On any inground liner change we come to your house and measure the pool. We want an exact fit on your liner to insure that it fits right. We do not want it to big and end up having wrinkles. We don't want it to small and end up stretching to much. Even if you have the original build specs for your pool, we still measure. Through experience we have come to find that alot of vinyl pools are not built to specs. Even though a liner will "streeetch" into place if the dimensions for the pool bottom are not right, it will shorten the liner life. We want you to get the longest life possible out of your liner, so we measure to insure a perfect fit before we order you a new liner.