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Roofing Shingle Calculator

Roof area to squares, bundles and ridge cap.

Also known as roof square calculator · roofing squares · shingle squares

Quick answer

With the default inputs: Roof area 1500 ft² · Shingle type Architectural · Ridge and hip length 60 ft etc.Roofing squares 16.5 sq

Use your own dimensions ↓

Inputs

ft²
ft

Result

Roofing squares
16.5sq
Area with waste1650ft²
Shingle typeArchitectural
Shingle bundles50bundles
Ridge cap bundles2bundles
Starter course (est.)156ft
Weight per bundle78lb
Weight per area2.4lb/ft²
Total weight3960lb
Short tons1.98ton
How this is worked out

One square is 100 ft², the only unit roofing is priced in. Both 3-tab and architectural run three bundles to the square - same count, but architectural bundles are heavier (75-80 lb) and expose less, so the two are not interchangeable. The tool estimates weight at 2.2 lb/ft² for 3-tab and 2.4 lb/ft² for architectural, with bundles held at the nominal three to the square - same bundle count, different tonnage, and hauling and roof-loading labour both follow the weight, so pricing architectural at the 3-tab density under-orders by about a tenth. Order against the manufacturer coverage figure, since exposure varies by product. Waste follows the shape: 10% for a simple gable, 15% with hips or skylights, 20% on complex or steep roofs with lots of cutting. Starter strip goes along the eaves under the first course and is usually measured from eave length - the perimeter figure here is an approximation, so scale it off the drawing. Skipping starter is why the first course lifts in wind, the most common starting point for storm damage. Ridge cap runs about 35 ft to the bundle, and more hips means more bundles.

Next up: Skirting Board Calculator · Plasterboard Quantity Calculator

Formula

1 square = 100 ft²the roofing unit
Squares = area × (1+waste) ÷ 100
Bundles = squares × 3same for 3-tab and architectural
Ridge cap = ridge length ÷ 35about 35 ft per bundle
1500 ft² gable roof in architectural shingles with 60 ft of ridge and 10% waste: 1650 ft² = 16.5 squares, 50 bundles of shingle and 2 bundles of ridge cap (60/35 = 1.7, rounded up). Total weight about 3630 lb, close to 1.8 tons.

How to work it out

  1. Work out roof area: projected area times the slope factor (1.054 at 4/12, 1.118 at 6/12, 1.202 at 8/12), plus 5-10% for hips.
  2. Divide by 100 for squares - the only unit roofing is sold in.
  3. Bundles = squares x 3, the same for 3-tab and architectural.
  4. Ridge cap is ridge length ÷ 35, and more hips means more bundles.
  5. Waste follows the shape: 10% simple gable, 15% with hips or skylights, 20% complex or steep.

Where it goes wrong

Material and cost

Architectural shingles run USD 90-140 per square in material, with 3-tab cheaper at 70-100. Tear-off is 50-100 per square and installation labour 100-200 per square. A full re-roof including strip, underlayment, shingles and ridge cap commonly lands at 350-550 per square, so a 1500 ft² roof is roughly 5000-8000.

On site

Basis

FAQ

How do I work out roof area?
Not from the footprint. For a gable, multiply projected area by the slope factor: 1.054 at 4/12, 1.118 at 6/12, 1.202 at 8/12 and 1.414 at 12/12. Hip roofs need another 5-10% for the extra hips. The reliable route is to measure the length and the raking length of one slope and multiply.
Why 10-20% waste?
Shingles come in fixed widths, so eaves, rakes and hips all need cuts that leave half or most of a shingle unusable. A simple gable only cuts two rakes, so 10% does it; a hip roof cuts along every hip, so take 15%; skylights, dormers and chimneys push it to 20%. Better two extra bundles than a top-up from a different production run with a visible colour difference.
Do I have to strip the old shingles?
Up to two layers can go over the old roof in many jurisdictions, provided the existing surface is flat and sound. It saves tear-off and dumpster costs, but doubles the weight, shows imperfections and guarantees a full strip next time. It also voids the manufacturer warranty - a 25 or 30 year warranty requires stripping back to the deck.

Cite this page

Use this format in reports, method statements or coursework. The link is permanent.

Building Calculator. Roofing Shingle Calculator. 2026-10-25. https://jianzhujisuan.com/en/roofing-squares

Results are estimating aids only and are not a design basis. Construction and final accounts must follow the drawings, the applicable standards and an approved method statement. Anything affecting structural safety, shoring or falsework must be checked by a suitably qualified engineer.