Measure side to side (Width) and front to back (Depth) at the shortest distance between the sides.
Please note that if you currently have a multi-piece grate that you’ll be replacing, you should measure the grill rather than the old grate. This is because some combinations of grills with multi-piece grates have “lips” on the sides that the grate pieces slide under before coming together. As MyTeamsGrate grates are a single piece, they can’t typically be slid under lips on both sides, but rather are placed straight down. As such, the one piece grate may need to be slightly shorter than the two or three piece grate.