I was raised on imperial, and everything changed to metric in '66, a month after I was married, so am familiar with both. This is how I see things regarding quilting, if a little rough.
2.5cm (25mm) = 1"
30 cm = 1ft
1 mtr = 39.?"
1.5mtrs = 60"
2 mtrs = 80"
2.5mts = 100"
These aren't precise measurements but it's easier to wrap my brain around.