Floor Joist Calculator Widget | Calculator Campus

Primary output 13 ft 8 in (13.68 ft)

Occupancy preset Select the planning load preset. Preset values override the hidden live-load, dead-load, and deflection fields unless you choose custom loads.

Clear joist span / floor length (ft) (required) Measure the unsupported span parallel to the joists, from bearing to bearing.

Floor width across joists (ft) (required) Measure perpendicular to the joists; this drives joist quantity.

Nominal joist size (required) The calculator uses dressed dimensions, such as 1.5 in × 9.25 in for a 2×10.

On-center joist spacing (in) (required) Common residential spacings are 12, 16, 19.2, and 24 inches on center.

Advanced options

Advanced calculation branch (required) Keep the default sawn-lumber span check, switch to representative engineered lumber, or run a quantity-only layout estimate with no span check.

Actual thickness override (in) Leave blank to use the dressed thickness for the nominal size.

Actual depth override (in) Leave blank to use the dressed depth for the nominal size.

Wood species (required)

Lumber grade (required)

I-joist / LVL series (required) Choose a representative engineered-lumber series, then verify final selection in the manufacturer's current guide.

Live load (psf) (required) Only used when Occupancy preset is Custom loads.

Dead load (psf) (required) Only used when Occupancy preset is Custom loads.

Deflection limit L / ? (required) Only used when Occupancy preset is Custom loads. L/360 is common for residential floors.

Joist hanger type (required)

Maximum allowable span 13 ft 8 in (13.68 ft)

Span status Entered span exceeds the calculated allowable span; choose a deeper/stronger joist, tighter spacing, or engineering review.

Floor joists quantity 10 joists

Total lineal feet 184.0 ft

Controlling limit state Bending

Actual deflection at entered span 0.710 in

Bending demand/capacity ratio 1.37

Line load on each joist 53.3 plf live + 13.3 plf dead = 66.7 plf per joist

End/rim joist count 2 rim/end joists

Joist hanger count 20 hangers

Review note Verify final member selection against local code, current span tables, and field conditions.

Calculation basis 2x10 Spruce-Pine-Fir (SPF) No. 2 at 16 in. o.c.; allowable span is the shorter of bending and deflection limits for a simply supported uniform-load member.

Show calculation details

Member basis 2x10 Spruce-Pine-Fir (SPF) No. 2

Load preset Living area: 40 psf live + 10 psf dead

Deflection limit L/360

Calculation model Single-span uniform-load planning check