Attic Ventilation Baffle Calculator
Estimate attic ventilation baffles for vented eaves using eave length, rafter spacing, baffle run length, stock-piece length, waste and package size.
Default project preview
2 packs
Bays per eave side
24
Pieces per bay
1
Base baffle pieces
48
Purchased baffles
100
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.
Rafter bays = eave length ÷ spacing, rounded up. Multiply by vented sides and stock pieces per baffle run, add allowance, then round to packs.
BuildMeter Guides
Understand the measurements and assumptions
Use these visible reference guides before changing project inputs or planning allowances.
FAQ
Attic Ventilation Baffle Calculator questions
Does every rafter bay need a baffle?+
Count bays that receive intake air according to the attic ventilation design. Unvented assemblies use different moisture and insulation details.
Why might one bay need more than one piece?+
The required chute run can extend farther upslope than one stock baffle, especially with deep insulation near the eave.
Does this size the attic ventilation system?+
No. It estimates chute pieces after the vented bays and run length have been established.