How blend arithmetic works
draw volume (mL) = units ÷ 100
component in draw (mg) = component mg/mL × draw volume
All components share one volume of water, so they always move together. Doubling the water halves every component's amount per unit. Changing the reading changes all of them in proportion. That's why a blend calculator reports each component rather than a single number.
To find the reading for a target amount of one component, divide the target by that component's concentration and multiply by 100. The other components follow the ratio.
Examples
Two equal components
5 mg + 5 mg in 2 mL: each is 2.5 mg/mL. A 10-unit draw (0.1 mL) holds 0.25 mg of each, 0.5 mg in total.
Four components, unequal split
A KLOW-style label (GHK-Cu 50 + BPC-157 10 + TB-500 10 + KPV 10 mg) in 4 mL: 10 units holds 1.25 mg GHK-Cu, 0.25 mg BPC-157, 0.25 mg TB-500, 0.25 mg KPV. To reach 0.5 mg of BPC-157 takes 20 units, which also brings 2.5 mg of GHK-Cu. See the KLOW calculator and GLOW calculator.
Frequently asked questions
How do you calculate units for a peptide blend?
Divide each component’s mg by the water volume to get its own concentration. A draw of N units on a U-100 syringe is N ÷ 100 mL, and contains (component mg/mL × that volume) of each component. Example: 5 mg + 5 mg in 2 mL; 10 units (0.1 mL) holds 0.25 mg of each.
Can I measure one component of a blend separately?
No. Every draw contains all components in the ratio printed on the label. You can calculate the units needed to reach a target amount of one component, but the others come along in proportion.
Does the total mg on a blend label matter?
Only as a check. The arithmetic uses each component’s own mg. The total tells you the overall concentration and should equal the sum of the components.
Sources
- FDA alerts health care providers, compounders and patients of dosing errors associated with compounded injectable semaglutide products
- Bacteriostatic Water for Injection, USP (Hospira) — prescribing label
Links checked 2026-10-19.