I bought a ateco 11 piece set cookie cutters and they dont have the size on them, does anyone know, it starts 3/4" to 3 5/8". And how convert cm into inches.

Sandy, here's a website where you can make your conversions:

http://www.onlineconversion.com/length_common.htm

Just type in the amount in centimeters or inches, or anything... and then choose FROM (centimeter) TO (inches) or FROM (inches) TO (centimeters) if you want to.

As for the set, maybe they're just graduated cutters and they would go from 3/4" maybe to 1"? Not sure which one you have!

This one?

http://www.amazon.com/dp/B00004S1CI/?tag=cakecentral-20

You might have to calculate or measure the pieces in between. Maybe they go in increments of 1/4"?