1. Measure the usable deck surface
Measure the finished decking footprint in feet, not the lot size or roof footprint. For a rectangular example, a 16 ft by 12 ft surface covers 192 square feet. Verify the actual finished outline including any trim or picture-frame boards, which are not included in our simple estimate.
2. Decide the direction of the decking
Board direction changes the number of courses and the joints required. A board laid parallel to the 16 ft side runs 16 ft and the courses stack across the 12 ft side. A board laid parallel to the 12 ft side runs 12 ft and the courses stack across the 16 ft side. Joist support and allowable orientation must be verified independently.
3. Read actual board size and installation gap
A nominal 6-inch board may have a roughly 5.5-inch actual face width, but specific products vary. Use the exact manufacturer dimensions and required spacing. The calculator allows custom face width and gap rather than assuming every board is the same.
4. Plan for offcuts and joints
If a run exceeds the selected stock length, the calculator counts multiple pieces per course and flags the need to check end-joint support. This conservative count does not reuse offcuts across rows and does not generate a staggered installation plan. Complex geometry, diagonal layouts, stairs, border boards and herringbone patterns need a separate material takeoff.
5. Confirm before purchasing
Check framing, permits, hardware, stairs, railings, flashing, manufacturer instructions and local requirements with qualified professionals where appropriate. This website is not a structural design or permit plan.