Floor Joist Calculator
Calculate floor joists needed from room length, width, and joist spacing (12", 16", or 24" OC).
feet
feet
Joist Estimate
—joists
Joist Length—
Board Feet—
Rim Boards—
Floor Joist Spacing
Standard joist spacing is 16" on center (OC). Use 12" OC for heavy loads or tile floors. 24" OC is acceptable for light loads with engineered lumber.
Joist Span Table (Residential)
| Joist Size | 16" OC Span | 12" OC Span |
|---|---|---|
| 2×6 | 9' 1" | 10' 0" |
| 2×8 | 12' 0" | 13' 2" |
| 2×10 | 15' 4" | 16' 10" |
| 2×12 | 18' 8" | 20' 6" |