How to Use This Calculator
Pick the peptide’s stability class (Stable (robust), Standard or Sensitive (labile)), the storage temperature (Refrigerator (2-8 °C), Room temperature (15-25 °C) or Freezer (-20 °C)), the days since you mixed it and how many times it has been frozen and thawed. Click Estimate Stability to see the estimated potency left, a grade (excellent, good, degraded or discard recommended) and the usual storage window for that class.
Why the Same Vial Ages Differently Depending on Storage
Most reconstituted peptides degrade fastest at room temperature, more slowly under refrigeration, and slowest when kept frozen and left undisturbed. Freeze-thaw cycles matter separately from temperature, each cycle stresses the peptide structure a bit further regardless of how cold the vial gets between cycles, which is why a vial frozen and thawed repeatedly can degrade faster than one kept consistently refrigerated. A single flat shelf-life number can’t capture that, since it depends on how the specific vial was actually handled.
Potency Left Over Time (Standard Class, Refrigerated)
The table uses the standard class at 2 to 8 °C, which has a 40-day half-life in this estimator, with no freeze-thaw cycles. These are simplified estimates, not measured data for any specific peptide.
| Days since mixing | Potency left |
|---|---|
| 7 | 88.6% |
| 14 | 78.5% |
| 28 | 61.6% |
| 40 | 50.0% |
| 56 | 37.9% |
Protecting a Vial from the Start
Storage conditions matter less if the concentration was already off. The BAC Water Calculator sets that up correctly at reconstitution, and for a vial nearing the end of a cycle, the Peptide Vial Yield Calculator shows exactly how many doses are left before storage duration becomes a bigger concern than supply.
Who Should Use This
Researchers deciding whether a stored vial is still usable; lab staff comparing storage options for reconstituted peptides.
What This Calculator Does
The Peptide Stability and Storage Estimator gives a rough potency estimate for a reconstituted peptide based on its stability class, storage temperature, days since mixing and freeze-thaw cycles, together with a typical use window for that storage condition.
Formula Used
Potency after storage (%) = 100 × e^(−ln 2 × Days ÷ Class half-life)Final potency (%) = Potency after storage × (1 − Freeze-thaw loss) ^ CyclesClass half-lives range from 1.5 days (sensitive, room temperature) to 365 days (stable, frozen); freeze-thaw loss is 5%, 8% or 12% per cycle by class.
Example Calculation
Limitations
The class half-lives are simplified estimates, not measured data for any specific peptide or formulation. Real stability depends on sequence, concentration, pH, light and container. Follow supplier storage guidance where it exists.
Frequently Asked Questions
How long do reconstituted peptides last in the fridge?
It depends on the peptide and the supplier's storage guidance. This estimator uses simplified class half-lives. For example, a standard-class peptide at 2 to 8 °C has a 40-day half-life, so it keeps about 78.5% potency after 14 days. Follow the supplier's instructions where they exist.
How do I calculate peptide storage potency?
Divide the days stored by the class half-life, multiply by 0.693, and compute 100 x e^(-that number). Then multiply by (1 minus the freeze-thaw loss) for each freeze-thaw cycle. The calculator does both steps for you.
Do reconstituted peptides need to be refrigerated?
Storage temperature changes how fast potency drops. In this estimator, room temperature gives the shortest half-lives (as short as 1.5 days for sensitive peptides), refrigeration gives longer ones and the freezer the longest. Check the supplier's storage guidance for your product.