# How to Calculate Drywall for Any House or Office Project

To calculate how much drywall is required for renovation or construction project you need to divide entire surface area of walls and ceiling by size of drywall sheet.

Easier said than done and in this topic Remodel On Point can teach you simple ways how to calculate drywall and what types of material used in different rooms or areas.

(Length of Walls  X  Height  +  Ceiling Area)  /  Drywall Sheet Size

Let’s not rush into this and make tons mistakes. The idea is to break it down so everyone can understand formula and follow it along.

• Drywall size
• Calculate Walls
• Calculate ceilings
• Do the math and add extras

In Example described below, 3000 square foot home requires 315 pieces of 4×8 drywall. 298 of them are regular drywall sheets, 13 green boards for bathrooms and 4 dense boards for gas fireplace.

Drywall size

We are going to make it simple and start with most popular drywall sheet size – 8ft x 4 ft. Professionals like to mix all drywall sizes and use where appropriate.

For examples on ceilings of large rooms and open areas installers like 4 x 12 size. Rooms where drywall can be secured in stand up position it’s better to match the size of room height.

All other rooms are just a preference of drywall installers. It can be 8, 9, 10 or 12 foot long drywall boards. For our example we will just use 8 x 4 sheets which gives us 32 square feet of drywall coverage.

Calculate Walls

The longest process is measuring every wall of the house. Deferent height of walls on each floor makes it ever harder.

We are talking about literally every wall. Every room has to be measured throughout. Very often people forget to measure inside of closets, near stairs, behind cabinets and installed fixtures.

In our example house we have 1500 square feet on main floor that is 10 feet high, and same size second floor with 9 foot ceiling. Don’t mix square footage with size of walls.

It takes up 30-45 minutes to measure walls. Main floor is mostly open and we have 240 linear feet times 10 foot height = 2400 sq ft.

Second floor has all the bedrooms, bathrooms and closets. Our average home has 520 linear feet of walls multiplied by 9 feet equals to 4680 sq ft.

Calculate ceilings

Technically there is no need to calculate ceiling surface if you know the size of house. Ceiling equals to square footage of floor area.

Because we assumed our example house is 3000 sq ft, than our ceiling surface area is 3000 sq ft.

Do the math and add extras

Not that we have all the numbers it’s as easy as adding them together and finalizing count. We got 3000 sq ft on ceiling, 2400 sq ft on all walls of main floor and 4680 sq ft on second.

3000 + 2400 + 4680 = 10080 sq ft – Full House interior surface area.

As we mentioned before, it is to be divided by size of drywall we want to use.

10080 / 32 = 315 –  Drywall Sheets

This is not over! Keep reading further details that we recommend including before making a final order.

## Types of Drywall Needed for Each Area

Drywall is construction material made of gypsum and it works well for interior surface area. Its’ main purpose to cover open walls with rough ins as well as make perfectly smooth wall.

Drywall is not flammable and is considered to be one of the best materials for renovation projects. Besides variety of sizes it has several types.

### Green Boards

Best installed in wet and humid areas of the house. This drywall has some resistance to moisture but is does not serve as waterproofing wall.

Recommended area for installation: bathrooms, laundry, utility room, indoor pool area, humid basements.

### Fire Rated (type X)

With bylaws and building code improving every year, now we can create better fire protection for occupants. Drywall material was adjusted to have fire rating purpose.

Recommended area for installation: walls of house close to neighbor, commercial properties with multiple units, households split or design for multifamily occupancy.

### Dense Boards

Regular fire rated drywall is not enough when there is wanted source of heat in the house and we want to keep it. Dense boards have much better purpose on fireplaces and similar heat projecting appliances.

Recommended area for installation: gas or wood burning fireplace.

### Soundproof Quite Rock

Now we can insulate rooms or specific parts of building. Before it could only be done with sound rated insulation but not long ago soundproof drywall made it easy. The cost of it can be 5 – 8 times higher than regular drywall.

Recommended area for installation: between floors, home studio, dental or medical office.

## Do You Need to Subtract for Windows and Doors?

After calculating length of each interior and exterior wall of the house and finalizing math we need to make sure everything is don’t by the book. The question we often hear is do you need to subtract material for windows and door openings?

It gets slightly complicated and there is not straight answer. If the house has 10-20 doors and regular or small size windows than don’t even bother.

Modern homes with floor to ceiling windows is a different story. Imagine full real wall of windows and patio door. Just measure largest windows or doors and subtract them from final formula.

Don’t forget to order a little extra material. Drywall does not need high percentage of waste to be included in purchase. We estimate that 5% of extra sheets would be enough for professional drywall installed, because don’t know how to cut and place boards without much waste.

## Average Amount of Drywall Needed for House

This is not how drywall is calculated and we provide average material only for comparison or educational purpose.

Our team calculated drywall for 10 different houses and came up with average number of sheets required for installation. The magic number we got is 3.6. Meaning on average we would multiply square footage or size of home by 3.6 to get surface area of drywall.  For example for every 1000 sq ft of home we got 3600 square feet of drywall or just over 112 regular size sheets.

Steven H.
General Contractor and Home Builder with over 20 years of experience. Write and Edit educational posts for several Remodeling Blogs. Specialize in trade management and technical construction details.