Help!!! Ikea 1.5″ Drain To 1.25″

I recently purchased a new sink and vanity from Ikea, my problem which I am sure is common is that the pipes and p-trap from ikea ar 1.5 inches and my pipe coming out of the wall is 1.25 inches, how do I get the 2 to work. what do I need to get? Thanks in advance.