Dilution calculator
Find out how much liquid to add to lower the strength of a solution you've already mixed, and check your new syringe units.
For your reference only. It converts the numbers you type. Your dose is set by your prescriber or by the product label you have.
- the single rule behind every dilution
- C1 x V1 equals C2 x V2
- Use 1 part mix and 3 parts water
- Example: 10 mg/mL ending at 2.5 mg/mL
With a dilution calculator, you can find how much original liquid and added water to use when weakening a solution that is already mixed. Diluting the medicine spreads it across a bigger volume, so you can read tiny doses more easily on your syringe. Your prescriber or pharmacist should approve any change to a medication's strength, and your prescriber always sets your dose.
The dilution calculator formula in plain words
The starting milligrams of medicine must equal the ending milligrams when you water down a liquid. Put simply, we multiply starting strength by starting volume, then match that with final strength times final volume.
We write this equation in standard math symbols as C1 x V1 = C2 x V2. Here, C means concentration in mg per mL, and V means volume in mL. The dosage calculator formula shows how concentration works with syringe math.
Worked example: peptide concentration calculator
Suppose your vial contains 10 mg per mL. You want 2 mL of liquid, with the strength cut to half, which is 5 mg per mL. We take the 5 mg per mL target strength and multiply it by the 2 mL target volume. The result is divided by 10 mg per mL, the starting strength.
The result is 1 mL of your original strong solution. Take 1 mL from the 10 mg per mL mix and mix it with 1 mL of diluent. The total is 2 mL at 5 mg per mL.
Units and dilution
Watering a solution down means drawing more units on a U-100 syringe to get the same dose; this syringe holds 100 units in 1 mL. With a mix at 10 mg per mL, 0.5 mg equals 0.05 mL, which is 5 units. Once you dilute it to 5 mg per mL, the same 0.5 mg dose needs 0.1 mL, or 10 units.
Powder mixing works differently
Use the 2-volume dilution method only when your medication is already a liquid. For a dry powder vial, divide the label's total milligrams by how many mL of water you add. The peptide reconstitution calculator is another option.
Questions people often ask
What is the meaning of C1V1 = C2V2?
The result of multiplying your starting concentration by your starting volume equals the result of multiplying your ending concentration by your ending volume. Because water doesn't add or remove medicine, the exact same milligrams appear on both sides of the equation.
Why do people dilute a peptide solution?
With a strong mix, small doses can fall on tiny numbers, such as 2.5 units; lining those up on a syringe barrel is hard. After dilution, the dose covers more unit marks on the syringe. Before any change to a prescribed vial, always check with your pharmacist or prescriber.
Which liquid should I use for dilution?
The choice of a safe liquid to mix with your drug is made by your medication label or pharmacist. Compare bacteriostatic versus sterile water to learn how preserved and single-use water differ. You can also check single-dose rules on the sterile water label from Fresenius Kabi.