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Cooking an egg

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The Scientific Egg

Well, I don't know what you expected, but this is really about cooking an egg. (If you've been here before and know what it's about, there is a less verbose similar page!)

Some time ago I read about Werner Gruber, University of Vienna, who had found a formula to create the perfect soft-boiled egg. (More on his homepage, albeit in German.)
We actually do apply the formula at home with good success, but I had an urge to perfect it. That urge was triggered not by a desire for eggs (I hate boiled eggs), but by the annoying ignorance of people:
Twice already (in Zuoz and Flims), our hotel's breakfast buffet featured one of these egg cookers where water is boiling merrily while the guest lowers an egg into it. Usually, an hourglass is provided - together with the note that due to the high elevation (and water boiling at lower temperatures), one is to expect an egg cooking time prolonged by 2 minutes.

Which is nonsense, of course. Yes, if the water doesn't get as hot as in the lowlands, the eggs will need a little more time. But 2 minutes? I guess those "2 minutes" were introduced mainly to amaze the guests about the wonders of the incredible high altitudes in Switzerland. (That said, Flims is on about 1080m, you can well leave the oxygen tanks at home…)

If you play around with the numbers below, you'll find that, under otherwise identical conditions, an egg boiled on 2000m needs about 20 seconds more than its counterpart on sea level, the difference between 500m and 1500m of elevation is a mere 11 seconds.

Will the world now be a better place? I don't think so, but I can but try.

Caveat: In case your life depends on the cooking of your egg, I should advise you that the calculations below suffer from JavaScript's and my own dismal math abilities, so take them (and your egg) with a pinch of salt.

The preset default values below usually make sense, so if you only change the diameter you'll still be ok, sort of.


I'll look up some weather app to find out, usually. You'll find that this value is not overly important for egg cooking purposes.

As stated above, the importance of this is often overestimated. Play around a little bit and see for yourself.

Again, this is often found in your weather app. This is NOT the actual barometric pressure of your location, barometers are not very reliable so I use the official value (which the algorithm then converts to the local barometric pressure).

Please measure where the egg is widest, not longest! If you use a ruler be extra careful, parallax error can be a problem and this measurement is a critical factor. I use a vernier caliper (no joke).

If you take your eggs directly from the fridge, use your fridge's temperature. Note, however, that even my rather small fridge has a temperature difference of 6°C from the lowest to the highest shelf. I use a thermometer, of course.

62°C is where soft-boiled eggs start, the range ends around 82°C with a proper hard-boiled egg. Play around until you're happy.


You local barometer reading should be around please calculate
with the water boiling at please calculate
.

Cooking time for this egg at this location is please calculate.

What about weight?

Yes, I hear you. It's a lot easier to weigh an egg than defining its diameter. A guy called Charles D. H. Williams has taken care of the issue and published his own formula, based on weight of the egg.

Now I am not saying the formula is useless (a simplified version is on German Wikipedia, BTW), but for me it simply does not work. The cooking time (to 62° C) of a 46mm/66g egg is about 30s less in the weight formula than in the diameter formula - but even using the latter, the egg is very soft.
So while I toyed with implementing the formula here, I cannot do so in good conscience.

Last changes: 01.02.2015

© 2015 by Thorsten Heitzmann