Floor Joist Calculator
Estimate floor-joist positions, field stock, rim-board stock, blocking rows, total lumber length and preliminary material cost.
Default project preview
28 pieces
Field joist pieces
20
Rim stock pieces
3
Blocking stock pieces
2
Total stock length
448 ft
Calculator
Build the material order
Your order will appear here
Enter the project details and calculate a rounded material estimate.
Methodology
Transparent calculation
BuildMeter converts every input to a consistent internal unit, applies the selected allowance, and rounds products up to whole purchasable units.
Joist positions = round up (layout width ÷ spacing) + 1. Field stock, rim stock and blocking stock are added, then the waste allowance is rounded to full pieces.
FAQ
Floor Joist Calculator questions
Why is one extra joist position added?+
A framed run needs a member at both ends, so spacing intervals produce one more member position.
Does this verify joist span?+
No. Allowable span depends on lumber or engineered-product data, loading, spacing and code.
Are blocking pieces exact?+
The estimate converts total blocking-row length into stock pieces; actual bay cuts and offcut reuse affect the order.