Endotracheal Tube Insertion Depth 

Forget those tricky formulae for uncuffed ETT insertion depth. They are too hard to remember.

Instead, put a size 3mm ETT 3cm at the cords. A size 4 ETT goes 4cm at the cords, etc… The trick is that you need to look at the tube first and follow it down with your eyes as you insert it through the cords, as it´s often hard to see the markings once the tube is in place. If your tube does not have cm markings, measure and draw one in the right spot with a felt-tipped pen first.

Next make sure you note what the distance is at the teeth or the lip so you know if your tube has moved. If you have a cuffed tube, insert so that the cuff is just beyond the cords.