What people use the Bachem calculator for
Bachem is a long-established peptide manufacturer. Its peptide-properties calculator returns molecular weight, extinction coefficient at 280 nm, isoelectric point, and net charge from a pasted amino acid sequence. It is one of the calculators most commonly cited in protein and peptide technical references.
What it does not cover is the practical dosing workflow: turning a lyophilized vial into a measured draw. Concentration from vial amount and water volume, dose volume from a target dose, and syringe-unit conversion all sit outside its scope. PepSync covers that side.
How PepSync and Bachem's calculator compare
A factual feature comparison — both tools have legitimate uses, and they overlap on the peptide-properties side.
| Capability | Bachem | PepSync |
|---|---|---|
| Peptide molecular weight from sequence | Yes | Yes (tool) |
| Extinction coefficient at 280 nm | Yes | Yes |
| Isoelectric point / net charge | Yes | Yes |
| Reconstitution math (mg, mL, mg/mL) | No | Yes |
| Dose volume from target dose | No | Yes |
| Syringe unit conversion (U-100, U-50, U-40) | No | Yes |
| Peptide-specific calculators (semaglutide, BPC-157, etc.) | No | Library |
| Saved protocols + dose reminders | No | iOS app |
| Free, no signup, no ads | Yes | Yes (web) |
When to use which
For peptide-properties analysis on a custom sequence — the kind of math run when characterising a synthesised peptide — either Bachem's calculator or PepSync's molecular weight calculator works. The formulas are standard.
For practical dosing — turning a vial of compounded semaglutide, tirzepatide, BPC-157, or similar into a measured dose with the right syringe units — PepSync covers the workflow Bachem does not. The web tool is free; the iOS app stores the setup so you do not re-derive it every time.