Older eggs are easier to peel because the egg white shrinks, leaving more space between the shell and the egg. Choosing eggs between 1-2 weeks old is ideal for hard boiled eggs. The cooking times listed are for large eggs, therefore cooking times will vary for eggs that are smaller or larger.
The age of the egg affects how easily the shell will peel away after cooking. Eggs that are too fresh will have difficult shells to remove without damaging the egg white. It is best to use eggs that are at least 7 to 10 days old, allowing the egg to take in air which helps separate the membrane from shell.
 If more than 23 days remain from the current date to the “sell-by” date on the carton, then they are considered very fresh eggs and therefore not good candidates for boiling. It is best to wait until the eggs are at least a week old before using them for the purpose of making hard boiled eggs.
The size, temperature, and age of eggs all affect how easy they peel after hard boiling. For the best results, we recommend using large eggs straight from the fridge that are a week or two old.
With their gorgeous, orange yolks and rich flavor, there aren't many downfalls to farm-fresh eggs. However, since the inner membrane clings tightly to the shell of a fresh egg, it's near-impossible to have anything but ugly results when you try to hard-boil them.
According to our friends at Delish, adding a teaspoon of baking soda to your boiling pot of water will help the shell peel off seamlessly. Why? The alkaline in the baking soda will help your egg whites loosen up from the shell, making it easier to peel.
A boiling start for 30 seconds to a very gentle simmer for 13 minutes, then an ice bath at the end makes perfect, easy-to-peel hard-boiled eggs.
"Get them onto a spoon and drop them into the water", Gordon said, timing six minutes to boil the eggs. "Bring that [the water] to the boil, but don't water them ferociously, or you'll get a black line around the outside, boil them gently."
Soft-boiled eggs: For soft, runny yolks, you want to make sure to remove the eggs at 4 minutes. Medium-boiled yolks: Often described as “jammy”, this is where my preference is, right around 6-7 minutes. Hard-boiled eggs: The range for hard-boiled yolks is anywhere from 8 to 12 minutes.
As soon as the water starts boiling, reduce the heat to medium and boil for one minute. After one minute, cover the pot with a lid and remove from the heat. Then, let the eggs sit, covered, for ten minutes.
To conduct a sink test, fill a bowl or cup with water and ensure it is big enough to submerge the egg entirely. Gently place the egg inside to see whether it sinks or floats. If it sinks, then it's likely safe enough to eat. If it floats, however, it's old, and you'll want to discard it.
So if you crack 'em open after the date has passed, you may notice they don't taste as good, but you're not at risk of illness. In short, you can eat eggs two months out of date. It'll be fine.
The vinegar in the water makes the eggs easier to peel. Here's why: The vinegar's acid not only dissolves some of the calcium carbonate in the shell, it also helps the whites set faster. Running the hard-boiled eggs under cold running water as you're peeling, meanwhile, helps the shell separate from the membrane.
1. Start with old eggs. Farm-fresh eggs will be harder to peel—it's a matter of their particular chemistry. To minimize frustration, save those straight-from-the-hen eggs for poaching or frying and use a carton of slightly older eggs, like the ones from the grocery store, when boiling.
How To Boil Eggs Perfectly: Place eggs in a single layer at the bottom of a large saucepan or pot. Add enough water to cover the eggs with at least 1 in (2.5 cm) of water over them. Add a tablespoon (15 mL) of vinegar and a tablespoon (14 g) of sea salt to the pot.
First, remove your eggs from the fridge about 10 minutes prior to boiling them, if possible, to allow them to warm up a bit.
As soon as the water boils, remove the pot from the heat, cover, and let the eggs sit for 15 minutes (13 minutes for small eggs or 17 minutes extra large eggs). Prepare a bowl of ice water. After 15 minutes, place the eggs in the ice water and allow them to cool completely (about 15 minutes).
Kenji López-Alt's James Beard Award–winning The Food Lab suggests (after many, many rounds of tests) lowering eggs into boiling water for 30 seconds, then adding ice cubes, reducing to a sub-simmer, and cooking for 11 more minutes.
You might have heard that you should drop your eggs into room temperature or cold water and then bring the water to a boil. This is a myth. In our tests, bringing the water to a boil first and then lowering the eggs into the bath made for easy peeling and more accurate timing.
Carefully place the eggs in a large saucepan; add cold water to cover by one inch, and bring to a rolling boil. Cover pan; remove from heat. Let stand 12 minutes, then drain and rinse under cool water. To store, keep eggs unpeeled in the refrigerator, up to 4 days.
Shocking your recently boiled eggs by submerging them into a bowl of ice water is key. The quick cooling of the hard-boiled eggs causes the egg whites to contract, freeing them from the membrane. If you let them cool for about 15 minutes, the peeling is much easier.
Egg white solidifies more quickly in hot, salty water than it does in fresh. So a little salt in your water can minimize the mess if your egg springs a leak while cooking. The egg white solidifies when it hits the salt water, sealing up the crack so that the egg doesn't shoot out a streamer of white.