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: 
Since nobody else has mentioned it, I'll add another option that I've used in the past for spacing holes.

1. Put some paint on the floor around the holes.
2. While the paint is still wet, place the metal plate on the floor.

When you remove the metal plate from the floor, the wet paint will have transferred to the plate but will leave two spots behind where the holes were. Mark those spots, clean up the wet paint, and drill.

This also works great for spacing screw holes for handles on cabinets & drawers although I would usually use lipstick for those instead of paint.
An alternative to Mark's idea would be to use plexiglass. Lay that down and mark either the center of the holes or the holes themselves. Drill through the plexiglass, make sure the holes are aligned properly, and then use that as a template to drill holes in the steel.

I would have added this as a comment under his answer but I don't have 50 reputation yet.