TheRoofBillEstimate

How We Calculate Roof Costs

Last updated: October 2026. We publish our model because a calculator you can't inspect isn't worth trusting.

The formula, in plain English

Estimated cost = (base installed $/sq ft x pitch multiplier x shape multiplier x state labor multiplier x access factor) + tear-off + permits + 10% decking contingency + add-ons.

  • Base installed $/sq ft - per material, from 2026 public cost data (ranges, e.g. architectural asphalt $5.21-6.82).
  • Pitch multiplier - 1.00 for walkable 4/12-6/12 roofs up to 1.60 for 10/12+ (steeper = slower, safety gear).
  • Shape multiplier - 1.00 simple gable, 1.12 hip, 1.28 complex (dormers/valleys waste more material).
  • State labor multiplier - from BLS roofer wage data: ~0.80x (Mississippi) to ~1.45x (Hawaii) of the national median.
  • Access factor - 1.00 / 1.05 / 1.10 for 1 / 2 / 3 stories (staging and access difficulty).
  • Tear-off - $39-53 per roofing square per layer for asphalt; $50-95 for metal/tile/slate.
  • Permits & disposal - $300 default, scaled up to 1.6x at the high end.
  • Decking contingency - 10% of the base, because rotten decking is found mid-job more often than not.

Worked example

2,000 sq ft footprint, 1 story, medium pitch (6/12), simple gable, architectural asphalt, Texas, 1 layer tear-off:

  • Roof area: 2,000 x 1.12 (pitch slope) = ~2,240 sq ft
  • Base: 2,240 x $5.21-6.82 x 1.00 x 1.00 x 0.98 x 1.00 = ~$11,400-$15,000
  • Tear-off: 22.4 squares x $39-53 = ~$875-$1,190
  • Permits: $300-$480; decking contingency: ~$1,140-$1,500
  • Total: roughly $13,700-$18,200

Data sources

  • Homewyse unit-cost data (September 2026)
  • Angi 2026 roof replacement cost guide
  • Fixr 2026 cost guides
  • BLS Occupational Employment & Wage Statistics, May 2025 (SOC 47-2181, Roofers)
  • Remodeling Magazine Cost vs. Value 2025

What we don't include

  • Gutters, fascia beyond the roof edge, and interior repairs - separate jobs.
  • Structural repairs beyond decking (rafters, trusses) - priced per-job by contractors.
  • Financing costs.

Limitations

State labor multipliers are estimated from BLS wage ratios - real quotes in hot markets (post-hurricane Florida, wildfire-rebuild zones) can exceed our high end. Material prices move with oil, steel, and lumber markets. We refresh base figures quarterly; the changelog below records each update.

Update changelog

  • October 2026 - Initial model published. Base figures: Homewyse September 2026, Angi 2026, Fixr 2026. Labor: BLS OEWS May 2025.

Corrections

Found a figure that's off? Email us via the contact page with your source and we'll verify and update - with credit.