fill your syringe to
10units
The 10 line on a 1 mL syringe, which is 0.1 mL.
- Strength after mixing
- 10 mg/mL
- Each unit holds
- 100 mcg
- Doses in this vial
- 20
Show the math
- 20 mg × 1,000 = 20,000 mcg in the vial
- 20,000 mcg ÷ 2 mL = 10,000 mcg/mL
- 1,000 mcg ÷ 10,000 mcg/mL = 0.1 mL
- 0.1 mL × 100 units/mL = 10 units
Not what you expected? Check the numbers above, and confirm with your prescriber or pharmacist before you inject.
Checked November 8, 2026 by the PeptideTracker editorial team · This tool does the math only. It doesn't recommend a dose.
[02] Strength
How strong is a 20 mg vial after mixing?
A 20 mg vial mixed with 2 mL of bac water is 10 mg/mL, so each unit on a U-100 insulin syringe (0.01 mL) holds 100 mcg. More water makes each unit weaker.
| Water added | Strength | Each unit holds |
|---|---|---|
| 1 mL | 20 mg/mL | 200 mcg |
| 2 mL | 10 mg/mL | 100 mcg |
| 3 mL | 6.667 mg/mL | 66.67 mcg |
| 5 mL | 4 mg/mL | 40 mcg |
[03] Units
How many units is each dose from a 20 mg vial?
With 2 mL of water, 1 mg is 10 units on a U-100 syringe. The table shows example doses across water amounts. These are examples for the math, not recommended doses.
| Dose | 1 mL water | 2 mL water | 3 mL water | 5 mL water |
|---|---|---|---|---|
| 500 mcg | 2.5 units | 5 units | 7.5 units | 12.5 units |
| 1 mg | 5 units | 10 units | 15 units | 25 units |
| 2.5 mg | 12.5 units | 25 units | 37.5 units | 62.5 units |
| 5 mg | 25 units | 50 units | 75 units | 125 (over 100) |
[04] Doses per vial
How many doses are in a 20 mg vial?
The water doesn't change this. A 20 mg vial holds 20,000 mcg in total, so the number of doses depends only on the dose size.
| Dose | Full doses | Left over |
|---|---|---|
| 500 mcg | 40 | none |
| 1 mg | 20 | none |
| 2.5 mg | 8 | none |
| 5 mg | 4 | none |
[05] Round lines
Water that puts 1 mg on a round line (20 mg vial)
To land 1 mg on a round line, add 2 mL: each dose is then the 10-unit line on a 1 mL syringe. Use the bac water planner to check your own dose, and read how much bac water to add for what changes with more or less water.
[06] Questions
Questions
How much bac water do I add to a 20 mg vial?
Any amount works for the math. 2 mL is common: it makes the vial 10 mg/mL, so each unit holds 100 mcg. More water spreads each dose over more units, which makes small doses easier to measure.
How many units is 1 mg from a 20 mg vial?
With 2 mL of water it's 10 units on a U-100 syringe. With 1 mL it's 5 units, and with 3 mL it's 15 units.
How many 1 mg doses are in a 20 mg vial?
20 full doses. The water you add doesn't change that.
Spotted a mistake or something out of date? Tell us. We aim to fix factual errors within two working days.
[07] Read next
Guides that go with this calculator
- How to reconstitute peptidesMixing (reconstituting) means adding bacteriostatic (bac) water to the freeze-dried powder in your vial so you can measure out doses. How much water you add, and how you add it, sets every dose that follows.
- How much bac water to add to a peptide vialThere's no single right amount. The water sets how much peptide each unit on your syringe holds, so choose an amount that puts your dose on a line you can read.
- How to read an insulin syringeThe numbers on the barrel are units of liquid, not milligrams of medicine. To read one correctly, check the scale, line up the top edge of the plunger with your number and clear any air.
- How long do reconstituted peptides last?Nobody has published tested numbers for research peptides once they're mixed. Approved peptides and GLP-1 pens do have exact label limits, and they vary a lot from product to product.
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