How to Estimate a Roofing Job: A Contractor's Complete Guide
Roofing estimates are where a lot of contractors lose money — either by underpricing the job or spending so long building the estimate that someone else wins the bid. This guide covers how to estimate a roofing job the right way, from measuring the roof to sending a professional quote.
Step 1: Measure the Roof in Squares
Roofing is priced in squares — one square = 100 square feet of roof surface. To measure:
- Measure the footprint of the house (length × width)
- Multiply by the pitch factor to get the actual roof area
| Roof Pitch | Pitch Factor |
|---|---|
| 4/12 | 1.054 |
| 6/12 | 1.118 |
| 8/12 | 1.202 |
| 10/12 | 1.302 |
| 12/12 | 1.414 |
Example: 2,000 sq ft footprint × 1.118 (6/12 pitch) = 2,236 sq ft = 22.4 squares
Always round up to the nearest half square. Then add 10–15% for waste — more for complex roofs with hips, valleys, and dormers.
Step 2: Count Everything That Needs to Be Done
A roofing estimate isn't just shingles. Walk the job and note:
- Layers to remove — Is it a tear-off or overlay? Each existing layer adds labor and disposal cost
- Decking condition — How much rotted OSB or plywood is likely? Budget for 5–10% replacement on older roofs
- Flashings — Chimney, pipe boots, step flashing, drip edge — all need to be replaced or reused
- Ridge and hip length — Measured separately for ridge cap shingles
- Valleys — Open metal or closed cut? Different labor and material
- Gutters — Are they being removed and re-hung, or worked around?
- Skylights — Each one adds 1–2 hours of labor
- Permit — Most jurisdictions require one for a full re-roof
Step 3: Price the Materials
For a standard architectural shingle re-roof, you'll need:
| Material | Rule of Thumb |
|---|---|
| Shingles | 1 square per square + 15% waste |
| Underlayment (synthetic) | 1 square per square |
| Starter strip | 1 bundle per 100 lin ft of eaves |
| Ridge cap | 1 bundle per 35 lin ft of ridge/hip |
| Drip edge | 1 piece per 10 ft of perimeter |
| Pipe boots | 1 per penetration |
| Roofing nails | 1 lb per square |
Current market prices (2024–2025):
- Architectural shingles: $90–$130/square (mid-grade)
- Synthetic underlayment: $15–$25/square
- Drip edge: $1.50–$3/linear ft
- Starter strip: $40–$60/bundle
Price at retail rates — not your supplier cost. Your material markup (10–20%) covers handling, returns, and waste.
Step 4: Estimate Labor
Roofing labor varies by crew size, pitch, and complexity. A standard 2-person crew can typically:
- Tear off: 15–20 squares/day
- Install: 20–25 squares/day
For a 25-square re-roof with a moderate pitch:
- Tear-off and haul-off: 1 day
- Installation: 1 day
- Total: 2 crew-days = ~16 man-hours
At $75–$95/hour per man, that's $1,200–$1,520 in labor for a straightforward job. Add more for steep pitches (>8/12), multiple penetrations, or complex roof geometry.
Step 5: Add Disposal and Overhead
- Dumpster rental: $350–$600 depending on size and market
- Permit: $200–$800 depending on jurisdiction
- Miscellaneous (caulk, flashing cement, nails): $50–$150
Sample Estimate: 25-Square Re-Roof
| Line Item | Qty | Unit | Unit Price | Total |
|---|---|---|---|---|
| Tear-off, 1 layer | 25 | sq | $45 | $1,125 |
| Haul-off & disposal | 1 | job | $450 | $450 |
| Synthetic underlayment | 25 | sq | $22 | $550 |
| Starter strip | 2 | bundle | $55 | $110 |
| GAF Timberline HDZ | 25 | sq | $115 | $2,875 |
| Ridge cap | 3 | bundle | $65 | $195 |
| Drip edge | 180 | lin ft | $2.50 | $450 |
| Pipe boots (3) | 3 | each | $35 | $105 |
| Labor — tear-off | 8 | hr | $85 | $680 |
| Labor — installation | 10 | hr | $85 | $850 |
| Permit | 1 | job | $350 | $350 |
| Subtotal | $7,740 | |||
| Overhead & profit (18%) | $1,393 | |||
| Total | $9,133 |
Step 6: Get It Out Fast
In roofing, speed wins. Homeowners dealing with a leak or storm damage are calling multiple contractors. The first professional quote in their inbox usually gets the job.
Record your walkthrough with Bid.Fast — talk through the squares, the pitch, the layers, any special conditions — and the app builds this estimate for you in 90 seconds. Review it, adjust anything, and send the client a link they can approve with one tap.
Try 3 free roofing estimates →
Common Roofing Estimating Mistakes
Forgetting decking repair — Always budget for some rotted wood. When you find it during tear-off and didn't price it, you eat it.
Not charging for steep pitch — A 10/12 or 12/12 pitch adds 20–30% to labor. Price it in.
Underpricing disposal — A full tear-off generates a lot of debris. Dumpsters fill up. Price haul-off as a real line item.
Not including permit cost — Many roofers absorb this. Don't.
Using last year's shingle prices — Material costs fluctuate. Update your pricing before every proposal season.
Bid.Fast is a voice-to-estimate app built for roofing contractors. Walk the job, record your notes, and get a complete itemized estimate in 90 seconds. Start free →