Health
Peptide Reconstitution Calculator
Enter the peptide amount in the vial, the bacteriostatic water you added, and your target dose. Get the exact number of insulin-syringe units to draw, the volume in mL, the concentration, and how many doses the vial holds — results update live, with the working shown.
Reconstitute a vial
mg · mLmg
mL
Desired dose
Insulin syringe
Draw to this mark · U-100
10units
0.1 mL on the barrel · 20 doses per vial
volume to draw
0.1 mL
doses per vial
20
concentration
2.5 mg/mL
concentration
2,500 mcg/mL
Updates live · units rounded to the nearest 0.1
Try a common setup
No sign-up · Free
Please read
This tool performs unit-conversion arithmetic only. It is provided for general informational and research purposes and is not medical advice, not a dosing recommendation, and not a substitute for a qualified healthcare professional. It does not tell you what to take, how much, or whether any substance is safe or appropriate for you. Reconstitution and handling of any pharmaceutical or research compound should follow the guidance of a licensed clinician and applicable law. Always verify every number independently before relying on it.
The basics
What reconstitution actually is
A lyophilized peptide ships as a dry powder so it stays stable. To measure a dose you first dissolve it into a liquid of known strength. Two numbers come out of that step — the concentration of the solution and the volume you draw — and everything else follows from them.
concentration = mass ÷ volume
Concentration is mass over volume
Divide the peptide mass by the water volume you added. This is the strength of the solution — how much peptide sits in each millilitre — and it never changes until you add more liquid.
5 mg ÷ 2 mL = 2.5 mg/mL = 2500 mcg/mL
volume = dose ÷ concentration
Volume is dose over concentration
The liquid you actually draw is the dose divided by the concentration. A stronger solution means a smaller volume for the same dose; a weaker one means more liquid to pull.
250 mcg ÷ 2500 mcg/mL = 0.1 mL
The syringe
How to read insulin-syringe units
Insulin syringes are marked in units, not millilitres, and the conversion depends on which barrel you have. The number after the “U” is how many units fit in one millilitre.
1 mL = 100 units
U-100 (the common one)
The standard insulin syringe. One millilitre is 100 marks, so 0.1 mL reads as 10 units. Multiply your volume in mL by 100 to get units.
1 mL = 50 units
U-50
A 0.5 mL barrel marked to 50 units, giving finer spacing for small volumes. The same 0.1 mL reads as 5 units here.
1 mL = 40 units
U-40
An older scale, 40 units per millilitre. The same 0.1 mL reads as 4 units. Always check the “U” number printed on your barrel before reading a mark.
Method
How to work it out by hand
Four steps take you from a vial to a number of units on the barrel.
- 1
Find the concentration
Multiply the peptide mass in mg by 1000 to get micrograms, then divide by the water volume in mL.
5 mg × 1000 ÷ 2 mL = 2500 mcg/mL - 2
Find the volume for your dose
Divide the dose in mcg by that concentration. The answer is the volume of liquid you need to draw.
250 mcg ÷ 2500 mcg/mL = 0.1 mL - 3
Convert volume to units
Multiply the volume by the units-per-mL of your barrel — 100 for U-100, 50 for U-50, 40 for U-40.
0.1 mL × 100 = 10 units (U-100) - 4
Check doses per vial
Divide the total peptide in mcg by the dose to see how many shots the vial holds — independent of the water you added.
5000 mcg ÷ 250 mcg = 20 doses
Worked examples
The same math across vials
One formula runs from a small 2 mg vial to a 10 mg vial — only the numbers change. Each tab works the full sum end to end.
Given 5 mg peptide + 2 mL water, draw 250 mcg on a U-100 syringe
Concentration: 5 × 1000 ÷ 2 = 2,500 mcg/mL
Volume: 250 ÷ 2,500 = 0.1 mL
Units: 0.1 × 100 = 10 units
Doses per vial: 5 × 1000 ÷ 250 = 20
Draw to 10 units (0.1 mL)
Quick chart
Common mg + mL → concentration
The concentration you land on for the usual vial sizes and water volumes, in both mg/mL and mcg/mL. Find your row, then divide your dose by the mcg/mL figure to get the volume.
| Peptide | Water added | Concentration | Per mcg/mL |
|---|---|---|---|
| 2 mg | 1 mL | 2 mg/mL | 2,000 mcg/mL |
| 2 mg | 2 mL | 1 mg/mL | 1,000 mcg/mL |
| 2 mg | 3 mL | 0.667 mg/mL | 666.67 mcg/mL |
| 5 mg | 1 mL | 5 mg/mL | 5,000 mcg/mL |
| 5 mg | 2 mL | 2.5 mg/mL | 2,500 mcg/mL |
| 5 mg | 3 mL | 1.667 mg/mL | 1,666.67 mcg/mL |
| 10 mg | 1 mL | 10 mg/mL | 10,000 mcg/mL |
| 10 mg | 2 mL | 5 mg/mL | 5,000 mcg/mL |
| 10 mg | 3 mL | 3.333 mg/mL | 3,333.33 mcg/mL |
| 15 mg | 1 mL | 15 mg/mL | 15,000 mcg/mL |
| 15 mg | 2 mL | 7.5 mg/mL | 7,500 mcg/mL |
| 15 mg | 3 mL | 5 mg/mL | 5,000 mcg/mL |
| 30 mg | 1 mL | 30 mg/mL | 30,000 mcg/mL |
| 30 mg | 2 mL | 15 mg/mL | 15,000 mcg/mL |
| 30 mg | 3 mL | 10 mg/mL | 10,000 mcg/mL |
Why it matters
Why the arithmetic matters
Three places where getting the concentration and the unit conversion right is the whole ballgame.
readable marks
Choosing the dilution
The water volume is a free choice that decides where a dose lands on the barrel. Picking it well turns an awkward fraction into a clean, easy-to-read number of units.
right barrel
Reading the right scale
A U-40 and a U-100 syringe show different numbers for the same liquid. Knowing which barrel you hold is what stands between the volume on paper and the mark you read.
vial planning
Budgeting a vial
Doses-per-vial tells you how long a vial lasts and what each dose costs, so you can plan and compare vial sizes on the same footing.
Worth knowing
Common mistakes and edge cases
The errors that throw the number off — and the facts that keep the arithmetic honest.
units ≠ mL
Units are not millilitres
The barrel is marked in units, not mL. Drawing “0.1” when you mean 0.1 mL versus 10 units is a tenfold error on a U-100 syringe — always convert through the units-per-mL.
mg vs mcg
Mind the thousand
One milligram is 1000 micrograms. Most peptide doses are quoted in mcg while vials are labelled in mg, so a single missed factor of 1000 is the most common slip.
water ≠ dose
Water sets volume, not dose
Adding more water does not give you more peptide — it spreads the same mass over more liquid, so you draw a larger volume for the identical dose.
check the U
Confirm the barrel scale
U-40 syringes still exist. Reading a U-40 barrel as if it were U-100 changes every number by more than double. Check the printed “U” before you trust a mark.
fractions are normal
Half-units happen
A dose rarely lands on a whole unit. A result of 12.5 units is fine; if it bothers you, change the water volume to shift where it falls.
round carefully
Rounding adds up
Rounding the volume too early compounds across a vial. Carry full precision through the math and round only the final unit reading.
Related health math
Other body-and-dose tools
Concentration math is one piece of the picture. A couple of other quick calculators round out the everyday numbers.
FAQ
Common questions
Reconstituting means turning a dry, freeze-dried (lyophilized) peptide back into a liquid by adding a sterile solvent — usually bacteriostatic water. The powder dissolves into a solution of a known strength, called the concentration, which is what lets you measure out a precise dose. The peptide mass never changes; you are only choosing how much liquid to dilute it into.
On a standard U-100 insulin syringe, 1 mL is marked as 100 units, so units = volume in mL × 100. Working from the dose directly, units = dose in mcg × water in mL ÷ (peptide in mg × 10). For example, a 5 mg vial reconstituted with 2 mL gives 2500 mcg/mL; a 250 mcg dose is 0.1 mL, which is 10 units on a U-100 syringe.
The number is how many units the barrel marks per millilitre. A U-100 barrel reads 100 units per mL, a U-50 reads 50 per mL, and a U-40 reads 40 per mL. The same 0.1 mL of liquid is 10 units on a U-100, 5 units on a U-50, and 4 units on a U-40, so you must read the number off the syringe you actually own before drawing.
Concentration is the peptide mass divided by the water you added. In micrograms per millilitre it is peptide_mg × 1000 ÷ water_mL. A 10 mg vial in 2 mL is 10 × 1000 ÷ 2 = 5000 mcg/mL (5 mg/mL). Adding more water lowers the concentration, so each dose takes a larger, easier-to-measure volume.
No. The amount of water changes the concentration and therefore the volume you draw, but not the actual dose of peptide. More water means you draw more liquid for the same milligrams; less water means you draw less. People often add more water specifically to make small doses fall on a readable number of syringe units.
Divide the total peptide by the dose, in matching units. In micrograms it is peptide_mg × 1000 ÷ dose_mcg. A 5 mg vial dosed at 250 mcg holds 5000 ÷ 250 = 20 doses. The water you add does not affect this — only the total peptide and the dose size do.
There is no single correct volume — the water is a dilution choice, not a fixed amount, and common volumes are 1, 2, or 3 mL. More water spreads the same peptide over more liquid, which can make a small dose land on a cleaner number of syringe units and easier to measure. This calculator shows the resulting concentration and units for whatever volume you enter so you can compare options. It does not recommend a volume.
Because the dose, concentration, and barrel scale rarely divide into a whole number. A result like 12.5 units is normal. If a tidier number matters to you, changing the water volume shifts where the dose lands on the barrel — the calculator updates the units live as you do.
Keep going
Related calculators
Keep reading
Further reading
Health
How to Calculate BMI (Body Mass Index), With the Formula and Examples
BMI = weight in kilograms ÷ height in metres squared. If you measure in pounds and inches, BMI = 703 × weight (lb) ÷ height (in) squared. This guide shows both formulas worked end to end, the standard WHO category table, and what BMI can and cannot tell you.
Ugo Charles
Math
How to Calculate GPA (Grade Point Average), Step by Step
To calculate GPA, convert each letter grade to its point value on the 4.0 scale, multiply each by the course's credit hours to get quality points, sum those quality points, and divide by the total credit hours. This guide walks through the formula, a full worked example, weighted versus unweighted GPA, and cumulative GPA across semesters.
Ugo Charles
Finance
How CD Interest Is Calculated: APY, Compounding, and Penalties
CD interest follows A = P(1 + r/n)^(nt). Why banks quote APY and not the rate, how compounding frequency moves the total, and what breaking early costs.
Ugo Charles
Written by
UC
Author
Ugo CharlesBuilt and fact-checked against our editorial standards · Last updated June 2026
Did this solve your problem?