1. To ensure that the size of something complements or is proportional to the size of something else. We'll need to scale these photos to the picture frames I picked out. The architect wants to scale the extension to the rest of the house, but I'd really like for it to be quite a bit bigger than he's suggesting.

2. To adjust or design something to have a particular proportional size. Because the picture is a square, it won't scale to a standard 4x6 print unless we crop part of it out. The artist scaled the entire model city to just 1/1000ths of the real New York City, while still maintaining an astounding level of detail and accuracy.