How the calculator works

Last checked 2026-10-07. The formulas are public so anyone can check them.

The three formulas

strength (mg/mL) = peptide in vial (mg) ÷ water added (mL)
volume (mL) = dose (mg) ÷ strength (mg/mL)
units = volume (mL) × 100

The last line holds for U-100 insulin syringes, the kind marked in units, where 1 mL is 100 units. 1 mg is 1,000 mcg, so a dose entered in mcg is divided by 1,000 first.

Worked example. 10 mg in 2 mL is 5 mg/mL. A 250 mcg dose is 0.25 mg, and 0.25 ÷ 5 = 0.05 mL. 0.05 × 100 = 5 units.

Doses in the vial is the vial's mg divided by the dose in mg, rounded down.

Blends. The volume comes from the first peptide alone. The second peptide's dose is that volume times the second peptide's own strength (its mg ÷ the water).

Reading the syringe

A 1 mL syringe usually has a line every 2 units and a number every 10. 0.3 mL and 0.5 mL syringes usually have a line every unit and a number every 5. The drawing in the calculator follows those markings, and when an answer falls between two lines we name the nearest one.

0.3 mL · top mark 30 · 1 unit a line0510152025300.5 mL · top mark 50 · 1 unit a line051015202530354045501 mL · top mark 100 · 2 units a line0102030405060708090100
The three sizes, drawn to the same scale by the calculator's own code. The top mark is the quickest way to tell them apart.

The safety checks

CheckWhen it showsLevel
Dose above vialThe dose is more than the whole vial contains. Usually mg typed for mcg.Stop
Over capacityThe answer is more units than the chosen syringe holds (30, 50 or 100).Stop
Likely unit slipA dose entered in mg is 100 or more.Caution
Too small to drawThe answer is under 2 units.Caution
Between linesThe answer doesn't sit on a printed line. We name the nearest one.Info

Every formula and check has automated tests, including the 10x (units vs mL) and 1,000x (mg vs mcg) slips. The worked tables on each page are generated by the same code as the calculator, so they can't drift apart.

Mixing (reconstitution)

  1. Wash your hands. Wipe both vial tops with an alcohol swab.
  2. Draw up the amount of bacteriostatic water you chose.
  3. Let the water run slowly down the inside wall of the peptide vial, not onto the powder.
  4. Swirl gently or roll until clear. Don't shake.
  5. Write the date and the water amount on the vial. Keep it in the fridge.

Any instructions from your prescriber or pharmacist come first.

Why we show units, mL and a drawing

The FDA has reported people drawing many times their intended dose of compounded GLP-1 medicines after confusing units, mL and mg (FDA alert). Showing the same answer three ways makes a mix-up easier to spot.

What the calculator doesn't do

It doesn't suggest a dose, say whether a dose is right for you, or tell you where to get anything. It does maths on numbers you already have.

Corrections log

Every fix to a formula, check or published number is listed here with the date. Spotted a mistake? Email hello@doseclear.com.

  • 7 Oct 2026: launched. No corrections yet.