Figuring in the length plus the coved height, add another 6 or so to each cut. It is a measurement from a plan, so hopefully the plans are correct.... but that's why I would add extra. If it's a large job you need to add on material so they have some for repairs. I would make note of that extra amount so they know you figured extra.Wouldn’t it be 1’3” added to each cut? 6 in. high cove.