About

What we do

Homeowners and contractors use our tools to turn a few measurements into numbers they can act on: a roof’s pitch, how many bundles of shingles to order, how many posts and bags of concrete a fence needs, or how many boards cover a deck.

• Roof Pitch Calculator — Pitch, angle, slope % and rafter multiplier from rise and run.
• Roofing Materials Calculator — Squares, bundles, underlayment and drip edge.
• Fence Calculator — Posts, rails, pickets and concrete for any run length.
• Deck Calculator — Boards, joists and screws for a rectangular deck.

How we work

Every calculator shows its formula and the assumptions behind it, cites the codes and product data it relies on, and is covered by automated tests. Calculations run in your browser; nothing you type is sent to us or stored. See the methodology for details.

Who is behind ExteriorMath

ExteriorMath is owned by Sawera Nadeem. The calculators and content are built and maintained by Salman Ahmed.

The formulas are based on published building codes, industry manuals and manufacturer data, including:

• International Code Council, International Residential Code: R905 (roofing) and R507 (decks).
• National Roofing Contractors Association, The NRCA Roofing Manual: Steep-slope Roof Systems.
• U.S. OSHA, 29 CFR 1926.501(b)(13), fall protection in residential construction.
• Manufacturer product data for shingle bundle coverage, underlayment roll coverage and concrete mix yield.

The full list of formulas, assumptions and sources is on the methodology page.

Spotted an error?

If a result looks wrong, please tell us through the contact page. Include the Share link from the calculator so we can check your exact inputs. We correct the tool and its tests when we find a mistake.

Estimates, not quotes

Results are planning estimates. Always confirm quantities with your supplier, follow the manufacturer’s instructions and check your local building code before you buy or build.