The pitch is to be 1:12. That means that for every inch of raised floor height add 12” of ramped surface accessing the floor. EX: If you have a 6” raised floor, you will need a 6’ ramp. If you have an 18” raised floor, you will need an 18’ ramp.
Minimum 36” wide
If the ramp is over 6’ long, it must be a non-skid surface or have adequate slip protection strips installed. Many people have 6’ long carpeted ramps.