Hard-boiled eggs themselves don’t float because they’re cooked; if an egg floats in water during cooking or before you start, that usually indicates an older egg with a larger internal air cell, not that it’s unfinished or done. The float test is a buoyancy check for freshness, not a doneness indicator. Here’s how to interpret and use this: What float means

• Fresh eggs tend to sink or lay flat on the bottom when placed in water. An egg that tilts with the larger end up or stands on its end is somewhat older, due to a growing air cell inside as moisture and gases move through the shell. A fully floating egg is typically quite old and may be spoiled, though not always unsafe by itself. In any case, float status is about freshness, not doneness.

How to determine doneness reliably

• Use the spin test: after cooking, give the egg a quick spin on a flat surface. A hard-boiled egg spins smoothly; a raw egg wobbles. This helps confirm doneness without cracking.

• The classic method: for hard-boiled eggs, cook for about 9–12 minutes (depending on egg size and altitude); then chill promptly to stop further cooking. If you’re unsure, do a test batch to dial in times for your setup.

• If you’re unsure about safety due to float results before cooking, check for off smells or unusual textures after cracking. An off odor or slimy, greenish yolk can indicate spoilage.

Practical tips

• If an egg floats during the water test before cooking, mark it as older and consider using it for hard-boiled purposes (where freshness matters less than in raw consumption), or discard if it smells off after cracking.

• To ensure reliability, rely on timing and the spin test rather than buoyancy alone when assessing doneness.

Direct answer: Do hard-boiled eggs float when they are done?

• Not as a rule. Hard-boiled eggs are not expected to float because of being cooked; floating during the cooking or freshness test usually signals an older egg with a larger air cell, not doneness. Use the spin test and a timer-based method to confirm doneness, and treat floating eggs as a freshness cue rather than a doneness indicator.