Peptulator

Peptide storage chart

How long a vial lasts as powder and once mixed, in the fridge, the freezer and on the counter, with a discard-by date for the vial in your hand.

Once you add bacteriostatic water, the clock starts. Powder is the stable form; a mixed vial is a solution with a limited fridge life, and nothing about its appearance tells you when it has lost potency. The table is the conservative consensus, the same figures printed in The Protocol Pack. Most of these compounds have never been through a formal stability programme, so treat it as a planning rule, not a guarantee, and use anything you are unsure about sooner rather than later.

How long peptides last, by state and place

StateWhereWorking assumption
Powder, sealedFreezer, -20 °CLongest. Years, per most vendor documentation
Powder, sealedFridge, 2 to 8 °CMonths to years; 12 to 18 months is a sensible working limit
Powder, sealedRoom temperatureWeeks. It ships this way routinely
ReconstitutedFridge, 2 to 8 °C2 to 4 weeks is the conservative window; 3 to 8 weeks is commonly quoted, compound dependent
ReconstitutedRoom temperatureDays at most. Refrigerate as soon as you notice
ReconstitutedFreezerAvoid. Freeze-thaw damages folded peptides
Any stateDirect sun, a hot car, a checked bagAssume degraded
Discard-by date

Date you mixed the vial and the window you work to

Pick the date you added the water.

Write it on the vial in marker. The number is a planning date, not a guarantee: discard earlier if the solution turns cloudy or shows particles.

Why the mixed vial is the weak point

Bacteriostatic water carries 0.9% benzyl alcohol, which holds back bacterial growth across repeated needle entries and is what buys weeks rather than days. It does not stop the peptide itself slowly breaking down in solution. That is why the practical rule is to mix only what you will use in the window above: if a vial would last you five months at your dose, the powder is safer in the fridge than the solution. The reconstitution calculator shows doses per vial, which tells you how long a vial will actually take to finish.

Rules that follow from the table

Travelling with a mixed vial

Hold luggage and car interiors both reach temperatures far outside the useful range, so a vial travels in hand luggage, cold, and never in a checked bag or a glovebox. An insulated pouch with a cool pack covers a day. For longer trips, VialHaus Cold, from the same team as this site, is a battery cooler with a vial tray that holds the 36 to 46 °F fridge range in a normal room; its battery is about 50 Wh, under the 100 Wh airline limit, so it goes in the cabin. VialHaus also makes hard-shell vial cases and a free date tracker for what is in your fridge. It ships in the US only.

Signs a vial is past it

Persistent cloudiness, particles, strands, discolouration, a film on the glass, or a change in smell. Any of those and the answer is the same: discard it. So is a vial whose history you cannot account for. For the longer version, with how to handle a vial that was left out overnight, see the storage guide at Peptide Bureau.

Peptulator, peptulator.com. Research use only, not medical advice.

Free downloadThe Protocol Pack

25 printable pages: dosing cards for the twelve most-used compounds at three water volumes, titration planners, a vial log, and five pages on what to do when it has already gone wrong.

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Common questions

How long does a reconstituted peptide last in the fridge?
Two to four weeks is the conservative working window at 2 to 8 °C with bacteriostatic water. Three to eight weeks is commonly quoted and it depends on the compound, but few research peptides have published stability data, so plan on the short end.
How long does peptide powder last?
Sealed and in the fridge, months to years; 12 to 18 months from receipt is a sensible working limit. Frozen, longer. At room temperature, weeks, which is why powder ships without ice routinely.
Can I freeze a reconstituted peptide?
It is best avoided. Freezing and thawing a solution damages folded peptides, and repeated cycles are worse than one. Mix smaller amounts instead.
Does a vial go bad if it was left out overnight?
One night at normal room temperature is usually not the end of a mixed vial, but it shortens the window. Refrigerate it straight away and use it first. A night in a hot car or in direct sun is different: assume it is degraded.
Does bacteriostatic water make it last longer than sterile water?
Yes. The benzyl alcohol preservative is what makes weeks of repeated use possible. It is what buys three to four weeks of refrigerated life instead of about one with sterile water.

All calculators and charts

Weight management (GLP-1 family)

Growth hormone axis

Repair, skin and blends

Other compounds

Dosage charts and schedules

Tools

Before you use these numbers This is a unit-conversion tool. It turns a vial strength and a water volume into a concentration, a draw volume and a syringe mark. It does not tell you what to take, whether to take it, or whether a compound is safe for you. Most compounds listed are sold for laboratory research and are not approved for human use. Nothing here is medical advice. Dosing decisions belong with a licensed clinician who knows your history. Always check the strength printed on your own vial rather than trusting a preset.