ShingleTallySquares, bundles and everything else a roof needs, counted properly.

Shingles for a 48 × 50 ft roof at 5/12, complex

Shingles
94bundles
31.2 squares for a 48 × 50 ft footprint at 5/12 — complex / cut-up, 20% waste
Footprint48 ft50 ft2,400 ft²×1.0832,600 ft²of actual roof31.2 squares94 bundles · 20% waste+2 squaresthat footprint alone misses
Bundles3 per square94bundles
Squares (with waste)31.2sq
Roof area2,400 ft² footprint × 1.083 pitch factor2,600ft²
Pitch factor√(1 + (5/12)²) — pure geometry1.083
Waste allowancevalleys, dormers and changes of plane all waste material20%
Starter shingles196 ft of eave and rake2bundles
Hip & ridge cap102 ft of ridge and hips6bundles
Underlaymentsynthetic, 10 squares per roll4rolls
Ice & water shieldeaves, 24″ inside the exterior wall line — check if your code requires it637ft²
Roofing nails — standard4 per shingle, about 9,984 nails72lb
Roofing nails — high wind6 per shingle — required in high-wind zones and by most warranties above 110 mph107lb
Walkable5/12 can normally be walkedYes, with care
Footprint width
48 ft
Footprint length
50 ft
Pitch
5 /12
Roof type
complex

Footprint is not roof area

This is where roofing estimates go wrong, and they go wrong in the direction that leaves you short on a Saturday.

A 48 × 50 ft footprint is 2,400 ft² on the ground. At 5/12 the roof over it is 2,600 ft² — the pitch factor is 1.083, which is √(1 + (5/12)²). Pure geometry, no fudge factor.

Order off the footprint and you are 2 squares short before waste is even counted.

Squares and bundles

31.2 squares with 20% waste for a complex roof — 94 bundles at three per square.

Waste is not one number. A simple gable cuts only at the rakes. A hip roof cuts along every hip. A cut-up roof with valleys and dormers throws away a fifth of what you buy, and no amount of careful planning changes that.

The two lines everyone forgets

Starter: 2 bundles for 196 ft of eave and rake. Hip and ridge cap: 6 bundles for 102 ft.

These are separate products, not field shingles cut down. Using field shingles as starter voids most manufacturers' wind warranties, which is discovered at the claim rather than at the purchase.

Underneath

4 rolls of synthetic underlayment, and 637 ft² of ice-and-water shield at the eaves — 24 inches inside the exterior wall line, which is what the IRC asks for where it applies. Check whether your jurisdiction requires it.

72 lb of roofing nails at four per shingle, or lb at six for a high-wind zone.

Two things to price before you decide it is DIY

Tear-off: about 8,580 lb of old shingle to strip and skip.

And access. Above 8/12 a roof stops being walkable for most people, and roof jacks, planks or scaffolding cost real money that belongs in the estimate before you decide this is a DIY job.

Notes

  • **Footprint is not roof area, and the gap is bigger than people expect.** A 48 × 50 ft footprint is 2,400 ft² on the ground but **2,600 ft²** of roof at 5/12. Ordering off the footprint leaves you 2 squares short — and that is before waste.
  • The pitch factor is √(1 + (rise/12)²). There is no estimate in it and no manufacturer fudge — it is the hypotenuse. 5/12 gives 1.083.
  • 20% waste for a complex / cut-up roof: valleys, dormers and changes of plane all waste material. A simple gable wastes least because the only cuts are at the rakes; every hip and valley adds a run of angled cuts that produce offcuts nothing else uses.
  • Starter and cap are separate purchases, and they are the two lines that get left off estimates. 2 bundles of starter for 196 ft of eave and rake, 6 bundles of hip and ridge for 102 ft. Using field shingles as starter voids most manufacturer wind warranties.
  • At 5/12 the roof is walkable with proper footwear and a harness. Steeper than 8/12 and you are into staging.
  • Tear-off is the other half of the job. A single layer of asphalt shingle weighs 200–350 lb per square, so this roof carries about 8,580 lb of old material to remove and skip.

Nearby sizes

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