Floor Joist Span Calculator Floor Joist Span Calculator Determine the maximum allowable span based on joist size and spacing. * Values are in feet.Step 1: Enter Joist Details Joist Size: 2×62×82×102×12 Select the nominal joist size. On-Center Spacing (inches): 12″ O.C.16″ O.C.24″ O.C. Select the spacing between joists. Calculate Span Maximum Span ResultMaximum Span: New Calculation
