Most households throw out eggs the moment they pass the printed date on the carton, wasting perfectly good food and money. Yet food safety experts say that expiration dates on egg cartons are often misunderstood — and that the real signs of a bad egg are simpler, more reliable, and detectable with nothing more than water, your nose, and your eyes. Here is everything you need to know to make the right call every time.
Eggs are one of the most consumed foods on the planet, yet one of the most mishandled when it comes to freshness and safety. Each year, millions of perfectly edible eggs end up in the trash because consumers confuse “best by” dates with actual spoilage — while on the other end of the spectrum, genuinely bad eggs are cracked open and consumed without a second thought. Understanding the difference could save you money, reduce food waste, and — most importantly — protect your health.
The Main Facts: What Actually Tells You an Egg Has Gone Bad
The Sniff Test: Most Reliable of All
The single most dependable method for detecting a spoiled egg is simply smelling it. A bad egg produces a sulfurous, unmistakably foul odor caused by hydrogen sulfide — a gas that forms as the egg’s proteins break down over time. This smell is present whether the egg is raw or cooked, and in very old or severely rotten eggs, it can sometimes be detected even through the shell before cracking it open. If anything smells off, the answer is simple: throw it out.
The Float Test: What It Actually Measures
The float test is popular and widely shared, but it is often misunderstood. The science behind it is straightforward — as an egg ages, moisture and carbon dioxide escape through the shell’s tiny pores, and a growing air pocket forms inside. A fresh egg sinks flat to the bottom of a bowl of water, an older-but-still-safe egg tilts slightly upward, and an egg that floats entirely to the surface has a significantly large air cell and should be discarded. However, food safety experts caution that floating indicates age and density — not necessarily bacterial contamination. An egg can float and be safe, or it can sink and be dangerous if it carries internal bacteria. That is why the float test should never be used in isolation.
Visual Inspection: Before and After Cracking
Before you even crack an egg, check the shell. Cracked, slimy, or powdery shells are signs that bacteria may have penetrated the egg. Once cracked onto a clean white plate or bowl, look carefully at the yolk and whites. Fresh eggs have a firm, rounded, domed yolk that sits high — a flat, watery yolk indicates age. Pink, iridescent, or greenish discoloration in the whites or yolk signals bacterial growth and means the egg should be immediately discarded.
Expiration Dates: What They Actually Mean
The printed dates on egg cartons are frequently misread as hard safety deadlines, but they are not. According to the USDA, raw eggs in their shells can be safely consumed three to five weeks after purchase when stored properly in a refrigerator at or below 40°F (4°C). The Egg Safety Center goes further, stating eggs may remain safe up to five weeks past their carton packing date with correct refrigeration. The Julian date — a three-digit number found on the short side of most cartons representing the day of the year the eggs were packed — is a more precise freshness reference than the “sell by” label.
The stakes here extend beyond food waste. Eggs are one of the primary vehicles for Salmonella, a bacterium responsible for tens of thousands of foodborne illness cases globally each year. Symptoms — including stomach cramps, diarrhea, nausea, vomiting, chills, and fever — typically appear within 6 to 72 hours of consuming contaminated food. In 2025 alone, the U.S. Food and Drug Administration issued multiple Salmonella-related egg recalls, including one involving an Arkansas-based egg producer where 40 environmental samples at the processing facility tested positive for the bacterium.
Critically, Salmonella does not always make an egg look or smell bad. This is what makes proper handling and cooking so essential. The FDA consistently advises that eggs be cooked to an internal temperature of 160°F (71°C) — typically when the yolk becomes firm — to eliminate any bacterial risk. People with compromised immune systems, the elderly, pregnant women, and young children face the greatest danger and should never consume raw or undercooked eggs.
Storage also plays a major role in how long eggs remain safe. Unlike much of Europe, where eggs are unwashed and stored at room temperature, U.S. eggs are washed during processing, removing their natural protective coating called the “bloom” or cuticle. This makes refrigeration non-negotiable for commercially sold eggs in the United States. Hard-boiled eggs, by contrast, have a much shorter shelf life — up to one week in the refrigerator — because the cooking process also removes the shell’s protective barrier.
What emerges from the science and the expert consensus is a straightforward message that, surprisingly, most consumers still don’t know: printed dates are not expiration dates, the float test is not a safety test, and the nose remains the most trustworthy instrument in the kitchen. The widespread confusion around egg freshness is not just a minor inconvenience — it drives unnecessary food waste on a massive scale while simultaneously failing to protect people from the eggs that genuinely pose a health risk.
The solution is low-cost and easy: check the shell, do the float test as a first filter, crack the egg onto a clean plate and use your senses, and always cook eggs thoroughly. When in genuine doubt, the FDA’s position is clear and sensible — throw it out. A few cents saved on a questionable egg is never worth the risk of a severe foodborne illness.
