Nail-less, glue-less almost screw-less fire finished bed

Step 2 Measuring and Measuring and then cutting

So, take your boards and put them beside your mattress to be sure you will have a perfect fit.
Mark the boards with a pencil on one side and measure the lenght and width of your mattress. You need to measure only one side, obiously the other side should be the same (unless is a weird non-square mattres)