Drywall installation or repair costs can go through the roof if you don’t know what is required from the word go.

On average, you will need roughly 20 drywall sheets (standard 4 x 8 ft) for a 12 x 12 room. The total cost to purchase all the drywall sheets for a 12 by 12 room is roughly $300.

This quick and easy guide covers materials and installation costs to install drywall on standard 12 x 12 rooms.

Compare Drywall Quantities Needed for Standard Room Sizes

To help you estimate *costs, here is a breakdown of the quantities or sizes of drywall you will need for common/standard room sizes in the United States.

Room SizeQuantity (Total Number of Sheets)Average Cost (4x8 sheets)
10 by 10 room14- 15$225
12 by 12 room17- 20$300
14 by 12 room21- 24$360
16 by 16 room25- 28$420
20 by 20 room32- 35$525

Note *: The costs are based on current market rates and may be slightly different depending on when you make your purchase, where you buy the drywall sheets and the type of drywall.

Expert Tip: Please use the free installer finder tool at the top of this page to get more up-to-date quotes when you are ready to install or repair drywall. We’ll recommend at least three top-rated drywall experts or companies near you who’ll advise you on costs.

How Do I Calculate How Much Drywall I Need?

Consider the following things when calculating how much drywall you will need. Drywall is sold in standard sheets so it can be easy to estimate quantities if you know what to look for.


Size of your room

Room size is the most important factor when estimating how much drywall and other materials you need. You need to measure the surface area where the drywall will be installed to have a clear picture of the number of sheets and probably other materials (like drywall mud) needed.

You need to have the following measurements for the room where the drywall will be installed for a proper estimate:

  • Height of the walls- floor to ceiling
  • The perimeter of the room
  • Ceiling surface area
  • Size of single drywall sheet- most sheets come as 4 x 8 standard but you can go for other sizes if you need to.
  • Waste adjustment- this will depend on your installation and the shape of your room.

Once you have all these measurements, then you can calculate the exact number of sheets you need using this formula:

Number of drywall sheets= ((room perimeter x Wall height + Ceiling surface area x)/drywall sheet size) + waste adjustment
Other factors to consider include:


Number and size of windows and doors

How many windows and doors does the room have? Measure their dimensions and factor them into your calculations when getting the perimeter to get an accurate figure. You won’t be installing drywall on the windows or doors.

We always advise that you get a drywall expert near you to do the measurements and give estimates before you purchase the materials. This will save you money and time in the long run and you won’t have to worry about making errors or wastage.


Type and size of drywall sheets

There are several types of drywall sheets in the market. Some drywall sheets are moisture-resistant while others are mold-resistant. More importantly, the size of the drywall sheets matters since you will most likely have several options when you go shopping.

We recommend standard 4 by 8 drywall sheets for rectangular 12 x 12 rooms as the best value for money but you can also purchase the following readily available sizes if they suit your needs better:

Medium 4 by 10 sheets- These are medium-sized sheets good for any project where the standard 2 by 8 sheets are not large enough to fit properly based on the shape of your wall or ceiling.

Large 4 by 12 sheets – These are long vertical sheets perfect for tall walls or high ceiling rooms.

Extra-large 4 by 16 sheets- Sometimes you may need these tall drywall sheets if you have tall walls and need to install the sheets unbroken from top to bottom. Keep in mind that tall drywall sheets may be harder to install especially if you are on your own.

Drywall also comes in different thicknesses with the thickest ones being the most expensive and the thin ones being the least expensive. You will likely be installing half-inch sheets for most rooms because it is the standard size unless you are looking for extra insulation. Other common sizes are ¼ inch and 5/8 inch thick.

How Many Square Feet Are in A 12-Foot Sheet of Drywall?

The slightly large 4 by 12 sheet of drywall covers 48 square feet of space on your wall or ceiling. The standard 4 by 8 sheets of drywall will cover 32 square feet of space on your wall. Using this as a reference, you will need between 17 to 20 sheets of standard 4 by 8 drywall sheets for a 12 by 12 room with windows and doors factored into the formula.


Expect to spend an average of $2 to $4 per square foot to have drywall installed depending on the availability of labor in your location and other installation factors. This translates to a total amount between $300 to $500 for a 12 by 12 room.

Some drywall installers charge an hourly rate for their labor usually between $50 to $120 per hour so your costs might be slightly different.

Tip: We recommend you negotiate a rate based on the surface area in square feet be worked on as opposed to an hourly rate If possible. This way you will have more control over the total cost of the installation as you already know your room measurements.

Buy at least 26 pounds of drywall mud if you are installing drywall on a 12 by 12 room. You need approximately 0.052 pounds of drywall for a square foot. With drywall mud, more is always better because there will always be imperfections to fix. You will also need the leftover mud to fix holes in the future.

How Much Drywall Mud Do I Need for A 12 X 12 Room

Benjamin McInerny
Author: Benjamin McInerny - is a qualified arborist with 20 years of industry experience. Ben has a wide knowledge of renovation and DIY projects around the house such as lawns, fencing and painting. Ben shares his skills with DIY and gardening enthusiasts.