Get precise boiling times for soft, medium, or hard boiled eggs. Adjusts for egg size, starting temperature, and altitude for perfect results.
The difference between a perfect soft-boiled egg with a gloriously runny yolk and a chalky, overcooked one comes down to just 60 seconds of cooking time. Boiling eggs seems simple, but getting them exactly right requires precision — the ideal time varies based on your desired doneness, the size of the eggs, whether they started cold from the fridge or at room temperature, and even your altitude above sea level.
At higher altitudes, water boils at a lower temperature, which means eggs take longer to cook. At sea level, water boils at 212°F (100°C), but at 5,000 feet it boils at about 203°F, and at 10,000 feet just 194°F. This temperature difference can add 1-3 minutes to your cooking time. Similarly, an egg straight from the refrigerator (38°F) takes about 1 minute longer than a room-temperature egg (68°F) because it needs extra time to warm up before the cooking process truly begins.
This calculator accounts for all these variables and gives you a precise timer for your perfect egg. Whether you want jammy, runny, creamy, or fully set yolks, you'll nail it every time.
Egg boiling is deceptively tricky — a minute too long ruins the yolk. This calculator adjusts for every variable so you get your preferred doneness perfectly, whether you're at sea level or in the mountains. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain. Use this clarification to avoid ambiguous interpretation.
Boil Time = Base Time × Size Factor × Temperature Factor + Altitude Adjustment. Base times (large egg, room temp, sea level): soft = 6 min, medium-soft = 7 min, medium = 9 min, medium-hard = 11 min, hard = 13 min. Size factors: small = 0.85, medium = 0.92, large = 1.0, XL = 1.1. Fridge start adds 1 min. Altitude adds 1 min per 2,000 ft above sea level.
Result: 12 minutes 30 seconds
Base time for medium is 9 min. Fridge start adds 1 min = 10 min. Altitude adjustment at 5,000 ft adds 2.5 min = 12.5 min total. Lower into already-boiling water and start timer.
When you heat an egg, the proteins in the white begin to denature (unfold) at about 144°F (62°C) and fully set by 180°F (82°C). The yolk proteins set at a higher temperature — around 158°F (70°C) for a just-set yolk and 170°F (77°C) for a fully firm yolk. This temperature gap is why the white sets before the yolk, and why a perfectly timed egg can have a firm white and a runny yolk simultaneously. Overcooking pushes the yolk temperature past 170°F, causing the iron in the yolk to react with sulfur in the white, producing that telltale green ring and a dry, crumbly texture.
**Soft-boiled (6 min):** White barely set, yolk completely liquid. Perfect for dipping toast soldiers. **Medium-soft (7-8 min):** White fully set, yolk jammy around the edges with a liquid center. The "ramen egg" level. **Medium (9-10 min):** White firm, yolk creamy and golden throughout — no liquid, no chalkiness. Ideal for lunch. **Medium-hard (11 min):** Yolk mostly set with a slightly moist center. Great for salads. **Hard (12-13 min):** Yolk completely set, pale yellow, slightly crumbly. Best for deviled eggs and egg salad.
**Eggs crack during cooking:** Bring to a gentle boil (not a vigorous one), start in cold water, or prick the fat end with a pin to release the air pocket. **Yolk is off-center:** The yolk floats to the thinner side. Stir gently in the first 2 minutes to center the yolk for prettier deviled eggs. **Difficult to peel:** Use older eggs, add baking soda or vinegar to the water, and always ice-bath immediately. Steam (vs. boiling) also helps with peeling.
For large eggs at sea level starting from boiling water: 12-13 minutes from the fridge, or 11-12 minutes from room temperature. The yolk will be fully set with no green ring if you ice-bath immediately.
For a soft-boiled egg with a runny yolk, boil for 6-7 minutes (large egg, room temp, sea level). For a jammy/creamy yolk that's set at the edges but gooey in the center, go 7-8 minutes.
Starting in boiling water gives more consistent results because the timing starts from a known temperature. Cold water start is gentler (fewer cracks) but less precise since stove power varies.
The green ring is iron sulfide, caused by overcooking. It's harmless but unappetizing. Prevent it by not exceeding 13 minutes for large eggs and immediately transferring to an ice bath.
Yes! Water boils at lower temperatures at higher altitudes. At 5,000 feet, water boils at ~203°F instead of 212°F, so eggs cook more slowly. Add about 1 minute per 2,000 feet of elevation.
Use eggs that are at least 1 week old (fresher eggs are harder to peel). Add a teaspoon of baking soda to the water. Shock in ice water immediately. Roll gently to crack all over, then peel under running water.