Peptide Calculator
Calculate exact reconstitution volumes, syringe units and applications per vial for any peptide.
Almost all insulin syringes are U-100. Choose U-40 only if the syringe says so.
This tool is for educational and informational purposes only. It performs reconstitution calculations and is in no case a prescription, medical advice, a diagnosis or instructions to follow. Only a healthcare professional can recommend or prescribe a treatment. The products are sold exclusively for research.
—
If the amount is going to increase in stages, here you can see how many units you will need to draw at each stage. All values in milligrams. Enter your preparation (vial and water) and we will tell you the units for each stage.
| Stage | Amount | Dates | Draw |
|---|
Tap any stage to see it on the syringe.
—
You define the step-up. This tab only does the arithmetic: it does not suggest amounts or schedules.
Get your protocol
We only use your data to send you the protocol and, if you check the box, our news. We never share it with third parties.
Select a peptide
How to reconstitute a vial, step by step
Order matters. These five steps separate an intact solution from a degraded peptide before the first draw.
- 1Let both vials reach room temperature
Remove the lyophilized peptide from the refrigerator and wait. Adding cold water to cold powder makes it more likely that undissolved material stays stuck to the vial wall.
- 2Disinfect both septa
Isopropyl alcohol on the rubber stopper of the peptide and on that of the bacteriostatic water. Let them air dry: do not blow on them or wipe them with paper.
- 3Add the water down the wall, slowly
Draw the volume the calculator gives you and inject it angling the needle against the inner wall of the vial. A direct stream onto the powder breaks peptide chains.
- 4Mix the product and wait
Roll the vial between your fingers slowly and gently and let it rest. Fully dissolving may require several minutes. Do not shake it vigorously: strong shaking creates foam and denatures the peptide.
- 5Label and refrigerate
Write the peptide, the resulting concentration and the date on the vial itself. Three weeks from now you will not remember. Store it between 2 and 8 °C, upright and protected from light.
Why the calculation is the critical point
All the precision of a protocol is decided at one specific moment: when you choose how much bacteriostatic water goes into the vial. That number, and only that number, sets the concentration of the solution and, with it, every amount you will draw over the following weeks.
The costly mistake is not being far off; it is being slightly off without noticing. If you add 4 ml where 2 were needed, the concentration drops by half and each draw contains half of what was intended. The protocol seems not to work, it drags on, the amount gets raised by guesswork. And the cause was a calculation made before starting.
The underlying difficulty is that there are four chained unit systems and each jump is a chance to make a mistake:
- The vial is sold in milligrams.
- The amounts for most peptides are expressed in micrograms.
- The volume to draw is measured in milliliters.
- And the insulin syringe, which is the actual tool, is graduated in units.
The calculator solves the whole chain at once and in one place, with no intermediate conversions by hand: which is exactly where extra zeros creep in.
What you enter and what you get
What you enter
- Vial milligrams
- The total content of lyophilized peptide, as shown on the label. If you are reusing a partly used vial, enter only what is left.
- Bacteriostatic water
- The volume you are going to add. It is the only value that determines the concentration: 10 mg in 2 ml gives 5 mg/ml; the same 10 mg in 5 ml gives 2 mg/ml.
- Target amount
- The amount for each application. You can enter it in micrograms or milligrams with the toggle.
- Syringe and calibration
- Capacity (0.3 / 0.5 / 1 ml) and scale. They determine which mark to pull the plunger to and whether the volume fits.
What you get
- Units to draw
- The number you actually use with the syringe in hand: the exact mark to pull to.
- Concentration
- The mg/ml of the reconstituted solution. Write it on the vial: it lets you recalculate anything later.
- Volume per application
- The exact milliliters of each draw.
- Applications per vial
- How many applications the vial yields, so you know when to restock before you run short.
Bacteriostatic water: why not just any water
Bacteriostatic water is sterile water with 0.9% benzyl alcohol. That preservative inhibits the growth of bacteria and fungi, and it is what allows the same vial to be punctured many times over several weeks.
Every time you pierce the septum with a needle you introduce a small risk of contamination. With plain sterile water, without preservative, that risk builds up draw after draw. That is why sterile water only makes sense when the whole vial is used in a single session; for a protocol of twenty or thirty applications, the right choice is bacteriostatic water.
Which syringe to choose
The three common insulin syringe sizes cover practically any scenario. The difference is not in the precision of the scale — on all three, one unit is 0.01 ml — but in the capacity and how easy it is to read.
For small volumes, below 0.2 ml. The easiest to read accurately because the marks are spaced farther apart.
The most versatile, and the one we recommend if you are only going to have one. It covers most protocols without falling short.
Needed when the volume exceeds 0.5 ml or when combining several peptides. It requires good light to read small volumes.
Storage before and after reconstitution
Lyophilized, unopened
Lyophilized powder is considerably more stable than people tend to think: lyophilization removes moisture, the main driver of degradation. In the refrigerator (2–8 °C) it lasts for months. For long-term storage, −20 °C.
The rule you cannot skip: avoid freeze-thaw cycles. Each cycle damages the molecular structure. If you freeze a vial, plan to use all of it once thawed.
Already reconstituted
As soon as the water goes in, the countdown starts. The solution goes in the refrigerator (2–8 °C, never in the freezer) and is used within the window specific to that peptide, usually 21 to 30 days.
Do not freeze a reconstituted solution. Ice crystals physically alter the structure of the peptide and cause aggregation. If in doubt between two time frames, go with the shorter one.
What to do with used needles
Used needles are sharps waste and cannot go in household trash: a needlestick through a bag is a real risk for whoever handles that waste later. They go in a rigid sharps container, which you can buy at a pharmacy and hand in when full at the collection point designated by your local authority or at the pharmacy itself.
Never recap a used needle or try to separate it from the barrel: most accidental needlesticks happen during exactly that motion. Syringe and needle go into the container whole. Empty vials with no residue can go into glass or plastic recycling as appropriate.
Vial sizes in our catalog
The available formats and the volume of water we usually work with for each one. Each row loads that peptide into the calculator.
| Peptide | Category | Vials | Suggested water | Concentration |
|---|
The suggested water is only a starting point to bring the concentration to a manageable value. Use whatever volume you prefer: the calculator adjusts.
Frequently asked questions
What is the difference between mg and mcg?
One milligram is 1,000 micrograms. Vials are labeled in mg and many amounts are expressed in mcg, so the unit jump comes up constantly. A factor-of-1,000 error at that point is the most common and the most serious mistake. The mcg/mg toggle exists precisely so you do not have to do that conversion in your head.
How much bacteriostatic water should I add?
There is no single answer: the volume only determines the concentration. As a practical rule, choose the volume that puts the amount you are calculating in a comfortable range on the syringe, between 10 and 40 units. Below 5 IU the relative reading error shoots up; above the syringe capacity you would have to inject twice.
What does U-100 mean?
It means that 100 units on the scale equal 1 ml, that is, 1 IU = 0.01 ml. It is the standard for almost all insulin syringes. U-40 syringes (1 IU = 0.025 ml) are uncommon and used mainly in veterinary medicine. If your syringe does not have U-40 printed on it, it is U-100.
My calculated volume is tiny. What should I do?
It means the solution is too concentrated for that amount. The fix is to reconstitute with more water: the same vial in twice the volume puts the same amount in twice as many units, which is much easier to measure. If the vial is already reconstituted, do not dilute it: use a 0.3 ml syringe, which has more widely spaced marks.
Can I draw two peptides into the same syringe?
Physically, yes, and it is common with well-documented combinations. But each peptide has its own stability and optimal pH, and mixing them in the barrel can speed up the degradation of one of the two. If you combine them, do it right before the application and never mix them inside a vial for storage.
Do I have to recalculate for each application?
No. As long as you do not change the vial or the amount, the number of units stays the same. Calculate once when you reconstitute, write the concentration and units on the vial itself, and from then on just read the label. Recalculate when you open a new vial or change the amount.
The solution looks cloudy. Can I use it?
No. Cloudiness, a change in color or suspended particles indicate contamination or degradation. Discard the vial. If it appears right after reconstitution, it is usually caused by shaking or by a stream of water hitting the powder too hard.
Do the calculations work for any peptide?
Yes: the reconstitution math is identical for all of them. What changes between peptides is the amount, the frequency and the stability in solution, not the formula. That is why the selector only preloads starting values; the calculation itself is universal.
Everything you need to reconstitute
Peptides with a certificate of analysis per batch and bacteriostatic water.