the rectangle formula will work with any variation of a rectangle.

Keep in mind that this method is the least accurate but, it's a quick way to get a "ball-park" idea of your exterior square footage.  Some houses are more and some are less but, for most houses this method works well.  This method has a variance of +/- 200 square feet in most cases and in rare cases +/- 500+ square feet.
* Please only use this method as a very general "idea" of your exterior square footage, never base any financial decisions off of this method.

1. Get your homes interior square footage (livable space.)
2. Add any other attached square footage (i.e.-an attached garage or unfinished room.)
3. You now have your homes "ball-park" exterior square footage.*

Our method for calculating your homes exterior square footage and generating estimates is: very fast, backed by 50+ years of experience, uses modern technology, is accurate down to the square inch & generates extremely detailed information about your homes exterior.  Although we at Exciting Home Exteriors exclusively own and use this system you can calculate your homes exterior square footage in the same detailed fashion as our system does.  Here's how:

How-To calculate your Homes Exterior Square Footage down to the Square Inch like Exciting Home Exteriors' does.

1. Use the detailed method explained above to get your homes "overall raw" exterior square footage with one difference - your measurements should be down to the fraction of an inch. (i.e.- 234 1/4 inches would be 234.25 inches)
2. Deduct anything that does not get siding. (i.e.- windows, doors, chimneys, brick work and the like.) Remember to keep your measurements down to the fraction of an inch.
3. You now have your homes "raw" exterior square footage.  This measurement is your homes exact exterior surface area down to the square inch.
4. Now you must calculate material waste.  This is where experience comes into play.  Different siding products have different waste percentages in relation to your homes exterior and that relation can and does vary from house to house.  But, that variation usually fluctuates from 10% to 15% (usually).  So a good number to use (again we are getting back to ball-park estimates) is 12.5%.  Example: if your raw exterior square footage is 1,500 square feet times 12.5% (.125) equals 187.5 square feet.  Now add that to your raw exterior square footage and you get 1,687.5 square feet.  Or you can skip a step and multiply your raw measurement by 112.5% (1,500 x 1.125 = 1,687.5).

This is a time consuming process to do long hand but it is very accurate.

Material Waste: A Closer Look

The factors involved in calculating material waste include: product coverage area, wall dimensions and applicator expertise.

Product Coverage Area: Let's look at an arbitrary siding panel.  It's dimensions are 11.5 inches tall by 144 inches long.  We are going to use a 1.5 inch overlap so, now the coverage area of the panel is now 10 inches.  To get the coverage area of the individual siding panel (uncut) is 10 inches times 144 inches which equals 1,440 square inches.  But we need square feet so we must convert the square inches to square feet.  To accomplish this we simply find a common ground between the two.  Let's take a single square foot (1 foot x 1 foot = 1 square foot) also there are 12 inches to one foot so we will substitute feet for inches to get our common ground ( 12 inches x 12 inches = 144 square inches.)  So our common ground is 1 square foot (1sq') equals 144 square inches (144sq").  Looking back at our arbitrary siding panel, 1,440 ÷ 144 = 10sq'. Now you know how to calculate a panels coverage area.
       Some products will generate more unusable waste than others.  For example, if a wall is 101.5 inches tall and a siding products coverage area height is 10 inches, 101.5 ÷ 10 =  10.15, so that's 10.15 panels high but only .15 or 1 1/2 inches of the last panel is used.  So that's 8 1/2 inches wasted on the last panel, or 85% of the siding panel wasted, if you only accounted for 12.5% over-all you will come up short on your siding product and have to pay for more.  For some products, if there are an adequate amount of small areas or usable areas on a home a lot of the waste can be used in those areas.  Again this is something you only really learn from experience.

Wall Dimensions: Sometimes the products selected just don't match the walls to be covered and a lot of waste is generated.  If you don't have a plan on how to utilize your waste ahead of time you could get stuck with a lot of cut-up product which cannot be returned for credit.  Ok, so your thinking I'll just get a whole lot of product and return what I don't use.  If you do this make sure you understand if you can return the product to the supplier and if they charge a restocking fee (most do and it's around $10 to $20 per $100 lost to a restocking fee.)  Also, having too much extra product on a job site tends to get damaged.

Applicator Expertise: As you can imagine, if the applicator doesn't know what he/she is doing he/she will waste a lot of material by miss cutting it.  Also, a skilled applicator will utilize waste by installing siding on the waste generating walls first, then using that waste on other walls.  Our applicators and our owners (who are applicators themselves) have done entire siding jobs and produced such minimal waste that it fit into a single garbage can.  This amount of waste generation is rare but, for a skilled applicator who uses their head and keeps waste in mind, product efficiency is a natural outcome.

Few things frustrate a siding applicator more than a shortage of materials on a job site.  Also, not accounting for material waste appropriately can really increase the material costs on a job.  We wish you the best on your project!