The Big Green Egg is equipped with a dome thermometer that all of us Eggheads use as a guide for how long we cook our food. But, how do you really know that what the thermometer says is true? Are you cooking those ribs at 250F like you think, or is it more like 300F? A faulty dome temperature reading can be the difference between grilling something delicious and something inedible. And if you don’t own a Polder Probe, your reliance on the Big Green Egg dome thermometer is all the greater. Read on to learn about calibrating the Big Green Egg dome thermometer to be sure it’s reading the correct temperature.

Remove the Dome Thermometer:
Carefully remove the dome thermometer from the Big Green Egg by simply pulling it out. There is a metal clip on the inside of the dome that will fall, so set something inside your grill to catch it.

Boil a Pot of Water:
If you remember high school physics, water boils at 212F or 100C. We can use this fact to calibrate the Big Green Egg dome thermometer. Boil a pot of water and carefully balance the thermometer in the boiling water, making sure the tip doesn’t touch the bottom of the pot. To do this, I had to place 2 skewers across the pot to act as stand for the thermometer. Read the thermometer while it’s in the boiling water; if it says 100C (there’s a mark on the thermometer at 100C) then you’re all set. If not, read on.

Adjust the Thermometer Reading:
Use a 7/16″ wrench to turn the nut on the back of the thermometer and adjust the reading. Place the thermometer back in the boiling water to check that it reads correctly. Keep adjusting until it reads right at 100C. When adjusting the thermometer with the wrench, clockwise turns make the thermometer read higher and counter-clockwise turns make the thermometer read lower (when looking at the front of the thermometer). Basically, you turn the nut in the direction you want the needle to move. Only slight adjustments with the wrench are necessary. I’m not talking full wrench turns; more like barely moving the nut. Play around adjusting the thermometer reading to get the hang of it.

Replace the Dome Thermometer:
Using the metal clip, re-install the properly calibrated dome thermometer in your grill. Now you can rest assured that your Big Green Egg is accurately reading the dome temperature.

I also used this opportunity to check that my Polder Probe was reading accurately. Wouldn’t you know it, those guys at Polder do some nice work. 212F on the dot!

Thank you to the many readers that have reminded me that the boiling point of water changes with elevation! So, if you live at elevation and still want to calibrate your BGE Dome Thermometer, here are some charts that show the boiling point of water at various elevations.