Roofing Shingle Calculator

Order the Right Amount of Shingles the First Time

Roofing material lists are one of those things where a small measurement mistake turns into a big return trip to the supplier — or worse, a job that stalls halfway through because you're short a square of shingles. This calculator adds up multiple roof sections, adjusts for pitch if you measured the flat footprint instead of the slope, applies a waste factor for cuts and hips, and breaks everything down into bundles, squares, ridge cap, starter strip, underlayment, and nails — with an editable price per item so the final number reflects what you're actually paying.

How to use it

• Add a row for each distinct roof section or plane and enter its length and width — click "Add Roof Section" for hip roofs, dormers, or any roof with more than one rectangle to cover.
• Choose whether your measurements are the flat attic footprint (needs a pitch adjustment) or the actual roof surface measured along the slope.
• If using footprint measurements, pick your roof pitch (rise over 12) so the calculator can convert flat area into true sloped roof area.
• Set your shingle type, waste factor, and ridge/eave lengths, then open the pricing section to plug in real prices from your supplier for an accurate total.

Real-world use cases

Ordering shingles for a full re-roof and wanting a materials list before calling around for quotes, estimating a hip roof with several distinct sections that all need separate area calculations, double-checking a roofer's bundle count against your own numbers, or budgeting a DIY shed or garage roof from scratch.

Frequently asked questions

What's a "square" in roofing terms?

A square is simply 100 square feet of roof area — it's the standard unit roofers and shingle manufacturers use instead of raw square footage, which is why every bundle count in this calculator is built from the total number of squares.

Why does pitch matter if I already know my roof's footprint?

A steep roof has more actual surface area than its flat footprint suggests, because the slope stretches that area out. A 4/12 pitch adds about 5% more surface area than the footprint, while a 12/12 (45-degree) pitch adds over 40% — skip this adjustment and you'll come up noticeably short on material for anything steeper than a shallow slope.

How much waste factor should I actually use?

10% is a reasonable default for a simple rectangular roof with few cuts. Roofs with lots of hips, valleys, dormers, or an irregular shape should use 15-20% to cover the extra cutting and fitting waste around those features.

What's the difference between ridge cap and starter strip?

Ridge cap shingles cover the peaks and hips where two roof planes meet at the top, while starter strip shingles run along the eaves (the bottom edges) to give the first row of regular shingles a properly sealed base to lock into. Both are sold separately from your main field shingles, in their own bundles.

Do I need synthetic underlayment or felt, and does it change the roll count?

Either works, but they cover different areas per roll — traditional 15lb felt typically covers about 4 squares (400 sq ft) per roll, while many synthetic underlayments cover 10 squares or more. The underlayment coverage field is editable specifically so you can plug in the actual coverage printed on the product you're buying.