Estimate floor joist span, joist line load, bending stress, shear stress, deflection, span ratio, and maximum allowable span. Use this floor joist span calculator for wood joists, dimensional lumber, engineered joists, floor framing, deck floors, and preliminary structural planning.
Load conversion:
The calculator converts dead load and live load in PSF into a joist line load using joist spacing.
Section properties:
The calculator uses joist width and depth to estimate area, section modulus, and moment of inertia.
Strength checks:
The calculator estimates bending stress and shear stress, then compares them to the entered allowable values.
Deflection check:
The calculator estimates joist deflection and compares it to the selected span limit.
A floor joist span calculator helps estimate whether a joist size and spacing may be reasonable for a given span and floor load.
It can help compare joist span, joist spacing, floor load, line load, bending, shear, deflection, and approximate maximum span.
Your result shows estimated joist line load, total load, support reactions, maximum moment, bending stress, shear stress, deflection, allowable deflection, span ratio, and estimated maximum span. These are planning estimates only.
Floor joist span is the distance a joist runs between supports, such as beams, bearing walls, girders, or rim supports.
Multiply the floor load in PSF by joist spacing in feet. For example, 55 PSF at 16 inches on center equals about 73.3 PLF before adding joist self weight.
Use actual joist dimensions. For example, a nominal 2×10 is commonly about 1.5 inches wide by 9.25 inches deep.
No. Final floor joist design should use approved span tables, species and grade values, local code requirements, bearing checks, vibration considerations, and professional review when needed.