Roof Vent Calculator
Enter your size to get roof vent quantity, plus an estimated cost. Waste is included and prices are editable.
Material needed
Estimated cost
How to calculate roof vent
Roof vents, about one vent per 300 square feet, with waste.
Formula: quantity = area × 0.0033 × (1 + waste %) = 100 × 0.0033 × 1.10 = 1 vents.
Worked example
Example: 10 ft × 10 ft = 100 sq ft. Quantity: 1 vents, about $50 at $50 per vents.
Tips
Measure the full area, then subtract large openings if you want an exact count. Order a little extra for cuts and breakage, and confirm quantities with your supplier before you buy.
Related calculators
Frequently asked questions
How much roof vent do I need?
Example: 10 ft × 10 ft = 100 sq ft. Quantity: 1 vents, about $50 at $50 per vents.
How much waste should I add?
Add 10% for straight areas and 15% for areas with many cuts, corners and openings.
Are the prices accurate?
Prices are editable estimates. The defaults are typical US figures, and your local price can be higher or lower.