Span Calc by American Wood Council is a utility tool designed to assist in calculating joists and rafter spans for various loading conditions. This app supports all species and grades of softwood and hardwood lumber as per the 2021 National Design Specification (NDS) for Wood Construction. Users can compare spans for different species and grades using the span options calculator, making it a versatile tool for construction professionals and DIY enthusiasts alike.

The calculations are based on specific assumptions, such as vertical loads applied to the narrow face of the member, single-span configurations with proper support at each end, and specific minimum bearing lengths as per building codes. Span Calc focuses on combinations of dead load plus live load, snow load, or roof live load, omitting wind and seismic loads. Users are encouraged to consult local building codes for specific requirements and ensure compliance with engineering practices.