Calculator
Seven common peptide calculator mistakes
Reconstitution math is simple, which is why mistakes are easy to miss. Almost every error falls into one of seven patterns, and the worst of them produce results that are off by a factor of 10, 100 or 1,000.
1. Confusing micrograms and milligrams
1 mg is 1,000 mcg. Typing 250 into a field expecting milligrams instead of micrograms gives an answer 1,000 times too large. Our calculator shows the unit next to every input and lets you switch, but the cheapest safeguard is to say the unit out loud.
2. Treating units as millilitres
On a U-100 syringe, 100 units is 1 mL, so 10 units is 0.1 mL. “Draw 10” means nothing without the unit. Results that read “10 mL” for a draw from a 2 mL vial are a sign of this error.
3. Assuming every syringe is U-100
U-100 is the standard insulin syringe in the US, but U-40 syringes exist (used in veterinary insulin and some other countries). On a U-40 syringe, 40 units is 1 mL. Using a U-100 calculation with a U-40 syringe gives a volume 2.5 times too large.
4. Ignoring syringe capacity
A 0.3 mL syringe holds 30 units. If the math says 45 units, it will not fit. The calculator warns when a draw exceeds the selected syringe.
5. Using the label mass instead of net content
The label states gross powder weight. If the COA reports 80% net peptide content, a “10 mg” vial holds about 8 mg of peptide, and every concentration based on 10 mg is 25% high. Enter the corrected mass for accurate figures. See reading a COA.
6. Blend math done per component
In a blend, all components share the same water. A 20 mg vial with 10 mg of each of two peptides, mixed in 2 mL, contains 5 mg/mL of each, not 10 mg/mL of the total. Use the blend tab, which reports each component per draw.
7. Rounding too early
Rounding concentration to one decimal before dividing again compounds error. Keep full precision until the final step, then round to what the syringe can actually measure, which is about one unit on a 1 mL syringe and half a unit on a 0.3 mL syringe.
A quick check
Before trusting any result, check that it is plausible: the draw should be smaller than the vial’s total volume, the number of draws per vial should match a rough mental estimate, and changing the water volume should change the units but not the number of draws.
Questions
How can I check my calculator result by hand?
Divide vial mg by mL of water to get mg/mL. Divide the target mg by that to get mL. Multiply by 100 for U-100 units. If your hand result and the calculator disagree, find out why before proceeding.
Why does the calculator warn about draws under 2 units?
Syringe markings and dead space make tiny volumes imprecise. A half-unit error is 25% of a 2-unit draw.