How the egg timer works
The timer starts from a baseline for large eggs and then adjusts for three practical variables: egg size, whether the eggs go in fridge-cold or closer to room temperature, and how much altitude lowers the temperature at which water boils.
Instead of outputting just one number, the calculator also keeps the parallel timing sheet visible. That is useful when you are deciding between a jammy centre and a fully set yolk, or when you want to compare how much extra time altitude adds.
Boil time = Base doneness time + size adjustment + start-temperature adjustment + altitude adjustment
Combines the main kitchen factors that shift how long the centre of the egg needs in boiling water.
Boiling point decreases as altitude rises
Higher altitude lowers the temperature of boiling water, so the eggs cook more slowly even when the water is visibly boiling.