Joist Calculator
Pieces = floor(span ÷ spacing) + 1.
Step 1: Units
Step 2
Enter project measurements
Use decimals if needed (e.g. 3.5).
How to use this calculator
Span perpendicular to joists.
What the math is doing
Pieces = floor(span ÷ spacing) + 1.
Frequently asked questions
Bearing walls?
May change span breaks.
Cantilever?
Engineering required.
Hangers?
Count per joist end.
Blocking?
Mid-span rows separate.