Measure to the nearest 1/8 inch. When in doubt, round DOWN.
If the tile is to be inset, measure the INSIDE of the area. Extra space is always preferable to not enough. Vintage or reclaimed items may have paint buildup or some other discrepancies in the corners so you want to account for this.
Try to measure twice in both directions - meaning measure from both ends to make sure the area is square.
If things are wonky like the example below, choose the smaller set of measurements. You’ll have grout around the edges anyway and a slightly larger gap on one side won’t be noticeable.
For more complicated dimensions, such as a backsplash, double check that the top & bottom measurements are equal, as well as the left & right sides. For example: the top & bottom both equal 100”, the sides both equal 30”.
If you realize you’ve made a mistake or something is complicated, don’t worry. Once you send us your measurements, we’ll send you a drawing to confirm before any production starts. And you can always email us any questions.