How Many Squares of Shingles Do You Need?

Every roofer knows the pain of quoting a job from memory and eating the overage later. The difference between a solid estimate and a money-losing one usually comes down to one number: accurate squares.

What is a "square" in roofing?

A square is 100 square feet of roof surface. It is the industry-standard unit for buying shingles, underlayment, and labor. When a supplier asks how many squares you need, they mean how many 100 sq ft units the installed surface covers.

Tip: never confuse ground footprint with roof surface. A 6/12 pitch roof has roughly 12% more surface area than its footprint. Pitch is where most first-time estimators lose money.

Measuring the roof without climbing it

You can get the true tilt-adjusted surface area without a tape measure. A satellite measurement of the property returns the roof area accounting for pitch — not the flat footprint. That number is what you should base square counts on.

To convert to squares:

• Roof surface in sq ft ÷ 100 = raw squares
• Multiply by your waste factor to get orderable squares

The waste factor: simple vs complex

Roof complexity drives how much shingle you throw away at hips, valleys, and rakes:

• Simple gable — 10% waste
• Moderate hip/valley — 15% waste
• Complex cut-up — 20% waste

A cut-up roof with several valleys genuinely skips 15-20% of its shingle material to cuts. Skimping on waste to win a quote is how you turn a "good" job into a break-even one.

A worked example

Suppose satellite shows a 2,450 sq ft roof surface on a moderate hip roof:

1. Raw squares: 24.5
2. Waste at 15%: 24.5 × 1.15 = 28.2 orderable squares
3. Shingles at 3 bundles/square: 28.2 × 3 ≈ 85 bundles

That single waste adjustment is the difference between ordering 74 bundles and 85 — a difference of roughly $576 in material at $52 a bundle.

The bottom line

Count squares from a true surface measurement, apply a honest waste factor for the roof shape, and always round up on shingles. Under-ordering saves a little cash today and costs a full re-order (and a schedule delay) tomorrow.

RoofHQ measures the true surface area and applies your chosen waste factor automatically — so your material list is ready to send to the supplier the moment you quote.