Yep - you do have to check with a tape measure before leaving and always hand them a piece of paper with the measurements, make them write it down and keep an eye on their piece of paper as well as pocketing yours! A staff member will always lend you a tape measure. I've had the above experience more than once and am now extra cautious! If you require very accurate measurements and you're calculating out how many lengths you can get from a sheet, it's worth remembering the saw itself takes a few mm off each cut. I can't remember how many???