How to use the roof replacement cost calculator
- Enter the footprint and pitch, or a known roof area.
- Choose the shingle type.
- Override the rate with local quotes if you have them.
- Add extras like decking replacement or new gutters.
Formula
Roof area = footprint × √(1 + (pitch ÷ 12)²). Cost = roof area × installed cost per sq ft + extras.
Worked example
A 42 × 30 ft footprint at 6/12 has about 1,409 sq ft of roof. With architectural shingles at $4–$8 per sq ft, roughly $5,635–$11,270 before extras.
Tips for using the roof replacement cost calculator
- Ask whether quotes include tear-off of old layers and replacement of damaged decking.
- Steep, complex or multi-story roofs raise labor costs beyond the per-square average.
- Compare quotes on the same shingle line, underlayment and warranty.

Roof Replacement Cost Calculator FAQs
How much does a new roof cost?
National cost data show an average of $12,000 to replace an asphalt shingle roof, with most projects between $8,000 and $16,000 (updated January 2026).
How much does a roof cost per square?
At $4–$8 per sq ft for architectural shingles, about $400–$800 per square (100 sq ft).
Do I need a permit to replace my roof?
Rules vary. In NYC, the Department of Buildings lists non-structural roof repair among work that does not require a permit, while landmarked buildings may still need LPC approval. See our roofing guide.
