Welcome to the Quilting Board!

I feel your pain. As part of Europe we switched to metric, although I was taught in Imperial. All weights and measures are sold by the kilo and metre.
Luckily most quilt patterns are in inches (although we have to buy our fabric by the metre)
2.5 cm and 25mm are the same length - 1".
cm or centimetre is 1/10th of a metre. mm is millimetre, a thousandth of a metre.
A metre is 39" long.
Virtually all our tape measures are two-sided. All I do is flip mine over. If you need me to send you one, pm me.
Lang may yer lum reek. (I'm a knitter - hence - 'Knit-ette'. Confuses a lot of people!)
Maybe this will help with the thinking process:
If one compared a meter to a ten dollar bill (Think ONE THOUSAND PENNIES)
One meter (39.37 inches) = 1000 pennies
One centimeter = 10 pennies (1/100 of the meter - think perCENT or CENTS in a dollar)
One millimeter = 1 penny (1/1000 of a meter - or 1/10 of a centimeter)
The simpler way of doing it is to just get a ruler, measuring stick, or tape measure with both units on it and measure using the guide.
The approximate equivalents are:
One meter - one yard plus 3-1/2 inches
One centimeter - a couple of threads more than 3/8 of an inch
6 millimeters - about 1/4 inch
2/3 of a centimeter - about 1/4 inch
Dreamer, You can check your measuring tape...the other side should be metric.
I taped an old measuring tape onto my ruler so I didn't have to switch back and forth. Worked just fine for the project.
Tink's Mom (My name is really Susie)
now you've been told already what the measurements mean.
But with us here in the netherlands ofcourse it's the other way around.
Because it's almost impossible to do the math and get it 100% right I think indeed the best advise is to get a metric ruler.
I'm working with inch-rulers all the time when I'm quilting
greetz, fien
http://quiltfien.blogspot.com/
GrannieAnnie, none of my quilting rulers have metric. That would be very confusing, since there's enough markings on them already. Where are you finding ones that do? (Not that I need or want them, just wondering.)
That's strange. I've seen centimeters marked on yardsticks frequently, but not on quilting rulers. My Olfa mats don't have metric. None of the Olfa products I can find online have both inches and centimeters. They do have a mat that has metric on one side and inches on the other, and they have rulers that are metric only. Did you buy your Olfa rulers in another country?