Egg cartons are full of numbers and codes that aren’t just random—they tell you about safety, freshness, and origin. Ignoring them can put you at risk of foodborne illness, like Salmonella. Here’s what those numbers mean and why they matter:
1. The Expiration Date / “Best By”
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Often labeled as “Sell By,” “Use By,” or “Best Before.”
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Eggs can usually last 3–5 weeks past the pack date if refrigerated properly.
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Why it matters: eating eggs past their safe window increases risk of bacterial growth, especially Salmonella.
2. Pack Date (Julian Date)
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Found as a three-digit number (001–365) on the carton.
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Example: 032 = 32nd day of the year (Feb 1 in a non-leap year)
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Eggs must be sold within 30 days of packing.
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Eggs can remain safe 4–5 weeks after packing if refrigerated.
3. USDA Grade (AA, A, B)
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Grade AA = very fresh, thick whites, yolks round and firm
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Grade A = good quality, most commonly sold in stores
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Grade B = used for baking and processed foods
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Why it matters: lower grades may have weaker shells, increasing contamination risk.
4. USDA Plant Number / Code
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Found as “P-12345” or similar
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Identifies the facility that processed the eggs
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Useful in recalls if eggs are contaminated
5. Expiration vs. Freshness Test
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Float Test:
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Fill a bowl with water
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Fresh eggs sink, older eggs stand upright, bad eggs float
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This is a backup check if you’re unsure of carton numbers.
6. Refrigeration & Handling
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Eggs should be kept at ≤40°F (4°C)
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Don’t leave them out longer than 2 hours
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Cracked eggs = throw away (bacteria can enter easily)
Why Ignoring These Numbers Could Make You Sick
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Eating eggs too old or stored improperly can cause Salmonella infection
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Symptoms: nausea, diarrhea, abdominal cramps, fever (usually 6–72 hours after ingestion)
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Vulnerable groups: young children, elderly, pregnant women, immunocompromised
Quick Tip
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Buy eggs closer to the pack date, not the “use by” date if possible
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Store in original carton in main fridge, not the door
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Cook until yolks and whites are firm
If you want, I can make a quick visual cheat sheet of every number on an egg carton—easy to memorize so you never eat a risky egg again.