Egg Boiling Time Calculator

Background.

This calculator estimates how many minutes to boil an egg for a soft, medium, or hard yolk, adjusted for egg size and altitude. The result is a texture estimate, not a food-safety clearance. FDA guidance for shell eggs is to cook until both the yolk and white are firm. Soft and jammy options are intentionally under that standard; use pasteurized eggs when a recipe or preference calls for undercooked egg, and do not serve undercooked eggs to people at higher risk of severe foodborne illness.

Altitude matters because water does not get as hot at elevation. At sea level, water boils at 212°F. At 5,000 feet, it boils at roughly 203°F because atmospheric pressure is lower. USDA FSIS high-altitude guidance says cooking takes longer and gives an approximate adjustment of one additional minute of boiling time per 1,000 feet above 3,000 feet, which this calculator applies.

Egg size is another variable. The hard-cooked timing chart used here gives medium eggs about 9 minutes, large eggs about 12 minutes, and extra-large eggs about 15 minutes at sea level — ratios of 0.75, 1.00, and 1.25 relative to a large egg. The same ratios are applied to soft and medium preferences because no authoritative table provides every size-doneness combination. Those cells are disclosed estimates, not separate USDA or FDA figures.

Doneness is a spectrum. A soft-boiled egg has a set white and liquid yolk; a jammy egg has a thickened but non-firm yolk; a hard-cooked egg has both white and yolk fully firm. Starting temperature, pot geometry, water volume, and the vigor of the boil can shift the real result, so check texture as well as the clock.

For repeatable texture, use the same starting-water method, pan, water depth, and refrigerator temperature each time, then adjust the next batch by a small amount. Transfer cooked eggs to cold water promptly to stop carryover cooking. A clock result cannot reveal whether the center actually became firm, so the hard-cooked setting should still be checked by appearance when food safety is the reason for choosing it. Anyone preparing eggs for young children, older adults, pregnant people, or people with weakened immune systems should follow the FDA's firm-yolk-and-white guidance rather than relying on a preferred runny texture. Pasteurized shell eggs or pasteurized egg products are the safer choice when a dish is intentionally served raw or undercooked. The calculator does not estimate pasteurization, bacterial contamination, or an individual's medical risk.

What is egg boiling time calculator?

An egg boiling time calculator estimates how many minutes an egg needs in boiling water to reach a chosen doneness — soft, medium, or hard-boiled — accounting for egg size and altitude. It exists because 'boil an egg for N minutes' is a common piece of kitchen folklore that quietly assumes a specific egg size and sea-level atmospheric pressure, both of which vary in the real world.

The calculator starts from a base sea-level time for a large egg (soft 6 min, medium 9 min, hard 12 min), scales that time for smaller or larger eggs using a size ratio anchored to a widely corroborated hard-boil chart, and then adds time for elevation, since water boils at a lower, less effective temperature the higher up you cook. The altitude adjustment follows USDA FSIS's published high-altitude cooking guidance: roughly one added minute of boiling time per 1,000 feet above about 3,000 feet.

How to use this calculator.

1. 01Select your egg size: medium, large, or extra-large.
2. 02Select your target doneness: soft, medium, or hard-boiled.
3. 03Enter your altitude in feet — use 0 if you're not sure and you're near sea level.
4. 04Read the estimated boiling time in minutes.
5. 05Start timing once the water returns to a full rolling boil after the eggs go in.
6. 06For infants, young children, older adults, pregnant people, or anyone immunocompromised, choose hard-boiled — fully firm whites and yolks.

The formula.

The calculator starts with a base time for a large egg at sea level: 6 minutes for soft, 9 minutes for medium, 12 minutes for hard, at a rolling boil. That base time is multiplied by a size ratio — 0.75 for medium eggs, 1.00 for large eggs, 1.25 for extra-large eggs — derived from the widely corroborated hard-boiled-egg chart (medium 9 min / large 12 min / extra-large 15 min, which reduces to exactly those three ratios). For a medium hard-boiled egg, that is 12 × 0.75 = 9.0 minutes; for an extra-large soft-boiled egg, 6 × 1.25 = 7.5 minutes.

The altitude adjustment is added on top, not multiplied in, because it reflects a genuinely different physical effect: water's boiling point itself dropping with elevation, per USDA FSIS's high-altitude cooking guidance of roughly one extra minute of boiling time per 1,000 feet above about 3,000 feet. Below that 3,000-foot threshold, no adjustment is applied. At 6,000 feet, the adjustment is (6000-3000)/1000 x 1 = 3 additional minutes; a large hard-boiled egg that takes 12 minutes at sea level takes about 15 minutes at 6,000 feet.

The calculator also reports an approximate boiling point at the chosen altitude, using the commonly cited linear approximation that water's boiling point drops about 1.8°F for every 1,000 feet of elevation — 212°F at sea level down to roughly 203°F at 5,000 feet, consistent with the physical relationship between atmospheric pressure and boiling point (the Clausius-Clapeyron relationship). This number is shown for context, to make visible WHY altitude changes cooking time, not as a separate adjustment to be applied on top of the minutes already calculated.

A worked example.

Frequently asked questions.

References& sources.

1. [1]U.S. Department of Agriculture, Food Safety and Inspection Service. "High Altitude Cooking." FSIS.
2. [2]Colorado State University Extension. "High Elevation Food Preparation Guide."
3. [3]MedlinePlus, National Library of Medicine, National Institutes of Health. "Perfect Hard-Cooked Eggs."
4. [4]U.S. Food and Drug Administration. "What You Need to Know About Egg Safety." FDA.