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Peptide Calculator

Reconstituting a vial turns a mass of powder and a volume of water into a concentration — and then into a small, hard-to-read number of unit marks on a U-100 insulin syringe. That conversion is where mistakes happen, because micrograms, milligrams, millilitres and syringe units are four different scales and three of them look alike on a label.

This calculator does all three parts of the job in one place: choose a water volume, get the concentration, and convert an amount into units. It is arithmetic only — it never proposes an amount, and every field starts blank.

The math, before you use the tool

Concentration
mg/mL = vial (mg) ÷ bacteriostatic water (mL)
Volume to draw
mL = dose (mg) ÷ concentration (mg/mL)
Syringe units
units = volume (mL) × 100 [U-100: 100 marks = 1 mL]
Doses per vial
doses = vial (mg) ÷ dose (mg)
Water for a target mark
mL = (target units × vial mg) ÷ (dose mg × 100)

Everything below is these five lines and nothing else. 1 mg = 1000 mcg, and one unit mark on a U-100 syringe is 0.01 mL — so a unit count only means something once you know the concentration it was read at.

Read this before you use the calculator

This tool performs unit arithmetic on numbers you enter, and nothing else. It is not medical advice, it does not recommend a dose, and it is not a suggestion that you use any compound. Most of the peptides these calculators get used with are not FDA-approved for the purposes they are marketed for, are sold through a grey market where purity and labelling are not guaranteed, and many are prohibited in tested sport — check yours with the WADA prohibited-status checker. Any decision to use a compound, and any amount, must come from a licensed clinician who knows your history.

You already mixed the vial and want to know what a dose looks like on the syringe.
Dose you are working out
The number you were told to work out — this tool does not propose one. 1 mg = 1000 mcg.

Enter the vial size, the water you added, and the amount you are working out. Every field starts blank on purpose — this tool converts your numbers, it does not supply them.

This is arithmetic, not advice. Every figure above is derived only from the numbers you typed. Nothing here is a recommended dose, a claim that any compound is approved, safe, or effective, or a suggestion that you should use one. Confirm the vial label, the water volume, and the amount with a licensed clinician before you draw anything.

Worked examples

Real numbers, every step shown, so you can check the tool against a pen and paper. These illustrate the arithmetic — the amounts in them are inputs chosen to make the maths legible, not amounts anyone should use.

A 5 mg vial mixed with 2 mL, working out 250 mcg

  1. 1Concentration: 5 mg ÷ 2 mL = 2.5 mg/mL (2500 mcg/mL)
  2. 2One unit mark therefore carries 2500 ÷ 100 = 25 mcg
  3. 3Convert the amount: 250 mcg = 0.25 mg
  4. 4Volume: 0.25 mg ÷ 2.5 mg/mL = 0.1 mL
  5. 5Units: 0.1 mL × 100 = 10 units
  6. 6Doses per vial: 5 mg ÷ 0.25 mg = 20

10 units on a U-100 syringe · 20 draws from the vial

The same vial mixed with 1 mL instead — why water matters

  1. 1Concentration: 5 mg ÷ 1 mL = 5 mg/mL (5000 mcg/mL)
  2. 2Volume: 0.25 mg ÷ 5 mg/mL = 0.05 mL
  3. 3Units: 0.05 mL × 100 = 5 units
  4. 4Doses per vial: still 5 mg ÷ 0.25 mg = 20 — the water changed nothing here

5 units, not 10 — same vial, same amount, half the water

Adding a price: cost per draw

  1. 1A 5 mg vial mixed with 2 mL gives 20 draws at 250 mcg
  2. 2Vial price: $55
  3. 3Cost per draw: $55 ÷ 20 = $2.75

$2.75 per draw

Solving the water so 250 mcg lands on a round 20-unit mark

  1. 1Rearrange units = (dose mg ÷ (vial mg ÷ water mL)) × 100
  2. 2water mL = (target units × vial mg) ÷ (dose mg × 100)
  3. 3water mL = (20 × 5) ÷ (0.25 × 100) = 100 ÷ 25 = 4 mL
  4. 4Check the vial capacity first — 4 mL will not fit a 3 mL vial

4 mL of bacteriostatic water — if the vial physically holds it

Compound-specific versions

The arithmetic is identical for every compound — only the units people habitually work in change. These run the same engine with the vial strengths and default unit already set:

Frequently asked questions

How do you calculate a peptide dose in insulin-syringe units?
Three steps. First, concentration: divide the peptide mass in the vial (mg) by the bacteriostatic water you added (mL). Second, volume: divide the amount you are working out (converted to mg) by that concentration. Third, units: multiply the volume in mL by 100, because a U-100 insulin syringe puts 100 unit marks across 1 mL. Example: a 5 mg vial in 2 mL of water is 2.5 mg/mL; 250 mcg is 0.25 mg, which is 0.1 mL, which is 10 units.
Does adding more bacteriostatic water change how many doses a vial gives?
No. The vial holds a fixed mass of peptide, so doses per vial is vial mg divided by dose mg regardless of the water. What water changes is where a given amount lands on the syringe. A 5 mg vial at 250 mcg per draw is 20 draws whether you mix it with 1 mL or 3 mL — but 250 mcg reads as 5 units at 1 mL and 15 units at 3 mL.
How much bacteriostatic water should I add to a peptide vial?
There is no single correct volume; it is a choice about readability and vial capacity, not potency. Two constraints matter. The volume has to physically fit — many lyophilized peptide vials hold only 2 to 3 mL. And the amount you will draw should land on a mark you can read without squinting, which is what the 'Water to add' mode solves for: bacteriostatic water mL = (target units × vial mg) ÷ (dose mg × 100).
What is a U-100 insulin syringe unit in mL?
One unit is 0.01 mL. U-100 means the syringe is graduated for insulin at 100 international units per millilitre, so a 1 mL barrel carries 100 marks. That is a fixed volumetric relationship, which is why units on their own never describe an amount of peptide — the same 10 units carries a different mass at every concentration.
What if the calculator says the draw is more than 100 units?
It will not fit in one standard 1 mL U-100 syringe. That usually means the vial was mixed with more water than the amount you are working out suits, or a figure is wrong by a factor of 1000 because mcg and mg were swapped. Re-check the vial label and the number you were given rather than splitting the draw on your own judgement.
Is this peptide calculator medical advice?
No. It performs unit arithmetic on the numbers you type and never proposes an amount — every field starts blank on purpose. It is not medical advice, not dosing advice, and not a recommendation to use any compound. Most research peptides are not FDA-approved for the purposes they are marketed for, are sold on a grey market with unverified purity, and are prohibited in tested sport.
Where did the reconstitution and dosing calculators go?
They were merged into this page. The two tools ran nearly identical arithmetic under different names, which meant the same question had two answers in two places. Reconstituting a vial and working out a draw are one job in sequence, so both now live here behind a mode switch, and the old URLs redirect to this page.

The part a calculator cannot answer

A number on a syringe is the easy half. Whether a compound does anything in humans, whether it is legal to buy, and whether it will end a season are the questions worth your time:

Medical disclaimer: This content is for general educational purposes only and is not medical advice, diagnosis, or treatment. Always consult a licensed healthcare professional before starting, stopping, or changing any treatment.

This calculator converts units. It does not account for your health, the specific product in your hand, its actual purity, injection technique, or whether using it is appropriate at all. Nothing on this page states or implies that any compound is FDA-approved, safe, or effective. Talk to a licensed clinician before acting on any figure here.