The NCEES and many of the state licensing boards specify a minimum of 50 minutes contact time to qualify for one (1) PDH. Other state licensing boards are not explicit in their rules about this topic and the implication is that a full 60 minutes of contact time is required to earn one (1) PDH. For example, the Ohio Board of Engineers and Surveyors lists the following in their CPD Conversion chart: 1 hour of attendance at a conference, seminar or workshop = 1 CPD hour.