About the site

Methodology

This page explains where every number on calcmyroof.com comes from, how the cost ranges are built, how often they are checked, and what they are not. If a figure on this site cannot be traced back to something listed here, that is a mistake and we want to hear about it.

Cost figures are reviewed periodically. Last reviewed: September 8, 2026.

All cost figures on this site are national estimates, not quotes. They are researched from the public sources listed below. Nobody involved in this site installs roofs, and we do not claim any field experience. What we add is collecting public data in one place, showing the arithmetic, and keeping it current.

The calculators are plain arithmetic

None of the calculators use pricing data, a database or anything hidden. They take the measurements you type in and apply formulas that are printed on the page next to every result, so you can check the working or repeat it by hand.

  • Roof Pitch Calculator: pitch = 12 × rise ÷ run; angle = atan(rise ÷ run); multiplier = √(rise² + run²) ÷ run; slope % = rise ÷ run × 100.
  • Roofing Square Calculator: footprint = length × width; roof area = footprint × pitch multiplier; squares = area ÷ 100; squares with waste = squares × (1 + waste %); bundles = squares with waste × 3, rounded up.

The only assumptions built into a calculator are stated on its page. The main one is 3 bundles per square, which is the packaging convention for standard three-tab and most architectural asphalt shingles. Heavier designer shingles can be 4 or 5 bundles per square, and the calculator page says so.

Where the cost figures come from

Cost pages on this site quote a low, mid and high figure per roofing square, and a total for typical roof sizes. Those ranges are built from four kinds of public source. Every link below was checked and working on the review date above.

1. Manufacturer product data

Used for product lines, coverage per bundle, bundles per square, warranty tiers and installation requirements. Manufacturers do not publish public price lists, so these pages are not used for prices.

2. Retail material pricing

Per-bundle and per-roll prices for shingles, underlayment, starter strip, ridge cap, drip edge and nails are read from the public online listings of Home Depot and Lowe’s at each review, using their national listing price rather than any single store. We record the price per bundle and convert it to a price per square at 3 bundles per square. We do not link to individual product listings because retailer URLs and prices change too often for a link to stay accurate; anyone can repeat the check by searching either retailer’s site for the product names on the manufacturer pages above.

3. Federal wage statistics

Used to check the labor share of published job costs and to understand how labor differs between states. Installed labor per square is not the same as a roofer’s wage: a contractor’s price includes crew size, insurance, equipment, overhead and margin. We use wage data as a sanity check on survey figures, not to build labor cost from scratch.

4. Published contractor cost surveys

These are the main input for the total-job ranges. Each survey uses its own roof size, material and method, so we never average them blindly. We note what each one measured, convert to a per-square figure where the survey states the roof size.

  • Cost vs. Value Report 2025, Roofing Replacement: Asphalt Shingles (Journal of Light Construction). A national job cost, updated June 2025, for a defined project: tear-off and replacement of 30 squares of asphalt shingles on a rectangular hip roof with new underlayment, drip edge and flashing, with regional breakdowns.
  • Fixr roof replacement cost guide. At the review date this showed a national range of $7,500 to $14,000, last updated February 4, 2026.
  • HomeGuide roof replacement cost guide. At the review date this showed $5,700 to $16,000 total, or $3 to $6 per square foot installed, dated November 7, 2025.
  • HomeGuide roof repair cost guide. Repair pricing by problem, by scale and by roof material, plus labor share and minimum call-out fees. Dated February 9, 2026 and checked September 10, 2026, when it showed $150 to $1,000 for a minor repair and $1,000 to $3,000 for a moderate one.
  • HomeGuide tile roof cost guide. Tile roof costs by material, style and roof size, the tile replacement cost breakdown and lifespan by tile material. Dated April 5, 2023 and checked September 15, 2026; its overall range matches the tile range in the roof replacement cost guide above. Added September 15, 2026.

5. Industry technical references

Used for installation conventions such as minimum pitch for shingles, underlayment requirements and waste allowances, not for prices.

6. Insurance regulators, statutes and consumer guides

Used for how homeowners insurance treats roofs: what is covered, replacement cost and actual cash value, deductibles, and state rules. Not used for prices. Where a rule is state law, the page names the state and links the statute. Added September 14, 2026.

7. Warranty terms and consumer guidance

Used for what shingle warranties cover, how non-prorated and prorated coverage work, registration and transfer. Not used for prices. Warranty terms change, so each page that uses them gives the date they were checked. Added September 15, 2026.

How a cost range is built

  1. Material per square. Retail price per bundle × 3, plus an allowance for underlayment, starter, ridge cap, drip edge and fasteners priced from the same retailers. This gives a low and high material figure per square depending on shingle grade.
  2. Installed cost per square. Taken from the published surveys, converted to per-square using the roof size each survey states. The spread between surveys becomes the low and high end of the range.
  3. Material share: not currently cross-checked. We would like to check the material figure from step 1 against the installed figure from step 2, but we cannot do that defensibly yet. Accessory pricing for underlayment, starter strip, ridge cap, drip edge and fasteners could not be verified from a citable public source, so we have no supportable figure for total material cost per square. What the survey data does show is the shingle-only share: HomeGuide puts roof materials at $100 to $250 per square against an installed total of $400 to $900 per square, which is about 25 to 28 percent. That covers shingles alone and excludes every accessory, so the true material share is higher by an amount we have not established. Until accessories can be priced from a source we can cite, we publish the shingle-only share, label it as such, and do not assert a total-material ratio.
  4. Rounding. Per-square figures are rounded to the nearest $5 and totals to the nearest $100. We publish ranges, not single numbers, because a single number would imply a precision the data does not have.

Every cost page lists the sources used for that page and carries its own “Last updated” date. Where a page gives a figure for a particular state, it is taken directly from a state-level source and the page names it; we do not scale national figures by state. State roofer wages come from the BLS May 2025 estimates, retrieved through the BLS public data API. The price-adjusted wages on that page divide those state wages by the BEA’s 2024 regional price parities.

How often figures are updated

  • Cost figures are reviewed periodically. Each cost page shows the date it was last reviewed.
  • A review is also triggered when the Producer Price Index for building materials moves noticeably, or when one of the surveys above publishes a new edition.
  • At each review, every source link on this page is re-checked. Sources that have gone offline or behind a paywall are removed rather than left as dead links.
  • Calculator formulas do not need updating. If an assumption such as bundles per square changes, the change is noted on the calculator page.

What the figures are not

  • Not a quote. Your price depends on your roof, your region, the season, the contractor and what they find when they tear off the old roof. Get at least three written estimates.
  • Not local. Unless a page says otherwise, figures are national. Labor and material costs in high-cost metro areas can sit well above the top of a national range.
  • Not expert opinion. Nobody here has installed a roof. The figures are researched from the sources above and the arithmetic is shown. Where a claim needs field judgment, such as whether a roof can be overlaid rather than torn off, the page says to ask a contractor.
  • Not influenced by advertisers. Quote request forms on the calculator pages connect homeowners to third-party contractor networks. Those partners do not supply, review or influence any figure published here.

Corrections

If you find a figure that does not match its source, a source that has changed, or a calculator result that looks wrong, use the contact page and include the page and the number. Corrections are made when a better public source exists, and the page’s review date is updated when they are.