I don't sew with plaid very often - mostly just to make flannel shirts for my Grandmother. But I know that you're supposed to buy extra fabric to allow for matching the stripes in assorted locations - across the front of the shirt, etc.
I don't really have a good sense of how much extra to buy - I imagine that it would depend on things like the size of the stripe.
How about you? Do you sew very often with plaids and other fabric designs that need to be carefully aligned? If so, how do you decide how much extra fabric to buy?
Photo credit: GLAMCHIC