How to Choose and Store Oysters: Size, Freshness & Tips

I know choosing the right oysters can feel a bit intimidating at first! Between the different sizes, origins, and storage rules, it’s easy to get lost. But don’t worry, here’s everything you need to know to choose the right oysters and keep them perfectly fresh at home.

How to Choose Oysters

There are two main things to pay attention to: the size and the origin. Here, we’ll focus mostly on French oysters but keep in mind there are amazing ones from other regions too! (I’ve tried some from Portugal and Japan… let’s just say, Japan’s weren’t my favorites 😄).

Oyster Sizes

Oysters are graded by number: from No. 5 (the smallest) to No. 0 (the largest).

• No. 4 or 5: small and delicate, perfect for appetizers or a seafood platter.
• No. 3: the classic size (and my favorite !), ideal as a starter or main meal. This is the one I recommend for beginners.
• No. 2: a bit meatier, great if you like a generous, juicy oyster.
• No. 1 and 0: the big ones, often used for cooked recipes like baked or grilled oysters.

The Two Main Types

There are two main types of oysters you’ll come across:

• Crinkled (deep-cupped) oysters: the most common kind (like Fine de Claire, Spéciale de Claire, Tsarskaya).
• Flat oysters: rarer and prized for their strong, briny flavor (such as Belon or Cancale).

French Oyster Regions

If you ever get the chance to try oysters from different French regions, you’ll notice the flavor truly changes depending on where they come from:

• Marennes-Oléron: balanced between sweet and salty, often finished in “claires” (shallow basins). These are the most classic and often my favorite!
• Northern Brittany (Cancale, Paimpol): very briny and intensely ocean-flavored, perfect if you love the sea.
• Normandy: plump and bold, with a deep marine taste.
• Arcachon Bay: dense, meaty texture and full-bodied flavor.
• Mediterranean (Bouzigues, Étang de Thau): milder and rounder, with soft flesh and hints of hazelnut. Still briny, but more gently so.

How to Store Oysters at Home

Oysters are alive: they breathe and need both humidity and cool air. If they’re sealed too tightly or left somewhere warm, they’ll die quickly and become unsafe to eat.

Storage Time & Temperature

• Oysters will keep up to 7 days after harvesting, but I recommend buying them 1 to 2 days before serving, or even the same day if possible.
• Temperature: store them between 41°F and 50°F (5–10°C). The best spot is the crisper drawer in your fridge, or a cool place like a garage or balcony if the temperature stays under 50°F.

How to Store Them Properly

1. Keep them in their original wooden box (the “bourriche”), lid closed. Be careful! Remove any plastic wrapping, oysters need to breathe.
2. Cover them with a slightly damp towel, never soaking wet.
3. Avoid placing them directly on ice. Too much cold can “shock” and kill them.
4. If you’re using ice for transport, place it around the box, never underneath or in direct contact with the shells.

How to Spot a Dead or Unsafe Oyster

Dead oysters are the only real danger, they can contain harmful bacteria, so if in doubt, toss them out.

Before opening

• If the shell is slightly open and doesn’t close when tapped, throw it away.
• If it feels hollow or unusually light, it’s probably empty.
• If it smells sour or strong, definitely not safe to eat.

After opening

• It should smell clean and ocean-fresh.
• The flesh should look shiny, firm, and sitting in a bit of clear, salty water.
• If it looks dry, dull, or doesn’t release a bit of liquid after a few minutes, discard it.
  
  

👉 If you’re not sure how to open oysters safely, check out my full tutorial: How to Open Oysters. You’ll also find my tips for serving them beautifully in How to Serve Oysters Like a Pro.

Frequently asked questions