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Free Siding Calculator (+ Guide)

A free siding calculator that counts walls and gables, takes off windows and doors, and adds extra for cuts.

Navid Moazzezby Navid Moazzez·Updated 3. okt. 2026·2 min read·
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This free siding calculator works out how much siding a house takes, from its length, width and wall height, gables included.

It takes off the windows and doors, adds extra for cuts, and counts the boxes.

I built it because the gables are easy to forget, and they're where a siding order comes up short.

Here's the formula, a worked example, and the mistakes to avoid.

key_takeaways.mdTL;DR

Key takeaways

Wall area = 2 × (length + width) × wall height.
Each gable adds its width × its height ÷ 2.
Take off the windows and doors, then add extra for cuts.
A 50 by 30 foot house with 9-foot walls and 2 gables 6 feet high has 1,420 square feet to side: 1,562 with 10% extra.

What is a siding calculator?

A siding calculator turns a house's size into the siding to buy.

It counts the walls and the gables, and gives the total in square feet and squares of 100 square feet.

How siding is worked out

The walls make a band around the house. Each gable is a triangle on a short side.

Work out your siding0/4

A worked example

Here's the example the calculator loads: a 50 by 30 foot house, 9-foot walls, 2 gables 6 feet high, 200 square feet of windows and doors, 10% extra, and boxes of 200 square feet.

2 × (50 + 30) × 9 = 1,440 square feet of wall. The gables add 2 × 30 × 6 ÷ 2 = 180. Less 200, that's 1,420. With 10% extra, 1,562 square feet, or 8 boxes.

Mistakes to avoid

These are the slips that come up most.

  • Leaving out the gables
  • Taking off windows and doors twice
  • Ordering exactly the wall area, with nothing for cuts

Who is the siding calculator for?

It's for anyone residing a house or pricing a quote, and these tools help around it.

Count the gables, and the last wall won't come up short.

Plan your money with your AI

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Siding Calculator FAQs

Questions about the siding calculator? Here's what to know.

A siding calculator works out how much siding a house takes, gables included.

Multiply the perimeter by the wall height, add the gables, and take off windows and doors.

Multiply its width by its height and divide by 2.

Yes, take off what you won't side, then add extra for cuts.

A square is 100 square feet.

Divide the total by the coverage printed on the box, and round up.

Yes, switch to meters and the results show in square meters.

Yes, it's free with no sign-up.

It runs in your browser, and your numbers stay on your device.

I did.

I'm Navid Moazzez, and I made the siding calculator as one of my free tools on navid.me.

More about me.

Navid Moazzez

AI business strategist & AI OS builder

Navid Moazzez helps creators and founders master AI and build their own AI Operating System (AI OS) to automate their business and life.

Navid.me is reader-supported. When you buy through links on this site, I may earn an affiliate commission. Learn more.

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