Peptide Calculator
Peptide reconstitution arithmetic: vial mass and bacteriostatic water give a concentration, and a dose you already have gives syringe units. Converts units only.
Peptide Calculator: with the default inputs, units to draw on the syringe is 5.
Read it off the vial label. This calculator takes the label at its word.
The volume of diluent you add to the vial.
A dose from a prescription or a product label. This calculator does not suggest one.
1 mg = 1,000 mcg. Mixing the two up is a thousandfold error.
On a syringe of the graduation set above. It is a volume, not a quantity of peptide.
- Volume to draw
- 0.05Millilitres. Units are just this volume read off the barrel.
- Concentration
- 5Milligrams of peptide per millilitre of solution.
- Micrograms per syringe unit
- 50What one mark on the barrel holds at this concentration.
- Whole doses of this size in the vial
- 40Before any loss in the needle, the stopper or the syringe.
Assumptions
- This calculator converts units. It does not recommend a dose, does not diagnose anything, and does not replace a clinician.
- Peptides of this kind are commonly sold labelled for research use and are not approved for human use without a prescription.
- The vial is assumed to hold exactly the mass printed on its label, and the powder is assumed to add no volume of its own — so the final volume is taken as the volume of diluent added.
- Syringe units are volume. One unit on a U-100 insulin syringe is 0.01 mL, per the FDA-approved labelling for U-100 insulin.
- 1 mg = 1,000 mcg.
- Doses per vial ignore residual volume left in the needle, the syringe and the stopper.
| Units drawn | Millilitres | Micrograms of peptide | Milligrams |
|---|---|---|---|
| 1 | 0.01 | 50 | 0.05 |
| 2 | 0.02 | 100 | 0.1 |
| 4 | 0.04 | 200 | 0.2 |
| 5 | 0.05 | 250 | 0.25 |
| 10 | 0.1 | 500 | 0.5 |
| 15 | 0.15 | 750 | 0.75 |
| 20 | 0.2 | 1,000 | 1 |
| 25 | 0.25 | 1,250 | 1.25 |
| 30 | 0.3 | 1,500 | 1.5 |
| 40 | 0.4 | 2,000 | 2 |
| 50 | 0.5 | 2,500 | 2.5 |
| 75 | 0.75 | 3,750 | 3.75 |
| 100 | 1 | 5,000 | 5 |
A conversion table, not a list of doses. Every row is the same arithmetic: units ÷ graduation × concentration.
How this is worked out
The formula
concentration (mg/mL) = peptide in the vial (mg) ÷ bacteriostatic water added (mL) volume to draw (mL) = dose (mg) ÷ concentration (mg/mL) syringe units = volume to draw (mL) × syringe graduation (units per mL) On a U-100 insulin syringe the graduation is 100 units per mL, so one unit is 0.01 mL. 1 mg = 1,000 mcg.
Open How it’s calculated above to see this worked through with your own numbers.
What you enter
- Peptide in the vial
- Read it off the vial label. This calculator takes the label at its word.from 0.01 to 1000 · defaults to 10
- Bacteriostatic water added
- The volume of diluent you add to the vial.from 0.05 to 50 · defaults to 2
- Dose you already have
- A dose from a prescription or a product label. This calculator does not suggest one.from 0.001 to 100000 · defaults to 250
- Dose is measured in
- 1 mg = 1,000 mcg. Mixing the two up is a thousandfold error.micrograms (mcg) · milligrams (mg)
- Syringe graduation(under More options)
- 100 for a standard U-100 insulin syringe, where 1 unit is 0.01 mL. U-40 syringes are veterinary and read completely differently.from 10 to 500 · whole numbers only · defaults to 100
What you get back
- Units to draw on the syringemain answer
- On a syringe of the graduation set above. It is a volume, not a quantity of peptide.
- Volume to draw
- Millilitres. Units are just this volume read off the barrel.
- Concentration
- Milligrams of peptide per millilitre of solution.
- Micrograms per syringe unit
- What one mark on the barrel holds at this concentration.
- Whole doses of this size in the vial
- Before any loss in the needle, the stopper or the syringe.
What this assumes
- This calculator converts units. It does not recommend a dose, does not diagnose anything, and does not replace a clinician.
- Peptides of this kind are commonly sold labelled for research use and are not approved for human use without a prescription.
- The vial is assumed to hold exactly the mass printed on its label, and the powder is assumed to add no volume of its own — so the final volume is taken as the volume of diluent added.
- Syringe units are volume. One unit on a U-100 insulin syringe is 0.01 mL, per the FDA-approved labelling for U-100 insulin.
- 1 mg = 1,000 mcg.
- Doses per vial ignore residual volume left in the needle, the syringe and the stopper.
About this calculator
This is unit arithmetic, not medical advice. It turns a vial's stated contents and the water you add into a concentration, and turns a dose you already have into the number of units on a syringe. It does not recommend a dose, and no number anywhere on this page is a suggested amount. It does not diagnose anything and it does not replace a clinician.
Peptides of this kind are commonly sold labelled for research use and are not approved for human use without a prescription. The FDA has warned companies that illegally sold unapproved drugs "falsely labeled 'for research purposes' or 'not for human consumption'", and notes that compounded drugs "are not FDA approved", meaning "the agency does not review compounded drugs for safety, effectiveness or quality before they are marketed". If you have a prescription, the instructions that came with it are the authority — not this page.
What the arithmetic is
Three numbers, two divisions, no judgement:
- Concentration is the peptide mass in the vial divided by the volume of bacteriostatic water you add. 10 mg into 2 mL is 5 mg/mL, or 5,000 mcg/mL.
- Volume to draw is the dose divided by that concentration. 250 mcg out of 5,000 mcg/mL is 0.05 mL.
- Syringe units are that volume read off the barrel. A U-100 insulin syringe is graduated at 100 units per millilitre — the FDA-approved label for U-100 insulin says "Injection: 100 units/mL (U-100)" and "Use only with a U-100 syringe" — so 0.05 mL is 5 units.
Note what the third step means: units are a volume, not a quantity of peptide. "10 units" means nothing until you know the concentration. Two vials reconstituted differently give completely different amounts at the same mark, which is the single most common way this goes wrong.
How to use it
Put the milligrams printed on the vial in the first field and the water you intend to add in the second. Enter the dose you have been given, taking care over mcg versus mg — they differ by a factor of a thousand, and the calculator will say so if the number you typed looks like the other unit. Change the syringe graduation only if you are not using a standard U-100 insulin syringe.
The chart shows the same dose drawn from the same vial reconstituted with different volumes of water. It is there to make one point: more diluent does not change the dose, it changes how many units that dose occupies. Small doses are easier to measure accurately when they sit further up the barrel.
Where it stops
It takes the vial label at face value. It cannot tell you whether the vial holds what it claims, whether the contents are sterile, or whether the peptide is what it says it is — and for products sold outside the regulated supply chain, none of that is assured. It says nothing about whether a dose is appropriate, about frequency, about interactions, or about whether any of this should be injected at all. Those are questions for a clinician, and the FDA has received "multiple reports of adverse events, some requiring hospitalization" from dosing errors with these products, so they are not questions to answer from a forum post.
Frequently asked questions
▸How many units is 250 mcg?
There is no answer without the concentration. Units are a volume: on a U-100 syringe one unit is 0.01 mL. At 5 mg/mL, 250 mcg is 0.05 mL, so 5 units. At 10 mg/mL the same 250 mcg is 2.5 units.
▸Does adding more bacteriostatic water change the dose?
No. It changes the concentration, so the same dose occupies more volume and more marks on the syringe. The amount of peptide is fixed by the vial.
▸What is the difference between bacteriostatic and sterile water?
Bacteriostatic Water for Injection has benzyl alcohol added as a preservative — the FDA label states 0.9% (9 mg/mL) or 1.1% (11 mg/mL) — which allows a vial to be entered more than once. Its label also says it is indicated only for diluting or dissolving drugs for injection, and carries the warning "NOT FOR USE IN NEONATES".
▸Does this calculator tell me what dose to take?
No. It converts a dose you already have into syringe units, and nothing on this page is a recommendation. Peptides of this kind are commonly sold labelled for research use and are not approved for human use without a prescription.
▸Why does it warn me about mcg and mg?
Because they differ by a factor of 1,000 and confusing them is the classic reconstitution error. If the number you typed looks like it belongs to the other unit, the calculator says so rather than quietly returning a figure that is a thousand times wrong.
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