Siding answer guide

How much siding do I need?

Estimate siding quantity from wall area, openings, gables, waste, siding squares, trim allowance, material cost, and labor planning.

Reviewed - May 26, 2026

Short answer

Measure the gross wall area, subtract window and door openings, add waste for cuts and layout loss, then divide by 100 sq ft per siding square.

For a 160 linear ft house perimeter with 9 ft walls, 180 sq ft of openings, and 10% waste, the calculator estimates 13.9 siding squares.

If you measure wall elevations instead, include rectangular wall sections and triangular gables before subtracting openings; the sample walls-plus-gables takeoff below estimates 14.0 siding squares.

Use the siding calculator

Siding quantity method

Choose a measurement method: perimeter x average wall height, wall-by-wall rectangles plus gables, or a known net siding area.
Subtract the combined window and door area when openings have not already been deducted.
If you use known area mode, confirm the square footage is net of openings before adding waste.
Add waste for cuts, laps, corners, gables, trim detail, and layout loss.
Divide the order area by 100 sq ft to convert siding area into siding squares.
Use the same net wall area to estimate housewrap, trim, starter, fastener, material, and labor allowances.

Quick examples

120 linear ft perimeter

9.1 squares

8 ft walls, 140 sq ft openings, 10% waste

160 linear ft perimeter

13.9 squares

9 ft walls, 180 sq ft openings, 10% waste

Walls plus two gables

14.0 squares

40x28 ft shell, two 8 ft gables, 180 sq ft openings

1,500 sq ft known area

16.5 squares

Known net siding area, 10% waste

1,500 sq ft with higher waste

17.3 squares

Known net siding area, 15% waste

These generated examples use perimeter, wall-by-wall, and known-area modes with the current U.S. default siding assumption of 100 sq ft per siding square.

Worked example

160 linear ft perimeter with 9 ft walls.

Siding quantity

13.9 squares

1,386 sq ft order area including 10% waste

Net wall area

1,260 sq ft

180 sq ft openings deducted

Measured wall area

1,440 sq ft

160 linear ft x 9 ft average wall height

DIY material total

$3,717–$11,088

Siding, housewrap, trim, starter, and fastener allowance

Contractor total

$6,741–$18,018

Materials plus labor

Starter shopping list

vinyl siding 13.9 squares
Housewrap, starter strips, corners, trim, fasteners Allowance included
Caulk and flashing tape As needed

This example is generated from the same calculator logic used on the Siding calculator page.

Measurement method

Perimeter mode works for early planning when wall height is fairly consistent around the house.
Use walls plus gables when the elevations have gable triangles, additions, uneven wall lengths, or partial siding scope.

Openings and waste

Deduct windows and doors as one combined area, but keep waste conservative because cuts around openings and corners create layout loss.
Known area mode should use net siding area after openings are already deducted, then add waste only once.

Cost planning

Material choice changes both siding cost and labor range, so vinyl, fiber cement, engineered wood, and wood should not share one installed price.
Plan removal, sheathing repair, flashing, water-resistive barrier details, trim package, story height, and access separately from the basic siding square count.

Ordering and quote scope

Track gross wall area, net wall area, waste-adjusted order area, and siding squares separately so quotes can be compared on the same basis.
Keep field siding, trim boards, starter strips, corners, j-channel, flashing, housewrap, and fasteners as separate scope checks even when allowances are included.

Common mistakes

Using floor area or house footprint as siding area.
Forgetting gables, dormers, wall jogs, corners, trim, and partial elevations.
Adding waste before subtracting openings, or subtracting openings a second time from a known net siding area.
Subtracting openings and then using a waste percentage that is too small for cut-up walls.
Treating siding material cost as the full installed project cost.
Ignoring removal, sheathing repair, flashing, housewrap, tall access, and local labor conditions.

FAQ

How do I calculate how much siding I need?

Calculate gross wall area, subtract window and door openings, add waste, then divide the order area by 100 sq ft per siding square.

What is a siding square?

A siding square is 100 sq ft of siding area. The calculator divides waste-adjusted order area by 100 and rounds up to the next tenth of a square for planning.

Should I subtract windows and doors from siding area?

Yes, subtract a combined opening area when you are estimating from perimeter or wall-by-wall measurements. If you enter known net siding area, openings should already be deducted.

How much extra siding should I order for waste?

Many early estimates use around 10% waste, with more for gables, corners, short runs, diagonal cuts, repairs, or complex elevations. The calculator lets you adjust the waste percentage.

How much siding do I need for 1,500 sq ft of net wall area?

With known area mode, 1,500 sq ft of net siding area and 10% waste generates 1,650 sq ft of order area, or 16.5 siding squares. At 15% waste, it generates 1,725 sq ft of order area, or 17.3 siding squares.

Does siding quantity include trim and housewrap?

The siding square count covers siding area. The generated cost estimate includes a planning allowance for housewrap, starter strips, corners, trim, and fasteners, but detailed trim packages should be checked separately.