Question: I have a concrete floor and I made two holes to bolt a 1/4"-thick steel plate. The problem is that the steel plates haven't been drilled yet.

How can I determine where the holes will be drilled in the steel plates so they match the holes in the concrete?
[![enter image description here](https://i.stack.imgur.com/1Kt5n.png)](https://i.stack.imgur.com/1Kt5n.png)

Answer: 
Lay the steel plate on the concrete where you want it. Draw a line around it. Cut a piece of paper to the same size as the steel plate. Place it on the concrete in the same position as the marked outline. Locate the concrete holes by gently pressing down where you think they are (tracing paper makes this even easier). Poke a hole through the paper at the center of each hole. Place the paper on top of the steel plate, and mark the centers of the holes.
I like Mark's answer best (create a paper template and mark the holes) but another technique came to mind.

Take a straightedge and a construction pencil.  

- Mark the centerline of the two holes longer than your steel plate.  

- Mark a line perpendicular, on each hole, wider than your plate.
- Put the plate down, use your straightedge and the marks to locate the hole centers.

[hmm. similar but different to Stanwoods solution which I did not see at first]