Attic Ventilation Calculator | Bearmark Roofing & Insulation

1. Tell us about your attic

Use your attic floor area — not roof surface area or total home square footage.

Attic floor area (sq. ft.)

Measure the flat floor where you can walk — see the guide on the right.

Current intake ventilation

Current exhaust ventilation

Any of these sound familiar?

Upstairs stays hot High electric bills AC runs constantly Uneven room temperatures Moisture / musty smell Insulation looks thin

How to measure your attic

Use attic floor area, not full home square footage

Measure the attic floor where you can actually walk, then multiply length × width to get the square footage.

Diagram of an attic cross-section showing how to measure the flat attic floor using length times width, with a note not to use the home's total square footage or the sloped roof surface area.

Measure the flat attic floor — not the sloped roof surface above it.
Don't use your home's total living square footage unless the attic floor actually matches it.
If the attic has multiple separate sections, measure each one and add them together.

Bearmark tip: not sure what to measure? We verify attic size, ventilation, and insulation depth during every free inspection — this tool is just a starting point.

Your Bearmark Ventilation Snapshot

Your results

This is a quick screening estimate, not a substitute for an in-person inspection or local code review.

Total Ventilation Needed —

sq. in. NFVA

Recommended Intake —

sq. in. NFVA

Recommended Exhaust —

sq. in. NFVA

Bearmark Attic Screening Score

Higher means fewer red flags in your answers — not a pass/fail grade, just a starting point for the conversation.

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Estimated Ventilation Plan

Bearmark Roofing & Insulation

Free attic & roof inspection

Want us to verify the numbers in person?

Blocked soffits, covered intake vents, roof geometry, insulation depth, and mixed exhaust systems can all change how an attic actually performs. A quick on-site visit confirms whether your attic matches this estimate.

Educational estimate only. Actual ventilation needs vary by roof design, climate, existing insulation, vapor-retarder conditions and vent manufacturer specifications. Bearmark verifies conditions on site before recommending or installing any ventilation products.

Is Your Attic Breathing Right?

1. Tell us about your attic

Use attic floor area, not full home square footage

Your results

Estimated Ventilation Plan

Want us to verify the numbers in person?

Prefer to talk it through first?