How Much Bacteriostatic Water for an HCG 5000 IU Vial?
A 5000 IU vial of HCG reconstituted with 2 mL of bacteriostatic water gives a concentration of 2500 IU/mL; with 1 mL it gives 5000 IU/mL. The calculation depends only on the quantity in the vial and the volume of water added, so the figures below apply to any 5000 IU vial.
View product →There is no single correct volume. Adding more water does not change how much is in the vial. It spreads the same quantity through a larger volume, which changes how many syringe units correspond to a given amount. The tables on this page use volumes that produce round numbers on a U-100 syringe; other volumes work identically as long as the resulting concentration is written on the vial.
Concentration by water volume
Concentration is the quantity in the vial divided by the water volume. A 5000 IU vial holds 5000 IU whether it receives 1 mL or 5 mL; only the IU/mL figure moves. The right-hand column converts each concentration into the number of U-100 units that contain 500 IU.
| Vial | Bacteriostatic water added | Concentration | Units containing 500 IU |
|---|---|---|---|
| 5000 IU HCG | 1 mL | 5000 IU/mL | 10 units |
| 5000 IU | 2 mL | 2500 IU/mL | 20 units |
| 5000 IU | 5 mL | 1000 IU/mL | 50 units |
Before choosing a larger volume, check that the vial has headspace for it. A 10 mL vial of bacteriostatic water reconstitutes five 5000 IU vials at 2 mL each.
Reading the concentration on a U-100 syringe
A U-100 insulin syringe is graduated in units, and 100 units equal 1 mL. Units are therefore millilitres multiplied by 100: 0.1 mL is 10 units and 0.25 mL is 25 units. A 0.5 mL syringe carries 50 units and a 0.3 mL syringe carries 30 units on the same scale, with finer markings that make small volumes easier to read.
To find the volume that contains a given amount, divide the amount by the concentration. At 2500 IU/mL (a 5000 IU vial with 2 mL of water), the volume that contains 500 IU is 500 divided by 2500, which is 0.2 mL, or 20 units. The table below runs the same calculation for four arbitrary amounts. They illustrate the arithmetic and nothing else.
| Amount (illustrative) | Volume at 2500 IU/mL | U-100 units |
|---|---|---|
| 250 IU | 0.1 mL | 10 units |
| 500 IU | 0.2 mL | 20 units |
| 1000 IU | 0.4 mL | 40 units |
| 1500 IU | 0.6 mL | 60 units |
At 5000 IU/mL, which the same vial gives with 1 mL of water, every volume in the table moves in proportion: a 1000 IU draw measures 20 units instead of 40. Volumes below about 0.1 mL are hard to read accurately on a 1 mL syringe. Either move to a 0.3 mL or 0.5 mL syringe, or reconstitute with more water so that the same mass occupies a larger, more legible volume.
HCG is supplied by Vistara Labs as a lyophilised material for research use. The quantities on this page illustrate the arithmetic of dilution and measurement only.
The HCG vial
HCG (human chorionic gonadotropin) is a glycoprotein hormone, labelled in international units rather than milligrams because its biological activity, not its mass, is what is standardised. The arithmetic is identical with IU in place of mg: 5000 IU in 2 mL is 2500 IU/mL, and 10 units on a U-100 syringe hold 250 IU. Vistara Labs supplies it as a 5000 IU lyophilised vial.
HCG is a large glycoprotein, around 37 kDa, built from two subunits. The alpha subunit is shared with LH, FSH and TSH; the beta subunit is what makes it HCG. Sugar chains make up a large share of its mass, and they vary from batch to batch, which is why HCG is standardised by biological activity in international units rather than by weight. Its clinical history in fertility medicine is covered in HCG: what it is and why it is measured in IU.
Reconstitution technique
Let the vial reach room temperature, swab both stoppers, and run the measured water slowly down the inside wall of the vial rather than onto the powder. Swirl or tilt gently until the cake dissolves, never shake, and give any remaining powder a few minutes to settle into solution. Label the vial with the date and the concentration, then keep it refrigerated at 2 to 8 °C and protected from light. The full method, with the reason behind each step, is in how to reconstitute peptides with bacteriostatic water.
Why the solution should look clear
Properly reconstituted HCG forms a clear, colourless solution. Cloudiness, strands or a gel that will not disperse usually mean the water went in too fast or the vial was shaken; haze that appears later points to warm or bright storage. The causes are covered in why peptides gel or go cloudy.
Bacteriostatic water, not sterile water
Bacteriostatic water is sterile water with 0.9% benzyl alcohol, a preservative that allows a refrigerated vial to be accessed more than once; plain sterile water is intended for single access. The difference is explained in bacteriostatic water explained.
Frequently asked questions
How much bacteriostatic water do I add to a 5000 IU vial of HCG?
There is no single correct volume. With 2 mL of bacteriostatic water a 5000 IU vial of HCG gives 2500 IU/mL; with 1 mL it gives 5000 IU/mL. Adding more water does not change the quantity in the vial, it spreads it through a larger volume, so write the concentration you chose on the vial.
How many 5000 IU vials does a 10 mL vial of bacteriostatic water cover?
A 10 mL vial of bacteriostatic water reconstitutes five 5000 IU vials at 2 mL each. Check that the peptide vial has headspace for the volume before choosing a larger one.
How many units on a U-100 syringe contain 500 IU at 2500 IU/mL?
At 2500 IU/mL (a 5000 IU vial with 2 mL of water), the volume that contains 500 IU is 500 divided by 2500, which is 0.2 mL, or 20 units. Units are millilitres multiplied by 100, so 0.1 mL is 10 units. The amounts on this page illustrate the arithmetic only.
What should reconstituted HCG look like?
Properly reconstituted HCG forms a clear, colourless solution. Cloudiness, strands or a gel that will not disperse usually mean the water went in too fast or the vial was shaken; haze that appears later points to warm or bright storage. More on the causes in why peptides gel or go cloudy.
Can I use sterile water instead of bacteriostatic water?
Only for a vial that will be accessed once. Bacteriostatic water is sterile water with 0.9% benzyl alcohol, a preservative that allows a refrigerated vial to be accessed more than once; plain sterile water is intended for single access. Details in bacteriostatic water explained.
How should a reconstituted HCG vial be stored?
Refrigerated at 2 to 8 °C, protected from light and labelled with the date and the concentration. Unopened lyophilised vials are kept cold and dark until they are needed. The full storage guide is how to store research peptides.
Work it out for a different vial or concentration
Our peptide calculator works in milligrams and micrograms; for an IU-labelled vial, use the IU figure in place of the mass and the same division applies: amount wanted divided by concentration gives millilitres, and millilitres multiplied by 100 gives U-100 units.
Products: HCG 5000 IU and bacteriostatic water 10 mL.
References
hCG has an extensive controlled human research literature; it is a glycoprotein hormone rather than a short research peptide.
- Low-dose human chorionic gonadotropin maintains intratesticular testosterone in normal men with testosterone-induced gonadotropin suppressionRandomised trial; 29 normal men on testosterone enanthate randomised to placebo or varying hCG doses.
- A double-blind, placebo-controlled, randomized clinical trial of recombinant human chorionic gonadotropin on muscle strength and physical function and activity in older men with partial age-related androgen deficiencyDouble-blind, placebo-controlled randomised trial in older men with partial age-related androgen deficiency.
Links open the study record on PubMed so the source can be checked directly. Listing a study is not a claim that its findings apply to any other use, product or route of administration. Research use only.
