Because most of the patterns are in inches and it's very difficult to convert I always use inch-rulers.

Personally, I wouldn't encourage her to convert inches to centimetres.

We are metric here, but every quilter I know uses Imperial. We do have to buy our fabric and ribbon etc by the metre however, so I usually buy 0.9 if I want a yard. Virtually everything quilt-related will be given in inches and parts thereof.

However, if she insists, the easiest way is to have a two-sided tape measure and flip it over to see the sizes. Also, one of my Olfa mats has a metric side and I know that Omigrid do a metric ruler.

I'm in Poland. I've taught my friend to use inches. I gave her an inch ruler and an inch cutting board. I'm sure anyone can learn to use a different system. I definitely would not encourage my friend to try to convert everything to the metric system when the measuring instruments are in inches.

They sell tvs in inches and laptop screens in inches. Even in Poland. They use the metric system here.

I agree with Knittette... simply sew and quilt using 1/4", etc. The reason we teach American students the "metric" system is that virtually every country in the world uses the "metric" system. In addition, virtually all of science is done using this system. The reason it appeals to scientists is that all "metric" measurements are based on units of 10! It is MUCH easier to multiply and divide by 10 (in order to convert from one unit to another) than it is to multiply or divide by 12 (inches to feet), or 16 (ounces to pounds), for example. Once you really learn the system, it is so much easier to use! My DH hopes it doesn't happen in his lifetime, though... he sells auto parts and hardware... NOT "metric" at all....

The only time I heard of anyone converting was inches to metric because she wanted to enlarge a Hawaiian quilt pattern she saw in a magazine from a 3 " square picture to a queen size bed quilt. She tried using inches but it just wouldn't work - when she changed to metric it came out.

I have a dumb phone, but it still has a converter on it. I was playing with it today. Worth a look?

chrome://calculator/content/calculator.xul
This free calculator does conversions if you really need them. I'm metric but quilt in imperial but mostly sew(garments) using metric patterns.
For your 1/4 seam allowance there's no need to convert as your 1/4" is (approximately) 0,6 which is used in metric. I use conversions only when I'm not sure how much fabric to buy or to visualize the size of a project. Otherwise I 'm fine with inches. By the way, when you think metric (1m for 1yd) you never run short as 1 meter equals to 39,37 inches! I' attaching a table of conversions, just in case. Have fun!

Over her in the UK we are metric for everything. In shops we purchase our fabric in metres. When we quilt we do it all in inches. None of use appear to have a problem not even the youngsters. If all her equipment is in inches it will be easy to follow a pattern just follow numbers. Converting to make really accurate triangles for a beginner will be very difficult. I would if she insists to buy a ruler with inches and centimetres on. She only has to pull out and look at sizes. I know that centre metres rulers squares are made , but it is going to be very time consuming and may stop the enjoyment.

Like the above poster I'm in the uk, and most of our stuff is metric. I was taught metric in school, but still manage to use inches just fine for quilting.

I buy fabric in metric measurements, but when you think of a 15cm ruler you know that is 6 inches, as they nearly always have both printed so you get used to it. I can usually extrapolate from there how much fabric I want to buy.