Helping my mother-in-law with a framing project just the other day, she was dismayed to discover that the store-bought 5x7" frames all had openings of 4.5x6.5...

I prefer to buy the "raw ingredients" - custom framing and matting materials - and put it all together myself, that way I can decide how big everything needs to be. Having said that, I stink at mat-cutting.