How to Read Batch Codes and Expiration Labels

So you’ve found a dreamy moisturizer or the perfect secondhand serum at a fraction of the price — yay, we love a good rehome! But before you slather it on, here’s a little trick every beauty lover should know: check the batch code and expiration date.

If you’ve never done this before, don’t worry — you’re definitely not alone. Most of us skip right over those tiny printed codes and embossed numbers. But when shopping secondhand or even digging through your own stash, understanding these little labels can save your skin (literally).

Let’s break it down.

🧾 What’s a Batch Code, Anyway?

A batch code is a short series of numbers, letters, or both printed somewhere on the product packaging — usually on the bottom, side, or crimp of a tube. It’s how brands keep track of production batches, and it tells you when the product was manufactured.

It’s not the same as an expiration date, but knowing when your product was made can help you figure out how much life it has left.

🕵️‍♀️ How to Decode It

Every brand does batch codes differently (annoying, we know). But most use a format that includes:

• The year (e.g., “2” for 2022 or “K” for 2020 depending on brand)

• The day or week of production

• Sometimes the plant or location where it was made

The good news? You don’t need to memorize every brand’s system. There are free online tools like CheckFresh.com or Cosmetic Calculator where you can plug in the code and see the manufacturing date. Bookmark them — they’re total game changers.

⏳ Expiration Labels: What to Look For

There are two types of “expiry” dates in beauty:

1. The Period After Opening (PAO) — This is the little jar icon on the label that says something like 6M or 12M, which means the product is good for 6 or 12 months after opening. It’s an estimate based on when the product is exposed to air, not when it was made.

2. Hard Expiration Dates — Some skincare and sunscreen products (especially if they contain active ingredients like retinol, SPF, or vitamin C) will include a specific expiration date. That’s your cue to toss if it’s expired — even if it’s unopened.

💡 When You're Shopping Secondhand…

Here’s what we recommend before rehoming a product:

• Look for the batch code and run it through a calculator.

• Check the PAO label and ask if the product’s ever been opened.

• Do a smell/texture check when you receive it — if something seems off, it probably is.

• When in doubt? Don’t put it on your face (especially if it’s an active or water-based product).

A Little Shelf Life Cheat Sheet

Product Type	Typical Shelf Life (Unopened)
Powders	2–3 years
Lipsticks	1–2 years
Creams/Liquids	1–2 years
Sunscreen/SPF	Check label — strict expiry!
Natural/Clean Beauty	Often <1 year

💬 Bottom Line?

Just because something’s secondhand doesn’t mean it should be a mystery. Reading batch codes and knowing what those little labels mean is one of the best ways to shop secondhand beauty smartly. At Glou, we’re all about rehoming beauty responsibly — so you can feel good about your choices and your skin.

Got questions about a specific brand’s code? Drop us a comment — we’re happy to help decode!

Smarter beauty starts here — and this is just the beginning of our Beauty Resale series. Stay tuned for more insider tips.

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Why You Should Trust Us

At Glou Beauty, we've spent years immersed in the beauty resale space — building the first purpose-built marketplace for secondhand beauty, gathering real-world data, and working closely with buyers and sellers. Our insights aren’t just theory — they’re informed by lived experience, interviews, and behind-the-scenes knowledge from every corner of the industry. We know what works, what doesn’t, and what’s worth your time (and money). Whether you're here to rehome your stash or shop smartly, you can trust that every Glou guide is grounded in honesty, expertise, and a deep love for beauty — minus the waste.