How many squares of siding do I need?

Total wall area (including gables, ignoring small windows) × 1.10 ÷ 100, rounded up. A 1,500 sq ft single-storey house typically needs 15–20 squares.

Do I subtract windows and doors?

Most estimators do not subtract openings smaller than a garage door; the waste from cutting around them roughly equals their area. Subtract garage doors and large picture windows.

Starter strip, J-channel around openings, corner posts, house wrap and fasteners. The trim line is a rough perimeter figure; measure your openings for an order.

Siding calculator

Form 72 · Materials estimateFigures checked 2026-09-04

US customary

Measurements

Length(ft)

Width(ft)

Areas this size

What you need

Quantity · Amount

01Area to cover30 × 20 ft600 sq ft
02Siding to buyincluding 10 % waste660 sq ft
03Squares at 100 sq ft each$250 per square7 squares$1,750
04Starter strip and J-channel (approx.)rough perimeter allowance; measure your openings98 ft

Total, materials$1,750

The material

Waste allowance(%)Cuts around openings and corners; 10–15 %

Coverage per square(sq ft)One square = 100 sq ft; a box of vinyl usually holds two squares

Prices — put in what you were quoted

Price($ per square)Vinyl $150–350 per square material; fiber cement $300–600

Total, materials660 sq ft of siding$1,750

Where these figures come from

Square = 100 sq ft, the trade unit for siding and roofing.
Prices are typical US material-only figures at the date on this sheet; installed prices are per square foot.

Siding is sold by the square (100 sq ft). Add each wall as an area (length × height); for a gable end add a triangle as an extra area at half its height. The sheet adds 10 % for cuts and shows squares and cost.

Worked examples

Four walls 40 × 10 ft: 18 squares — squares at 100 sq ft each, about $4,500 in materials.
One 24 × 9 ft wall: 3 squares — squares at 100 sq ft each, about $750 in materials.

How it is worked out

Wall area × (1 + waste) = siding to buy. Squares = that ÷ 100, rounded up. Cost = squares × price per square.

The figures behind it

Square = 100 sq ft, the trade unit for siding and roofing.
Prices are typical US material-only figures at the date on this sheet; installed prices are per square foot.

Every figure here is an estimate. Materials vary with moisture, compaction and product; order a little extra and confirm quantities with your supplier.

Questions people ask

How many squares of siding do I need?: Total wall area (including gables, ignoring small windows) × 1.10 ÷ 100, rounded up. A 1,500 sq ft single-storey house typically needs 15–20 squares.
Do I subtract windows and doors?: Most estimators do not subtract openings smaller than a garage door; the waste from cutting around them roughly equals their area. Subtract garage doors and large picture windows.
What else do I need?: Starter strip, J-channel around openings, corner posts, house wrap and fasteners. The trim line is a rough perimeter figure; measure your openings for an order.

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