Peptide Tracker

Peptide Reconstitution Calculator

Turn the numbers on your vial and the dose you were given into a calculated syringe draw. Enter three values and get units, mL, concentration and doses per vial in seconds. Free, no account, works on any device.

Free forever · No sign-up · U-100 syringe math · Shows its formula

1 mL / 100 units

Every U-100 insulin syringe uses the same scale (1 unit = 0.01 mL), so your unit count is the same on any size. Smaller barrels just space the lines further apart for easier reading.

Use the half-life calculator. Log this dose and get a reminder for the next one.

The total peptide in the vial, printed on the label (for example, 5 mg or 10 mg).

Step 2: Bacteriostatic water added

mL

The total liquid you added to the vial. More water makes each draw larger and easier to measure. It does not change how much peptide is in the vial.

Total amount mode assumes the final solution volume equals the water added. Dissolved powder can increase the final volume. If your product instructions specify a concentration after mixing, enter that concentration in Strength mode.

Step 3: Your dose

Enter the dose from your prescriber or qualified source. This tool does the math, not the dosing.

Enter the amount and volume to see the draw.

Reset

For reference arithmetic only. Double-check every result and confirm it with a qualified clinician.

How to use the calculator

Enter three numbers to calculate your draw.

  1. Enter what's in your vial. Use the total amount printed on the label (mg, mcg or IU). If your vial is already mixed, switch to Strength and enter its concentration instead.
  2. Enter the bacteriostatic water you added. Use the total mL you put in the peptide vial, not the size of the bacteriostatic water vial.
  3. Enter your dose. Use the dose you were given by your prescriber or qualified source, and set the matching unit.

Your result shows the units to draw on a U-100 insulin syringe, the same amount in mL, the concentration, and how many full doses the vial holds. Tap Show the math to see your inputs alongside the worked examples.

Mixing a blend? Tap Add another compound and enter each one's amount and dose. The calculator shows each compound's calculated amount per draw.

How the math works

The calculator turns your vial into one number, its concentration, then divides your dose by it. Every step is shown so you can check it by hand.

  1. 1. Concentration.

    Concentration is the amount of peptide per mL of the final solution.

    Concentration (mg/mL) = vial amount (mg) ÷ final volume (mL)

    Total amount mode assumes the final solution volume equals the water added. Dissolved powder can increase the final volume. If your product instructions specify a concentration after mixing, enter that concentration in Strength mode.

  2. 2. Volume to draw.

    Your dose divided by the concentration gives the volume.

    Draw (mL) = dose (mg) ÷ concentration (mg/mL)

  3. 3. Syringe units.

    On a U-100 insulin syringe, 100 units = 1 mL.

    Units = draw (mL) × 100

  4. 4. Doses per vial.

    Total in the vial divided by one dose, rounded down to full doses.

    Doses per vial = vial amount ÷ dose, rounded down

Worked examples (arithmetic only, not dosing suggestions)

Vial Water Concentration Dose Draw Doses per vial
5 mg 2 mL 2.5 mg/mL (25 mcg per unit) 250 mcg 10 units (0.10 mL) 20
10 mg 1 mL 10 mg/mL (100 mcg per unit) 2.5 mg 25 units (0.25 mL) 4
10 mg 2 mL 5 mg/mL (50 mcg per unit) 2.5 mg 50 units (0.50 mL) 4
Pre-mixed, 2 mg/mL Not needed 2 mg/mL (20 mcg per unit) 500 mcg 25 units (0.25 mL) Depends on fill volume

Compare the two 10 mg examples: same vial, same dose, but doubling the water doubles the draw. The amount of peptide delivered is identical.

Working backward.

To check what a draw delivers, multiply units by mcg per unit.

At 25 mcg per unit, a 15-unit draw is 375 mcg.

Quick shortcut.

mcg per unit = (vial mg × 1,000) ÷ (water mL × 100).

Divide your dose in mcg by that number to get units.

Units explained

Mixing up units can lead to dosing errors. Here is what each unit means.

  • mg and mcg: 1 mg = 1,000 mcg. A 5 mg vial holds 5,000 mcg, and a 250 mcg dose is 0.25 mg. Labels sometimes write mcg as µg.
  • IU (international units): a measure of biological activity, defined separately for each substance. There is no universal IU to mg conversion, so keep the vial and dose in IU together.
  • mL: the volume of liquid. Your water amount and your draw are both in mL.
  • Syringe units: marks on a U-100 insulin syringe. 1 unit = 0.01 mL, so 100 units = 1 mL. A syringe "unit" is a volume, not an IU, even though both are called units.

Syringe sizes

Syringe Capacity Typical markings Best for
0.3 mL U-100 30 units 1-unit (some 0.5-unit) Small draws, finest reading
0.5 mL U-100 50 units 1-unit Mid-size draws
1 mL U-100 100 units 2-unit Larger draws
3 mL standard 3 mL 0.1 mL, no unit marks Read in mL, not units

The unit count for a dose is the same on every U-100 syringe. Only the capacity and line spacing change.

Check for U-100. U-40 syringes also exist, mostly for veterinary use. Their markings don't match this math. Only use these results with syringes labeled U-100.

Choosing a water volume

Pick a water volume that lands your draw in an easy-to-read range, usually 5 to 50 units. Water changes how the dose is measured, never how much peptide is in the vial.

  • More water = lower concentration = bigger draws. Easier to measure small doses, but uses more syringe capacity.
  • Less water = higher concentration = smaller draws. Fits larger doses in one syringe, but tiny draws are harder to read.
  • Stay within the vial. Don't add more liquid than the vial can hold. Many vials top out at 2 to 3 mL.
  • Keep it consistent. Write the water volume on the vial label so every future draw uses the same math.

Reference table (how water changes the math, not a dosing guide)

Vial Water mcg per unit Units per 100 mcg Units per 1 mg
5 mg 1 mL 50 2 20
5 mg 2 mL 25 4 40
5 mg 3 mL 16.7 6 60
10 mg 1 mL 100 1 10
10 mg 2 mL 50 2 20
10 mg 3 mL 33.3 3 30

If your draw keeps landing under 5 units, a more dilute mix or a 0.3 mL syringe makes it easier to read. Confirm any change to how you mix with your provider.

Mixing and storage basics

Reconstitution means adding liquid, usually bacteriostatic water, to a freeze-dried (lyophilized) powder so it can be measured. Always follow the instructions from your prescriber, pharmacy or product labeling first.

General handling

  1. Wash your hands and wipe both vial stoppers with an alcohol swab.
  2. Draw the planned amount of bacteriostatic water into a new, sterile syringe.
  3. Add the water slowly, aimed down the inside wall of the vial rather than straight onto the powder.
  4. Swirl or roll gently until dissolved. Don't shake hard.
  5. Label the vial with the date mixed and the water volume you added.

Storage

  • Refrigerate after mixing (2 to 8 °C / 36 to 46 °F) and protect from light, unless your labeling says otherwise.
  • Don't freeze a mixed vial unless the labeling allows it.
  • How long a mixed vial stays usable varies by substance. Follow the labeling or your pharmacist.
  • Use a new sterile needle and syringe for every injection. Never reuse or share them.
  • Don't use a solution that looks cloudy, discolored or has particles, unless the labeling says that's expected.

Track it. The free Peptide Tracker app logs your vials, mix dates, doses and injection sites so you always know what's left and when you mixed it.

Common mistakes to avoid

  • Mixing up mg and mcg.

    A 1,000x error. Check the unit toggle on both the vial and the dose.

  • Confusing IU with syringe units.

    They are different things. IU measures activity; syringe units measure volume.

  • Entering the water vial size.

    Enter the mL you actually added to the peptide vial, not the size of the bacteriostatic water vial.

  • Using a non-U-100 syringe.

    U-40 or unmarked syringes won't match these results.

  • Changing water mid-vial.

    If you mix a new vial with a different volume, update the calculator. The old unit count no longer applies.

  • Forgetting blends.

    In a blend, one draw delivers every compound in the vial. Check each compound's amount per draw.

  • Reading between lines on a large syringe.

    Small draws on a 1 mL syringe are hard to read. A smaller barrel spaces the lines further apart.

FAQ

What does a peptide reconstitution calculator do?

It converts the dose you were given into the calculated volume to draw. You enter the amount in the vial, the water you added and your dose, and it returns syringe units, mL, concentration and doses per vial. It does not tell you what dose to take.

How many units should I draw?

It depends on three numbers: the amount in your vial, the water you added and your dose. Enter all three above for your calculated unit mark. For example, a 5 mg vial mixed with 2 mL works out to 25 mcg per unit, so a 250 mcg dose is 10 units.

How many mL is 10 units on an insulin syringe?

0.1 mL. On a U-100 syringe, 1 unit = 0.01 mL, so 10 units = 0.1 mL, 50 units = 0.5 mL and 100 units = 1 mL.

How much bacteriostatic water should I add?

Enough to make your dose easy to measure without overfilling the syringe or the vial. Many people use 1 to 3 mL. Follow any volume your prescriber or labeling specifies. See "Choosing a water volume" above for how each choice changes the math.

Does adding more water make my dose weaker?

No. The vial holds the same amount of peptide no matter how much water you add. More water spreads it through more liquid, so you draw more units to get the same dose.

What is bacteriostatic water?

Bacteriostatic water for injection is sterile water containing benzyl alcohol as a preservative to inhibit bacterial growth. Use the diluent specified by your product labeling, pharmacist or prescriber.

Can I use sterile water or saline instead?

Sterile water has no preservative, so it's generally meant for single use. Some products specify a particular diluent. Use whatever your prescriber, pharmacy or product labeling specifies.

How do I convert mg to mcg?

Multiply mg by 1,000. 5 mg = 5,000 mcg and 0.25 mg = 250 mcg. To go from mcg to mg, divide by 1,000. The calculator handles this automatically when you pick the unit.

Can I convert IU to mg?

Not with a universal formula. IU is defined separately for each substance, so the conversion depends on the product. Enter both the vial and the dose in IU and the calculator will keep the math consistent.

Are syringe units the same as IU?

IU and U-100 syringe units are commonly confused. IU measures biological activity. U-100 syringe units measure volume, with each syringe unit equal to 0.01 mL.

Which insulin syringe size should I use?

Any U-100 syringe gives the same unit count for a dose. A 0.3 mL (30 unit) syringe is easiest for small draws, a 0.5 mL (50 unit) for mid-size and a 1 mL (100 unit) for larger ones. Make sure the draw fits the syringe's capacity.

What if my draw isn't a whole number of units?

If your calculated draw falls between syringe markings, ask your pharmacist or prescriber how to measure the prescribed dose. Confirm any change to the dose or mixing instructions with them first.

How many doses are in my vial?

Divide the total amount in the vial by one dose. The calculator shows this as full doses. Real-world yield can be slightly lower because a little liquid stays in the vial and needle.

My vial label shows mg/mL. What do I enter?

Switch Step 1 to Strength and enter that concentration. You don't need to enter water in this mode.

How do I calculate a blend in one vial?

Tap Add another compound and enter each one's amount. Every draw delivers all compounds together, so the calculator shows how much of each is in a single draw.

Does this work for GLP-1 and TRT vials?

The math works for any liquid measured in mg/mL or mcg/mL. Use Strength mode for solutions that come pre-mixed. Prefilled pens are measured in clicks or preset doses, not syringe units, so follow the pen's instructions instead.

How long does a mixed peptide last?

It varies by substance. Most mixed vials are kept refrigerated and protected from light, but shelf life after mixing differs. Follow your product labeling or ask your pharmacist.

Is this calculator medical advice?

No. It's a reference tool for arithmetic. It doesn't recommend doses, confirm a substance is right for you or replace a clinician. Get your dose and protocol from a licensed provider.

Do I need an account?

No. The calculator is free with no sign-up.

Can I save my calculations?

The calculator does not save your numbers. To keep a record of every dose, vial, and mix date, log in on the web or use the free Peptide Tracker app.

This calculator is for educational reference and arithmetic only. It uses the values you enter and does not recommend doses, protocols or treatments, or confirm that any substance is appropriate or legal for you. Peptide Tracker is not a medical service and does not provide medical advice. Verify every result and talk to a licensed healthcare provider before you start, stop or change any medication, peptide or supplement.