swimming comparison to walking and running

I'm in a new class for a comprehensive lifestyle change, mainly transitioning to a vegan diet. Of course, exercise is a part of this, and I exercise quite a bit. We are to wear a pedometer to keep track of the miles we walk everyday. I swim a mile everyday and would like to know if anyone knows how to convert swimming or compare swimming to walking. I've searched the web, and get different answers. Help?:)