Peptide Reconstitution Calculator: BAC Water Reference Tables
Peptide dosing happens at the microgram scale. A 2mg vial reconstituted with 1mL of bacteriostatic water versus 2mL gives you a concentration that is exactly twice as strong, which means a 10-unit draw on an insulin syringe produces a dose of 200 mcg in one case and 100 mcg in the other. Getting this wrong by a factor of two is easy and consequential.
This page is a quick-reference resource: the formula, a lookup table for every common vial size and BAC water volume, and worked examples for the peptides researchers use most. If you want the step-by-step process for the physical reconstitution, that is covered in the full reconstitution guide. This page is the math.
The Formula
Concentration (mcg/mL) = Peptide amount (mcg) / BAC water added (mL)
Where peptide amount is the vial's labeled amount converted to micrograms: 1mg = 1000 mcg, 5mg = 5000 mcg, 10mg = 10000 mcg
Once you know your concentration, the dose for any draw volume is:
Dose (mcg) = Volume drawn (mL) x Concentration (mcg/mL)
On a U-100 insulin syringe: 1 unit = 0.01mL. So 10 units = 0.1mL, 20 units = 0.2mL, etc.
That is the complete math. The tables below apply it for every common vial size so you do not have to calculate by hand each time.
Master Reference Table
Each cell shows: concentration in mcg/mL and the dose delivered by drawing 10 units (0.1mL) on a standard U-100 insulin syringe.
| Vial size | 0.5mL BAC water | 1mL BAC water | 2mL BAC water | 3mL BAC water | 5mL BAC water |
|---|---|---|---|---|---|
| 1mg (1000 mcg) | 2000 mcg/mL 10u = 200 mcg |
1000 mcg/mL 10u = 100 mcg |
500 mcg/mL 10u = 50 mcg |
333 mcg/mL 10u = 33 mcg |
200 mcg/mL 10u = 20 mcg |
| 2mg (2000 mcg) | 4000 mcg/mL 10u = 400 mcg |
2000 mcg/mL 10u = 200 mcg |
1000 mcg/mL 10u = 100 mcg |
667 mcg/mL 10u = 67 mcg |
400 mcg/mL 10u = 40 mcg |
| 5mg (5000 mcg) | 10000 mcg/mL 10u = 1000 mcg |
5000 mcg/mL 10u = 500 mcg |
2500 mcg/mL 10u = 250 mcg |
1667 mcg/mL 10u = 167 mcg |
1000 mcg/mL 10u = 100 mcg |
| 10mg (10000 mcg) | 20000 mcg/mL 10u = 2000 mcg |
10000 mcg/mL 10u = 1000 mcg |
5000 mcg/mL 10u = 500 mcg |
3333 mcg/mL 10u = 333 mcg |
2000 mcg/mL 10u = 200 mcg |
| 20mg (20000 mcg) | 40000 mcg/mL 10u = 4000 mcg |
20000 mcg/mL 10u = 2000 mcg |
10000 mcg/mL 10u = 1000 mcg |
6667 mcg/mL 10u = 667 mcg |
4000 mcg/mL 10u = 400 mcg |
Dose Lookup: Target Dose to Injection Volume
If you already know your concentration and want to find the injection volume for a specific target dose, use this table. Volumes shown in both mL and U-100 syringe units.
| Target dose | 500 mcg/mL | 1000 mcg/mL | 2000 mcg/mL | 2500 mcg/mL | 5000 mcg/mL |
|---|---|---|---|---|---|
| 50 mcg | 0.1mL / 10u | 0.05mL / 5u | 0.025mL / 2.5u | 0.02mL / 2u | 0.01mL / 1u |
| 100 mcg | 0.2mL / 20u | 0.1mL / 10u | 0.05mL / 5u | 0.04mL / 4u | 0.02mL / 2u |
| 200 mcg | 0.4mL / 40u | 0.2mL / 20u | 0.1mL / 10u | 0.08mL / 8u | 0.04mL / 4u |
| 250 mcg | 0.5mL / 50u | 0.25mL / 25u | 0.125mL / 12.5u | 0.1mL / 10u | 0.05mL / 5u |
| 500 mcg | 1mL / 100u | 0.5mL / 50u | 0.25mL / 25u | 0.2mL / 20u | 0.1mL / 10u |
| 1000 mcg | 2mL / 200u | 1mL / 100u | 0.5mL / 50u | 0.4mL / 40u | 0.2mL / 20u |
U-100 Syringe Unit Reference
All the doses above assume you are using a standard U-100 insulin syringe, which is the default for subcutaneous peptide injections. U-100 means 100 units = 1mL. The math:
| Syringe units | Volume in mL | Volume in mcL (microliters) |
|---|---|---|
| 1 unit | 0.01 mL | 10 mcL |
| 5 units | 0.05 mL | 50 mcL |
| 10 units | 0.1 mL | 100 mcL |
| 20 units | 0.2 mL | 200 mcL |
| 25 units | 0.25 mL | 250 mcL |
| 50 units | 0.5 mL | 500 mcL |
| 100 units | 1.0 mL | 1000 mcL |
If you are using a U-40 syringe (less common, used for some insulin types), the conversion is different: 1 unit = 0.025mL. Do not mix up U-100 and U-40 syringes, as the error is a 2.5x overdose in the wrong direction.
Worked Examples for Common Peptides
BPC-157: 250 mcg daily dose
Setup
Vial: 5mg (5000 mcg) BPC-157
BAC water added: 2mL
Concentration: 5000 / 2 = 2500 mcg/mL
Target dose: 250 mcg
Injection volume: 250 / 2500 = 0.1mL = 10 units on U-100 syringe
Doses per vial: 5000 / 250 = 20 doses
CJC-1295 (no DAC): 100 mcg per injection
Setup
Vial: 5mg (5000 mcg) CJC-1295 without DAC
BAC water added: 2mL
Concentration: 5000 / 2 = 2500 mcg/mL
Target dose: 100 mcg
Injection volume: 100 / 2500 = 0.04mL = 4 units on U-100 syringe
Doses per vial: 5000 / 100 = 50 doses
Ipamorelin: 200 mcg per injection
Setup
Vial: 5mg (5000 mcg) ipamorelin
BAC water added: 2mL
Concentration: 5000 / 2 = 2500 mcg/mL
Target dose: 200 mcg
Injection volume: 200 / 2500 = 0.08mL = 8 units on U-100 syringe
Doses per vial: 5000 / 200 = 25 doses
Note: if combining CJC-1295 and ipamorelin in the same syringe at the above concentrations, draw 4 units of CJC + 8 units of ipamorelin = 12 units total in one syringe delivering 100 mcg + 200 mcg.
Sermorelin: 300 mcg bedtime dose
Setup
Vial: 9mg (9000 mcg) sermorelin (common vial size)
BAC water added: 3mL
Concentration: 9000 / 3 = 3000 mcg/mL
Target dose: 300 mcg
Injection volume: 300 / 3000 = 0.1mL = 10 units on U-100 syringe
Doses per vial: 9000 / 300 = 30 doses
Semaglutide: 0.25mg (250 mcg) starter dose
Setup
Vial: 5mg (5000 mcg) semaglutide
BAC water added: 2mL
Concentration: 5000 / 2 = 2500 mcg/mL
Target dose: 250 mcg (0.25mg)
Injection volume: 250 / 2500 = 0.1mL = 10 units on U-100 syringe
Doses per vial: 5000 / 250 = 20 doses (weekly dosing, approximately 5 months)
Choosing How Much BAC Water to Add
There is no single correct answer, but a few principles help.
Aim for a manageable injection volume. Most researchers prefer injecting between 0.1mL and 0.3mL subcutaneously. Volumes below 0.05mL are hard to measure accurately on a standard syringe and hard to inject completely. Volumes above 0.5mL can be uncomfortable subcutaneously and may cause temporary pooling under the skin.
Work backward from your target dose. If your dose is 100 mcg and you want to inject roughly 0.1mL (10 units), you need a concentration of 1000 mcg/mL. For a 5mg vial, that means adding 5mL of BAC water. If you prefer a 0.04mL injection instead, you need 2500 mcg/mL, meaning 2mL of BAC water. Both are correct, but the 2mL choice is more common because it yields a higher concentration that remains comfortable to inject in small volumes.
Consider the number of doses per vial. More BAC water per vial lowers concentration but means a larger total solution volume. A 5mg vial reconstituted with 5mL gives 1000 mcg/mL: fine for 100mcg doses (50 doses per vial) but requires 1mL injections for 1000mcg doses. Match your reconstitution volume to the doses you actually plan to draw.
Medical disclaimer. This page is a mathematical reference for educational purposes only. It does not constitute medical advice. The peptides referenced are research compounds not approved for human use. Nothing here is a recommendation to use any peptide. Consult a qualified clinician before handling any research compound.
Common Reconstitution Mistakes
Adding water too fast. Squirting BAC water directly onto the lyophilized powder from above can damage fragile peptide structure. Aim the stream at the inside wall of the vial and let it run down slowly. Swirl, do not shake. See the reconstitution guide for full technique.
Forgetting to note the concentration. Write the concentration and reconstitution date on the vial with a marker or label before you put it in the fridge. You will not remember it in three days. A vial with unknown concentration is effectively unusable for accurate research.
Using plain sterile water instead of bacteriostatic water. Sterile water has no preservative. It is for single-dose use only. Using it across multiple draws from the same vial introduces contamination risk over time. BAC water with 0.9% benzyl alcohol is the correct choice for multi-draw peptide vials.
Freezing a reconstituted vial. Lyophilized (freeze-dried) peptide survives freezing and should be stored frozen until use. A vial that has already been reconstituted into solution should not be re-frozen. Freeze-thaw cycling causes protein aggregation and potency loss. Store reconstituted peptides in the refrigerator (2 to 8 degrees Celsius) and use them within the window stated on the certificate of analysis, typically up to 28 days.
Mixing vial sizes. A 5mg vial and a 5000 IU vial (the latter used for some hormones like HCG) are measured in different units and are not interchangeable in these calculations. Peptide vials sold for research are almost always labeled in milligrams or micrograms, not international units.
Key Takeaways
- Concentration (mcg/mL) = total peptide in mcg / BAC water added in mL.
- Dose = volume drawn in mL x concentration in mcg/mL.
- On a U-100 insulin syringe, 10 units = 0.1mL. Use that as your anchor unit.
- A 5mg vial with 2mL BAC water gives 2500 mcg/mL: 10 units = 250 mcg. This is the most common setup for GH peptides at 100 to 200 mcg doses.
- Aim for an injection volume of 0.05 to 0.3mL for comfortable subcutaneous delivery.
- Label your vial with the concentration and reconstitution date immediately after reconstituting.
- Use bacteriostatic water for multi-draw vials; do not freeze reconstituted solution.
Frequently Asked Questions
How much BAC water do I add to a 5mg peptide vial?
For a 5mg (5000 mcg) vial, adding 1mL gives 5000 mcg/mL (10 units on a U-100 syringe = 500 mcg) and adding 2mL gives 2500 mcg/mL (10 units = 250 mcg). The right amount depends on your target dose and what injection volume feels comfortable. 2mL is the most common choice for 5mg vials used in GH peptide research at 100 to 200 mcg doses.
How do I calculate peptide dose from syringe units?
On a U-100 syringe, 1 unit = 0.01mL. Multiply units drawn by 0.01 to get mL, then multiply by your concentration in mcg/mL. Example: 10 units at 2500 mcg/mL = 0.1mL x 2500 = 250 mcg. The tables on this page do that math for you for every common combination.
What is bacteriostatic water and why is it used?
Bacteriostatic water contains 0.9% benzyl alcohol as a preservative. This inhibits bacterial growth, making the reconstituted solution safe for multi-draw use over up to 28 days when refrigerated. Standard sterile water has no preservative and is for single injections only. Always use BAC water when you plan to draw from the same vial more than once.
What syringe should I use for peptide injections?
A U-100 insulin syringe is standard. These come in 0.3mL (30 unit), 0.5mL (50 unit), and 1mL (100 unit) sizes. For low microgram doses, the smaller 0.3mL syringe gives better precision because the scale markings are closer together. A 28 to 31 gauge, half-inch needle is the standard for subcutaneous abdominal injection.
How long does a reconstituted peptide last?
Reconstituted with bacteriostatic water and stored at 2 to 8 degrees Celsius, most peptides are considered stable for up to 28 days. Check the vendor's certificate of analysis for the specific window, as some peptides are more labile than others. Do not refreeze a reconstituted vial. Lyophilized (dry) peptide should be stored frozen until you are ready to reconstitute.