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Floor Joist Span Chart

Compare maximum clear spans for 2×6, 2×8, 2×10 and 2×12 No. 2 floor joists at 12, 16, 19.2 and 24 in. on center, then check the smallest listed size for your span.

Floor Joist Span Chart — No. 2 Lumber

Start here: maximum clear spans for No. 2 solid-sawn dimensional-lumber joists in residential living areas at 40 psf live + 10 psf dead load and L/360.

Maximum Clear Span at 16 in. O.C.

No. 2 · 40/10 psf · L/360

The quick chart is shown as a compact table on wide screens and stacked joist cards on narrow screens.

Joist Douglas Fir–Larch Hem–Fir Southern Pine Spruce–Pine–Fir
2×69 ft 9 in9 ft 1 in9 ft 4 in9 ft 4 in
2×812 ft 9 in12 ft 0 in11 ft 10 in12 ft 3 in
2×1015 ft 7 in15 ft 2 in14 ft 0 in15 ft 5 in
2×1218 ft 1 in17 ft 7 in16 ft 6 in17 ft 10 in

Not sure which species you have? Read the grade stamp on the joist. Do not assume the longest value in the row.

JavaScript is optional. The 16 in. o.c. quick chart and the complete 12–24 in. reference table remain readable below.

Bedroom or heavier floor? Sleeping areas use a 30 psf live-load table, while some heavier floor assemblies use a 20 psf dead-load case. This chart stays on the common 40 psf live + 10 psf dead living-area condition so the first lookup remains unambiguous; see when this chart does not apply.

Complete No. 2 Floor Joist Span Table

All four common spacings are shown; the 16 in. o.c. column matches the quick-chart selection above.

Scroll horizontally to compare all spacing columns. The species column remains visible while scrolling.

Maximum clear spans for No. 2 solid-sawn floor joists, residential living areas, 40 psf live load, 10 psf dead load, L/360 live-load deflection. Verify the locally adopted code and project conditions before construction.
Species group Joist size 12 in. o.c. 16 in. o.c. 19.2 in. o.c. 24 in. o.c.
Douglas Fir–Larch2×610 ft 9 in9 ft 9 in9 ft 2 in8 ft 3 in
Douglas Fir–Larch2×814 ft 2 in12 ft 9 in11 ft 8 in10 ft 5 in
Douglas Fir–Larch2×1018 ft 0 in15 ft 7 in14 ft 3 in12 ft 9 in
Douglas Fir–Larch2×1220 ft 11 in18 ft 1 in16 ft 6 in14 ft 9 in
Hem–Fir2×610 ft 0 in9 ft 1 in8 ft 7 in7 ft 11 in
Hem–Fir2×813 ft 2 in12 ft 0 in11 ft 3 in10 ft 2 in
Hem–Fir2×1016 ft 10 in15 ft 2 in13 ft 10 in12 ft 5 in
Hem–Fir2×1220 ft 4 in17 ft 7 in16 ft 1 in14 ft 4 in
Southern Pine2×610 ft 3 in9 ft 4 in8 ft 6 in7 ft 7 in
Southern Pine2×813 ft 6 in11 ft 10 in10 ft 10 in9 ft 8 in
Southern Pine2×1016 ft 2 in14 ft 0 in12 ft 10 in11 ft 5 in
Southern Pine2×1219 ft 1 in16 ft 6 in15 ft 1 in13 ft 6 in
Spruce–Pine–Fir2×610 ft 3 in9 ft 4 in8 ft 9 in8 ft 1 in
Spruce–Pine–Fir2×813 ft 6 in12 ft 3 in11 ft 6 in10 ft 3 in
Spruce–Pine–Fir2×1017 ft 3 in15 ft 5 in14 ft 1 in12 ft 7 in
Spruce–Pine–Fir2×1220 ft 7 in17 ft 10 in16 ft 3 in14 ft 7 in

Clear span is measured face-to-face between supports. These values are not for I-joists, LVL, floor trusses, cantilevers, concentrated loads, damaged/notched members, or unidentified lumber.

How to Measure Floor Joist Span and Spacing

Use clear span, not total board length.

Clear floor joist span measurement A joist rests on two supports. Clear span is measured from the inside face of one support to the inside face of the other. CLEAR SPAN Measure between support faces
Clear span: face-to-face between adequate supports, not the joist’s overall length.
SpanMeasure horizontally between the inside faces of the beam, wall or other adequate supports.
O.C. spacingMeasure from the centerline of one joist to the centerline of the next.
Grade stampUse the species group and grade shown on the lumber stamp; this chart is No. 2 only.

How to Use the Floor Joist Span Chart

  1. Measure the clear span between support faces.
  2. Confirm the joist spacing — 12, 16, 19.2 or 24 in. on center.
  3. Read the lumber stamp and match the species group; this page is for No. 2 grade.
  4. Find the size whose tabulated maximum is equal to or greater than your required span.

Common case: for a 14 ft living-area span at 16 in. o.c., No. 2 Douglas Fir–Larch, Hem–Fir and Spruce–Pine–Fir 2×10 values exceed 14 ft, while Southern Pine reaches 14 ft exactly. That is why species matters.

Floor Joist Span by Size

For the common 16 in. o.c. condition shown above, No. 2 lumber spans vary by species. Use the full chart for the exact value.

2×6 Floor Joist Span

9 ft 1 in to 9 ft 9 in at 16 in. o.c. across the four listed species groups.

2×8 Floor Joist Span

11 ft 10 in to 12 ft 9 in at 16 in. o.c. across the four listed species groups.

2×10 Floor Joist Span

14 ft 0 in to 15 ft 7 in at 16 in. o.c. across the four listed species groups.

2×12 Floor Joist Span

16 ft 6 in to 18 ft 1 in at 16 in. o.c. across the four listed species groups.

What Changes a Floor Joist’s Maximum Span?

Joist depth
Deeper joists are much stiffer and generally span farther under the same loading.
On-center spacing
Closer spacing reduces the floor load carried by each joist and generally increases allowable span.
Species and grade
Strength and stiffness vary by species group and grade, so nominal size alone is not enough.
Floor loading
Bedrooms, general living areas and heavier permanent finishes can require different span-table load cases.

Installing tile, stone or a heavy floor assembly?

Do not assume the 10 psf dead-load chart applies. Heavier assemblies can reduce allowable span, and brittle finishes may have additional stiffness requirements.

When This Floor Joist Span Chart Does Not Apply

  • Engineered products: I-joists, LVL, PSL and floor trusses require manufacturer or engineered design information.
  • Different grade/load case: No. 1, No. 3, Select Structural, sleeping-area tables, or heavier dead loads require the corresponding verified table.
  • Nonstandard loading: bearing walls, tubs, masonry, point loads, openings, cantilevers or unusual vibration criteria need separate checks.
  • Existing or altered joists: excessive holes/notches, decay, splits, fire damage, unknown grade/species, or inadequate bearing can invalidate a simple span-table lookup.

Sources and Engineering Assumptions

Displayed reference: No. 2 solid-sawn dimensional lumber · residential living area · 40 psf live load · 10 psf dead load · L/360 live-load deflection · clear span measured face-to-face between supports.

The chart is a screening/reference aid, not a project-specific structural approval. Confirm the locally adopted code, grade stamp, loads, bearing, lateral restraint, holes/notches and other project conditions.

Floor Joist Span FAQs

For No. 2 lumber at 16 in. o.c. under the 40/10 psf living-area condition on this page, 2×10 spans range from 14 ft 0 in for Southern Pine to 15 ft 7 in for Douglas Fir–Larch. Species, grade, spacing and load case can change the answer.

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