The bright spot about being ignorant is you don't realize how complicated a question can be. Original question: Two sledge hammers, one is 10lb with 5.062 sq in striking face. One is 16lb with 8.265 sq in striking face. I was asking for the difference in force between the two. Things being equal: handle length, speed, head material, striking material. Then questions arose about impact time (steel vs. wood) head material (soft steel vs hard steel) and speed (pick one. Don't really care. How fast can you swing it from over your head to 1' above the ground?) My mind went south. To the beach. All this for a simple article I'm writing on using the correct tools. I'm rephrasing my question. Is there something that will give me a percentage difference in the impact per square inch? I know it's not a simple ratio of different weights, as the impact faces are different. I've killed a lot of electrons looking for an answer to this. Anything you have would be appreciated.