Divide your deck into segments while looking at the detailed deck plans for guidance.
Write each segment down on a piece of paper. Segments include framing, deck flooring, and railings at the very least.
Count up the boards necessary for each segment, dividing the boards up by dimensions. For example, count up the number of 2-by-4s, 4-by-4s, and 2-by-6s.
Record the number of each type of board necessary on the paper under the appropriate segment.
Add the number of boards of each type required, creating a master list of lumber necessary.
Add 10 percent more wood to your framing requirements and 15 percent more wood to your decking requirements. This ensures you will have enough wood.