How do you estimate roof cost by square footage?
Why the conversion matters
Listing square footage counts heated living space on every floor. The roof only covers the footprint, plus overhangs, stretched by the slope. Two homes listed at 2,400 square feet can have roofs that differ by half.
Rough roof sizes before garages
- 1,200 sq ft, one story: about 14 to 16 squares.
- 1,800 sq ft, one story: about 21 to 24 squares.
- 2,400 sq ft, two story: about 14 to 17 squares.
- 3,000 sq ft, two story: about 18 to 21 squares.
One square is 100 square feet of roof. The low end assumes a gentle 4/12 pitch, the high end a steeper 8/12.
Add what the listing leaves out
An attached two car garage commonly adds 5 to 8 squares. Covered porches, carports, and bonus rooms over garages add more. Then add 10 to 15 percent waste for ordering.
Match to a range
Smaller simple roofs in North Georgia run roughly $7,000 to $11,000, most homes $8,000 to $16,000, large roofs $15,000 to $25,000, and steep or complex roofs $20,000 and up.
Where this method breaks down
Vaulted ceilings, multiple rooflines, and steep pitches throw off any ratio. A measurement from the roof itself is always better; see how roofers measure a roof and roof replacement cost in Georgia.