Joist Calculator

Enter your floor or deck dimensions to estimate joists, rim boards, and bridging — then compare material costs across joist sizes.

Joist Calculator

Joist Spacing

Joist Size

Joist Span (ft)

Frame Width (ft)

Rim/Band Boards (1=yes)

Rows of Bridging

Waste Factor (%)

Pricing (edit to match local rates)

2×6 per piece ($)

2×8 per piece ($)

2×10 per piece ($)

2×12 per piece ($)

Rim Board ($/LF)

Bridging per set ($)

Joist Layout

Hover for details • structural cross-section

Joists Needed

16 + 10% waste

Rim Board

40 LF

both sides

Bridging Sets

1 row of cross bracing

Total (2×8)

$302.50

joists + rim + bridging

Joist Size	Quantity	Est. Cost
2×6 JoistsBest value	18 joists	$257.50
2×8 Joists	18 joists	$302.50
2×10 Joists	18 joists	$374.50
2×12 Joists	18 joists	$446.50

Lowest material cost: 2×6 at $257.50Smaller joists cost less per piece but may not meet span or load requirements. Always verify your joist size against span tables for your species, grade, and live/dead load before ordering.

This is a material estimate only. Joist size must be verified against span tables for your lumber species, grade, and expected loads. Always follow your local building code and engineered plans.