Peptide calculator: reconstitution, mL and syringe units
The free peptide calculator for reconstitution. From milligrams in the vial to concentration, millilitres and U-100 syringe units, worked out as you type, with a water finder, reference tables and a worked example. Pick a vial, set the diluent, enter the amount you want to measure.
- Concentrationvial mg ÷ diluent mL
- Volumetarget ÷ concentration
- Unitsvolume × 100 (U-100)
0.100 mL on a 1 mL U-100 syringe
Assumes complete dissolution and a U-100 scale (100 units = 1 mL). Round to what your syringe can measure. Laboratory arithmetic only, not guidance for any use of the solution.
Divide the milligrams in the vial by the millilitres of water to get the concentration. Divide the amount you want by the concentration to get the volume. Multiply the volume in mL by 100 for units on a U-100 insulin syringe.
How much bacteriostatic water to add
Work backwards: choose the syringe reading you want for a given amount, and the finder gives the diluent volume that produces it.
gives 5.00 mg/mL; 500 mcg reads as 10 units on a U-100 syringe.
Quick presets for the vials we stock
One click loads the vial size and a sensible diluent volume into the calculator above. Change any value afterwards.
Peptide reconstitution chart: syringe units by vial size
The units a given amount reads as on a U-100 syringe, for the common vial sizes and water volumes. Each cell also gives the volume in mL. A dash means the amount is more than the vial holds. This is arithmetic only; it doesn't suggest an amount for any use.
| Amount | 5 mg in 2 mL2.5 mg/mL | 10 mg in 2 mL5 mg/mL | 10 mg in 3 mL3.33 mg/mL | 40 mg in 2 mL20 mg/mL | 40 mg in 3 mL13.33 mg/mL | 50 mg in 3 mL16.67 mg/mL | 100 mg in 3 mL33.33 mg/mL |
|---|---|---|---|---|---|---|---|
| 100 mcg | 4 u0.04 mL | 2 u0.02 mL | 3 u0.03 mL | 0.5 utoo small to read | 0.75 utoo small to read | 0.6 utoo small to read | 0.3 utoo small to read |
| 250 mcg | 10 u0.1 mL | 5 u0.05 mL | 7.5 u0.075 mL | 1.25 utoo small to read | 1.88 utoo small to read | 1.5 utoo small to read | 0.75 utoo small to read |
| 500 mcg | 20 u0.2 mL | 10 u0.1 mL | 15 u0.15 mL | 2.5 u0.025 mL | 3.8 u0.0375 mL | 3 u0.03 mL | 1.5 utoo small to read |
| 1 mg | 40 u0.4 mL | 20 u0.2 mL | 30 u0.3 mL | 5 u0.05 mL | 7.5 u0.075 mL | 6 u0.06 mL | 3 u0.03 mL |
| 2 mg | 80 u0.8 mL | 40 u0.4 mL | 60 u0.6 mL | 10 u0.1 mL | 15 u0.15 mL | 12 u0.12 mL | 6 u0.06 mL |
| 2.5 mg | 100 u1 mL | 50 u0.5 mL | 75 u0.75 mL | 12.5 u0.125 mL | 18.8 u0.1875 mL | 15 u0.15 mL | 7.5 u0.075 mL |
| 5 mg | 200 u2 mL | 100 u1 mL | 150 u1.5 mL | 25 u0.25 mL | 37.5 u0.375 mL | 30 u0.3 mL | 15 u0.15 mL |
How to use the peptide calculator
- Vial. Pick a compound to load its vial size, or type the milligrams printed on any vial label.
- Diluent. Enter the millilitres of bacteriostatic water you added (or plan to add).
- Amount to measure. Enter the amount you want in each aliquot, in mcg or mg.
- Syringe. Choose 1 mL, 0.5 mL or 0.3 mL. All are U-100; the smaller barrels are easier to read at low volumes.
The readout shows the syringe units, the volume in mL, the concentration, how much each unit holds and how many aliquots the vial gives. A status chip warns when a reading is under 4 units (hard to measure accurately) or more than the syringe holds. Copy the result as text, or copy a link that reopens the calculator with the same numbers.
The formula
Three steps, the same ones the calculator runs:
- Concentration = mg in the vial ÷ mL of diluent. 10 mg in 2 mL is 5 mg/mL (5,000 mcg/mL).
- Volume = amount wanted ÷ concentration. 500 mcg at 5,000 mcg/mL is 0.1 mL.
- Units = volume in mL × 100 on a U-100 syringe. 0.1 mL is 10 units.
Aliquots per vial = total mcg in the vial ÷ mcg per aliquot, rounded down. 10 mg (10,000 mcg) at 500 mcg gives 20.
Worked example
5 mg in 2 mL of bacteriostatic water is 2.5 mg/mL, or 2,500 mcg/mL. A 250 mcg aliquot is 0.1 mL, which reads as 10 units on a U-100 syringe. The vial gives 20 such aliquots. Halve the diluent and the same aliquot becomes 5 units, harder to read; double it and it becomes 20 units.
A larger vial works the same way. 40 mg in 3 mL is 13.33 mg/mL; 2 mg of that is 0.15 mL, or 15 units, and the vial holds 20 aliquots of 2 mg.
Worked examples by vial size
- 5 mg vial (BPC-157, TB-500) in 2 mL: 2.5 mg/mL. 250 mcg is 0.1 mL, 10 units; the vial gives 20 aliquots.
- 10 mg vial (KPV, PT-141, Semax, Selank, DSIP, Tesamorelin) in 2 mL: 5 mg/mL. 500 mcg is 0.1 mL, 10 units; 1 mg is 20 units.
- 40 mg vial (MOTS-c, Retatrutide) in 3 mL: 13.33 mg/mL. 1 mg is 7.5 units, 2 mg is 15 units and 5 mg is 37.5 units.
- 50 mg vial (GHK-Cu) in 3 mL: 16.67 mg/mL. 1 mg is 6 units, 2 mg is 12 units.
- 50 mg vial (Epitalon) in 3 mL: 16.67 mg/mL. 5 mg is 30 units and 10 mg is 60 units.
Each is one click away in the presets above. The reconstitution chart gives the full grid.
Reading a U-100 insulin syringe
U-100 means 100 units per millilitre, so every unit is 0.01 mL. On a 1 mL syringe the numbered marks are usually every 10 units with small ticks every 2; on 0.5 mL and 0.3 mL syringes the ticks are every unit, which is why the smaller barrels are better for readings under about 20 units. Read the volume at the flat front edge of the plunger seal, not the tip of the cone.
Choosing how much water to add
There is no single right volume; it is a trade-off. More diluent gives a lower concentration and larger, easier-to-read volumes, but more aliquots of liquid to keep cold and a vial that fills up faster. Less diluent gives a stronger solution and smaller volumes that are harder to measure precisely. Most laboratories aim for the amount they measure most often to land between 10 and 50 units. Use the water finder to hit a specific reading, and keep the total within what the vial holds; our sealed vials are 3 mL glass.
Common mistakes
- Mixing up mcg and mg. 1 mg is 1,000 mcg. A thousand-fold error is the classic slip.
- Reading units as mL. 10 units is 0.1 mL, not 10 mL.
- Using a U-40 scale. The unit figures here assume U-100.
- Entering the blend total. For a two-compound vial, enter the milligrams of one component.
- Forgetting the label. Write the date and concentration on the vial when you reconstitute it.
Reconstitution notes
Let the vial reach room temperature. Swab the stopper with an alcohol swab. Add the diluent slowly down the inside wall of the vial, not onto the powder. Swirl gently; don't shake. Store the solution at 2 to 8 °C and use it within the period on the product page. The full method is in our guide, how to reconstitute peptides, and storage is covered in how to store peptides.
Concentration table
Vial size against diluent volume. Each cell gives the concentration and how much one U-100 unit (0.01 mL) holds.
| Vial | 1 mL | 2 mL | 3 mL | 5 mL |
|---|---|---|---|---|
| 2 mg | 2 mg/mL20 mcg per unit | 1 mg/mL10 mcg per unit | 0.67 mg/mL6.7 mcg per unit | 0.4 mg/mL4 mcg per unit |
| 5 mg | 5 mg/mL50 mcg per unit | 2.5 mg/mL25 mcg per unit | 1.67 mg/mL16.7 mcg per unit | 1 mg/mL10 mcg per unit |
| 10 mg | 10 mg/mL100 mcg per unit | 5 mg/mL50 mcg per unit | 3.33 mg/mL33.3 mcg per unit | 2 mg/mL20 mcg per unit |
| 15 mg | 15 mg/mL150 mcg per unit | 7.5 mg/mL75 mcg per unit | 5 mg/mL50 mcg per unit | 3 mg/mL30 mcg per unit |
| 20 mg | 20 mg/mL200 mcg per unit | 10 mg/mL100 mcg per unit | 6.67 mg/mL66.7 mcg per unit | 4 mg/mL40 mcg per unit |
| 30 mg | 30 mg/mL300 mcg per unit | 15 mg/mL150 mcg per unit | 10 mg/mL100 mcg per unit | 6 mg/mL60 mcg per unit |
| 40 mg | 40 mg/mL400 mcg per unit | 20 mg/mL200 mcg per unit | 13.33 mg/mL133.3 mcg per unit | 8 mg/mL80 mcg per unit |
| 50 mg | 50 mg/mL500 mcg per unit | 25 mg/mL250 mcg per unit | 16.67 mg/mL166.7 mcg per unit | 10 mg/mL100 mcg per unit |
| 100 mg | 100 mg/mL1,000 mcg per unit | 50 mg/mL500 mcg per unit | 33.33 mg/mL333.3 mcg per unit | 20 mg/mL200 mcg per unit |
Units to mL
| U-100 mark | Volume | Fits a |
|---|---|---|
| 1 units | 0.01 mL | any size |
| 2 units | 0.02 mL | any size |
| 5 units | 0.05 mL | any size |
| 10 units | 0.1 mL | any size |
| 15 units | 0.15 mL | any size |
| 20 units | 0.2 mL | any size |
| 25 units | 0.25 mL | any size |
| 30 units | 0.3 mL | any size |
| 40 units | 0.4 mL | 0.5 mL or 1 mL |
| 50 units | 0.5 mL | 0.5 mL or 1 mL |
| 75 units | 0.75 mL | 1 mL syringe |
| 100 units | 1 mL | 1 mL syringe |
mcg and mg
100 mcg = 0.1 mg · 250 mcg = 0.25 mg · 500 mcg = 0.5 mg · 1,000 mcg = 1 mg · 2,500 mcg = 2.5 mg
Questions
Four things: the concentration of the solution (peptide in the vial divided by the diluent added), the volume that contains a target amount, that volume as units on a U-100 insulin syringe (100 units = 1 mL), and how many aliquots of that size the vial holds.
You can't convert milligrams to millilitres directly; you need the concentration first. Divide the milligrams in the vial by the millilitres of diluent to get mg/mL, then divide the amount you want by that concentration. 2 mg wanted from a 10 mg vial in 2 mL (5 mg/mL) is 0.4 mL.
10 units. A U-100 syringe is marked in units of 0.01 mL, so 1 mL is 100 units, 0.5 mL is 50 units and 0.25 mL is 25 units. The units to mL table lists the common marks.
1 milligram (mg) is 1,000 micrograms (mcg, sometimes written µg). 250 mcg is 0.25 mg. Mixing the two up is the most common calculation error, so the calculator lets you switch units on the target amount and converts the number for you.
Enough that the volume you will measure is easy to read on the syringe, usually 10 to 50 units, and no more than the vial holds (our vials take about 3 mL). Adding more water lowers the concentration and makes each measured volume larger; it doesn't change the total peptide in the vial. The water finder works the volume out backwards from the reading you want.
No. The milligrams in the vial are fixed. Water only changes the concentration, so the same amount of peptide sits in a larger or smaller volume.
The unit readout assumes U-100, the standard insulin syringe in the UK (100 units = 1 mL). On a U-40 scale 40 units = 1 mL, so use the millilitre figure instead of the unit figure. Our insulin syringes are 1 mL U-100.
Yes, one component at a time. For a vial holding two compounds, enter the milligrams of the component you are interested in; the concentration and volume shown are for that component only. A 10 mg vial of 5 mg + 5 mg is entered as 5 mg for either half.
No. People often search for a peptide dosage calculator, but this tool only does the arithmetic of solutions: concentration, volume and syringe units for an amount you choose. It doesn't recommend amounts for any use, and our products are supplied for laboratory research only.
The same three steps. 40 mg in 3 mL is 13.33 mg/mL. Divide the amount you want by that: 1 mg is 0.075 mL, which reads as 7.5 units on a U-100 syringe. Use 2 mL instead and the solution is 20 mg/mL, so 1 mg is 0.05 mL, or 5 units. The reconstitution chart lists these for every common vial size.
A ready-made table of the arithmetic: for a given vial size and volume of water, how many syringe units a given amount reads as. Our reconstitution chart covers the common vial sizes (5, 10, 40, 50 and 100 mg) and amounts from 100 mcg to 5 mg. For any other combination, use the calculator above.
No. A sealed pre-filled pen, such as the retatrutide pen, is already a solution at a concentration stated by the manufacturer, so there is nothing to reconstitute. The calculator is for freeze-dried powder in a vial.
This one. It uses millilitres, milligrams and micrograms, assumes the U-100 insulin syringes sold in the UK, and has presets for the vials we hold in UK stock. It is free, needs no sign-up and can be embedded on other sites.
Yes. Copy the embed code in the embed section. It loads the same calculator in a frame, works on mobile and stays up to date.