Egg Boiling Calculator
Calculate the perfect boiling time for eggs based on size, desired doneness, starting temperature, and altitude. Get precise timing for soft-boiled, medium, or hard-boiled eggs every time. See also our Cooking Converter and Turkey Cooking Time Calculator.
How to Boil Eggs Perfectly
Boiling eggs seems simple, but achieving your desired doneness consistently requires attention to several variables: egg size, starting temperature, altitude, and the number of eggs in the pot. This calculator accounts for all these factors to give you a precise boiling time that produces perfect results every time.
The method is straightforward: bring a pot of water to a full rolling boil, then gently lower your eggs into the water using a slotted spoon or spider strainer. Start your timer immediately. When the time is up, transfer the eggs to an ice bath (a bowl of ice water) to stop the cooking process. This method — starting with boiling water rather than cold — gives you more precise control over timing because the starting point is consistent.
Select your egg size, desired doneness (soft-boiled with a runny yolk, medium with a jammy center, or hard-boiled with a fully set yolk), whether your eggs are starting from room temperature or the refrigerator, your altitude, and how many eggs you are cooking. The calculator adjusts the time for each variable to give you the optimal result.
Egg Boiling Time Formula
Total Time = Base Time + Size Adj. + Temp Adj. + Altitude Adj. + Quantity Adj.
Base Times (large, room temp, sea level):
Soft-boiled: 6 minutes
Medium: 9 minutes
Hard-boiled: 12 minutes
Size: Small (-1 min), Medium (-0.5), Large (0), XL (+1)
Starting Temp: Room (0), Fridge (+1 min)
Altitude: Sea level (0), High 5000ft+ (+2 min)
Quantity: +0.5 min per egg over 4
The base times assume large eggs at room temperature at sea level, lowered into already-boiling water. Each adjustment factor accounts for the physics of heat transfer: larger eggs have more mass to heat through, cold eggs absorb more heat energy from the water initially, high altitude lowers the boiling point of water (reducing the temperature differential), and more eggs in the pot temporarily lower the water temperature.
Example Calculation
Let us calculate the boiling time for 6 large eggs from the fridge, hard-boiled, at sea level:
Step 1: Base time for hard-boiled = 12 minutes
Step 2: Size adjustment (large) = 0 minutes
Step 3: Starting temp (fridge) = +1 minute
Step 4: Altitude (sea level) = +0 minutes
Step 5: Quantity adjustment (6 eggs, 2 over 4) = +1 minute
Step 6: Total = 12 + 0 + 1 + 0 + 1 = 14 minutes
Result: Boil for 14 minutes, then transfer to ice bath for 10 minutes. The yolk will be fully set with no green ring.
Egg Boiling Time Reference Table
| Doneness | Small | Medium | Large | Extra-Large | Yolk Description |
|---|---|---|---|---|---|
| Soft-Boiled | 5 min | 5.5 min | 6 min | 7 min | Completely runny, liquid center |
| Medium-Soft | 6 min | 6.5 min | 7 min | 8 min | Mostly runny with slightly set edges |
| Medium | 7 min | 8.5 min | 9 min | 10 min | Jammy, gooey center, set edges |
| Medium-Hard | 9 min | 9.5 min | 10 min | 11 min | Mostly set with slightly soft center |
| Hard-Boiled | 11 min | 11.5 min | 12 min | 13 min | Fully set, pale yellow throughout |
| Very Hard | 13 min | 13.5 min | 14 min | 15 min | Fully set, may develop green ring |
Times shown are for room-temperature eggs at sea level, lowered into boiling water. Add 1 minute for fridge-cold eggs and 2 minutes for high altitude (5,000+ feet). The "very hard" category is included as a warning — cooking beyond 14 minutes for large eggs risks developing the unappetizing green-gray ring around the yolk caused by iron sulfide formation.
The Science of Boiling Eggs
Egg whites begin to set at 144°F (62°C) and are fully firm at 180°F (82°C). Egg yolks begin to thicken at 149°F (65°C) and are fully set at 158°F (70°C). The challenge of boiling eggs is that the heat must travel from the outside in, meaning the white is always hotter than the yolk. This temperature gradient is what allows us to achieve different doneness levels — by controlling time, we control how much heat reaches the center.
The green ring that sometimes forms around hard-boiled yolks is iron sulfide, created when hydrogen sulfide from the white reacts with iron in the yolk at high temperatures. It is harmless but unappealing. To prevent it, avoid overcooking and cool eggs quickly in an ice bath. The ice bath stops the residual heat from continuing to cook the egg after removal from the water.
At high altitude, water boils at a lower temperature (approximately 202°F/94°C at 5,000 feet versus 212°F/100°C at sea level). This lower temperature means less heat energy is transferred to the egg per unit of time, requiring longer cooking. For every 1,000 feet above sea level, add approximately 20-30 seconds to your boiling time. At 7,500 feet, you may need to add 3-4 minutes to standard sea-level times.
Tips for Easy-Peel Eggs
The most frustrating part of boiled eggs is often the peeling. Fresh eggs are notoriously difficult to peel because the egg white bonds tightly to the inner membrane. Here are proven techniques for easier peeling: Use eggs that are 7-10 days old (the pH increases as eggs age, weakening the bond between white and membrane). Add 1/2 teaspoon of baking soda to the boiling water to raise the pH artificially. Start with boiling water rather than cold (the rapid temperature change helps separate the membrane). Use an ice bath immediately after cooking.
When peeling, crack the egg gently on a flat surface and roll it to create a network of small cracks. Start peeling from the wider end where the air pocket is located — there is usually a small gap between the membrane and the white at this end. Peel under cold running water, which helps lift the membrane away from the white. For batch peeling, some cooks place cooled eggs in a container with a small amount of water, cover, and shake vigorously — the shells crack and partially separate.
Frequently Asked Questions
Should I start eggs in cold water or boiling water?
Starting in boiling water gives more precise and repeatable results because the starting point is consistent. Cold-start methods work but timing varies based on pot size, water volume, and stove power. With the boiling-water method, you know exactly when cooking begins.
Why do my hard-boiled eggs have a green ring around the yolk?
The green-gray ring is iron sulfide, formed when eggs are overcooked or not cooled quickly enough. To prevent it, do not exceed 12-13 minutes for large eggs and immediately transfer to an ice bath after cooking. The ring is harmless but indicates overcooking.
How do I make soft-boiled eggs for ramen?
For ramen-style eggs (ajitsuke tamago), boil large eggs from the fridge for 6.5-7 minutes for a jammy yolk. Ice bath for 5 minutes, peel carefully, then marinate in a mixture of soy sauce, mirin, and water for 4-12 hours in the refrigerator. The longer the marinade, the deeper the flavor penetrates.
Can I boil eggs in the microwave?
It is not recommended. Eggs can explode in the microwave due to steam pressure building inside the shell. If you must use a microwave, use a microwave-safe egg cooker designed for this purpose, which controls the heating rate. Stovetop boiling is safer and produces more consistent results.
How long do boiled eggs last in the refrigerator?
Hard-boiled eggs in their shell last up to 7 days in the refrigerator. Peeled eggs should be eaten within 2-3 days and stored in a covered container (they can absorb odors). Soft and medium-boiled eggs should be eaten within 2 days as the runny yolk is more perishable.
Does adding salt or vinegar to the water help?
Adding salt raises the boiling point slightly (negligible effect on cooking time) but can help seal cracks if an egg breaks during cooking. Vinegar (1 tablespoon per quart) helps the white coagulate faster if the shell cracks, preventing large streamers. Neither significantly affects peeling ease — baking soda is more effective for that.