Room length
ft
Room width
ft
Room height
ft
Area under sloped walls
Number of triangular spaces
Base of triangular space
ft
Height of triangular space
ft
Total area under sloped walls
ft²
Room surface area
Include ceiling?
yes
Gross room area
ft²
Doors
Door height
in
Door width
in
Number of doors
Total doors area
ft²
Windows
Windows height
in
Windows width
in
Number of windows
Total windows area
ft²
Drywall amount
Net room area
ft²
Drywall panel type
Select...
Cost per panel
$
Number of panels
Total cost
$

The drywall calculator, alternatively called the sheetrock calculator, is a handy tool for determining how much drywall sheets do you need to cover all walls (and the ceiling) in your room. Drywall estimator can be used together with our paint and wallpaper calculators to finish the interiors of your house. Input your drywall measurements, quickly estimate the number of sheetrock panels you have to buy and make sure to never overspend on drywall again!

In the text below, we answer the question what is drywall, and tell you what different types of drywall you can find in your home depot, as well as what sheetrock prices to expect. Furthermore, you will learn about available drywall sizes and thicknesses. Finally, we are going to make sure that you won’t forget to prepare necessary drywall tools before you start drywalling.

What is drywall (sheetrock)?

Drywall is a construction material that also has other names: plasterboard, wallboard, gypsum panel, sheetrock, or gypsum board. The current version of gypsum board was developed in the first half of 20th century. Its popularity rose during the World War II. In those times the costs of building were very high, and there was a significant lack of qualified workforce. On the contrary, drywall had a low price and was easy to install even in a DIY setting.

A drywall sheet is a panel made of gypsum (calcium sulfate dihydrate) compressed between two thick sheets of paper. If we add certain materials to the gypsum mixture, we can improve the drywall resistance against humidity, water, mold, sound, or even fire. Drywall is often used to make interior walls or ceilings, as well as, surfacing already existing brick or cement walls.

Drywall is an excellent alternative to plaster because it does not require drying - if you have some experience, you can easily finish drywalling the entire house in just a few days. In fact, it is the current standard to finish homes with drywall. Installation is straightforward: all you have to do is to cut it to an appropriate size and then nail or screw it in place. Furthermore, even when it gets damaged or dirty, all you have to do is replace the faulty sheet with a new one. It is as easy as it sounds.

Remember that basic types of drywall are not water resistant. Do not use them in kitchen or bathroom, as the moisture will cause them to soften and eventually turn into a gooey paste quickly. A water-resistant type of drywall, cement board or tiles should be used in these rooms instead.

Types of drywall sheets

There are several types of drywall. They differ from each other with the additional materials used in their production, as well as, their function. Here we present the list of different types of drywall:

  • Regular drywall – it is white and available in many sizes from rather thin (1/4" or 6.5 mm) to thick (3/4” or 20 mm). Go to the drywall sizes and drywall thickness paragraph for more details.
  • Greenboard drywall – you can recognize it by its green paper covering. The covering was augmented with water-repellent substances. This type of drywall costs more but does not soften when exposed to humid conditions. It is a natural choice for rooms where there is a high moisture level, for example, a kitchen.
  • Blueboard drywall – it is similar to the greenboard drywall but it is also resistant to mold, and its covering has a distinguishable blue color. As you may think, it’s also more expensive than its green counterpart.
  • Soundproof drywall – it is enhanced with sound-absorbing materials such as damping polymers
  • Fire-resistant drywall (type X and C) – go to the next paragraph: drywall that will save you from fire to see more details.

Aside from different types of drywall, you can also find some drywall alternatives. In the bathroom, you could use tiles and cement board. Cement board is made of cement and reinforcing fibers. It comes in sheets, similar in shapes and thickness to drywall sheets, and may be laid by itself or as a basis for tiles.

Drywall that will save you from fire

If we check the chemical formula of gypsum that forms the core of drywall sheet we will see that it contains high percentage of water: Ca₂SO₄ * 2 H₂O. It's quite surprising, isn’t it? When the drywall is exposed to fire, the water in gypsum becomes free and evaporates. The rest that is left is the calcium sulfate: Ca₂SO₄. This process is called calcination, and it consumes vast amounts of energy. Because of that, it takes some time for the fire to break through the drywall layer.

As you can see, the drywall is fairly fire-resistant by itself. But some methods can enhance its fire-holding abilities even more. Apart from laying multiple layers of drywall sheets or using thicker drywall, you can buy special fire-resistant drywall. Type X drywall contains glass fibers that prevent drywall from cracking as the water inside gypsum evaporates. Type C is enhanced with the same glass fibers as type X but also contains the vermiculite. This substance expands (increasing its volume while decreasing density) when exposed to high temperature and fulfills emerging cracks in drywall.

It is worth considering drywalling the wall separating your house and garage with fire-resistant drywall. It is a good investment in the safety of your family.

Drywall sizes and drywall thickness

The most common drywall sizes in US are:

  • 4’ x 8’
  • 4’ x 9’
  • 4’ x 10’
  • 4’ x 12’

In other countries we can find drywall in sizes more adequate to SI units:

  • 1200 x 600 mm
  • 1200 x 2000 mm
  • 1200 x 2600 mm
  • 1200 x 3000 mm

You will finish your project more quickly with bigger drywall size as one sheet will cover more significant square footage of your wall. However, big sheetrock sheets are also more difficult to handle because of their weight and low maneuverability. Smaller drywall sizes are more comfortable to operate on and should be chosen for drywalling little rooms and areas.

There are several drywall thicknesses available. 1/4” and 3/8” (6.5 mm) thick panels are good for renovating ceilings and curved areas. 1/2” (12.5 mm) thick sheetrock sheets are the most common and are a perfect choice for standard walls. Thicker drywall sheets (more than 5/8” or 15 mm) should be used in walls that we want to be sound- or fire-proof.

How much is a sheet of drywall? - Sheetrock prices in US

Sheetrock prices typically range from 6$ to 15$ and depend on their size:

  • 4’ x 8’ drywall sheets cost from 6$ to 8$
  • 4’ x 9’ drywall sheets cost from 9$ to 11$
  • 4’ x 10’ drywall sheets cost from 10$ to 12$
  • 4’ x 12’ drywall sheets cost from 10$ to 14$

Naturally, if you want to use a thicker drywall, you will also have to pay more. Special usage sheetrock prices are also higher. It is the price for enhanced durability or functionality: resilience from water, noise, or fire.

Are you ready for drywalling? Drywall tools and materials

Here, we provide you with the list of necessary drywall tools and materials. Make yourself sure that you will not forget anything.

  • Drywall mud – it is a common name of the joint compound. With drywall mud, you will be able to join sheets of drywall and cover any holes. It comes in different volumes and three versions: dry, premixed, and low-dust. Dry joint compound is cheaper than its premixed counterpart, but you have to do the mixing with water by yourself. Be careful! It is not easy to add ingredients preserving the correct ratio. If you don’t want to vacuum your house after drywalling – low-dust drywall mud is the choice for you.
  • Drywall tape – although typically made of paper, it holds two sheets of drywall together firmly. Drywall tape has to be soaked first in drywall mud. After that you can put it on a joint between drywall sheets, and let it dry. Another, more expensive version of drywall tape is a fiberglass tape. This tape is more durable and easier to apply as it is self-adhesive.
  • Drywall corner bead – it serves to join drywall sheets at outside corners of walls. These areas are easily damaged during moving of furniture or even routine daily activities. Drywall corner beads are made of plastic or metal and can support many strikes.
  • Drywall screws – used to fix drywall sheets to walls or other firm objects. Nowadays, drywall screws have surpassed drywall nails as they don’t pop out.
  • Drywall T-Square – the essential drywall tool. Only by using drywall T-square you can be sure that your drywall panels are correctly in place.
  • Drywall saw – used to cut sheets of drywall so they can fit into more irregular spaces. It is more comfortable to use electric drywall saw, but manual drywall saw can do the job as well.
  • Cordless drill or drywall screw gun – to effectively load up or screw drywall screws
  • Drywall knife – used for slopping mud, tapping, and feathering. A smaller drywall knife will be better at slopping and tapping, while a bigger drywall knife will be more efficient at feathering and making some final corrections.
  • Sanding pole or sponge – for final sanding and smoothing. With sanding pole, you will reach higher places more easily.

After finishing the interiors, maybe it's time to go outside? We have prepared some fantastic calculators that will help you set up a wonderful yard for you and your family. Visit soil and mulch calculators to create optimal conditions for plant growth, and gravel calculator to lay some paths.

How much drywall do I need? – required drywall measurements

If you want our drywall estimator to calculate the number of panels you need, you will have to provide it with some data regarding your room. Make sure to input the following drywall measurements:

  • Room dimensions: you need to type in the length, width, and height of your room.
  • Ceiling: choose whether you want to include the ceiling in your calculations.
  • Room surface area: this value will be calculated automatically. Still, if your room has a different shape than a rectangular cuboid, you can also input the surface area directly into our drywall calculator. To calculate areas of uncommon shapes of walls visit our math calculators. Maybe one of your walls is trapezoid? Oh, and don't forget to check our circumference and circle calculators for some extravagant projects!
  • Doors: you can choose the default dimensions or type in custom ones. Once you type in the number of doors in the room, the drywall estimator will find their total area automatically.
  • Windows: again, you can leave the default dimensions of windows or customize them. If the windows vary in size, you can also calculate the total area manually.
  • Drywall panel type: choose the size of drywall panels you are going to buy. Our drywall calculator lists most common sizes in the USA and other countries. You can read more about different sizes of drywall in drywall sizes and drywall thickness paragraph.

Once you have decided on all of the values listed above, the sheetrock estimator will automatically display the number of drywall panels that you need. Remember to buy a bit more (ideally, 10% more) to account for all cut-outs, waste, and replacement (to see why, go back to the what is drywall (sheetrock)?) paragraph).

Calculating the area under sloped walls with drywall estimator

With our drywall calculator, you can also incorporate the area of spaces under sloped walls to the total room surface area calculation. How to do it?

  • Firstly, determine whether your room has sloped walls. Sloped walls exist in rooms directly under roof when there is no attic. Although sloped walls have a rectangular shape by themselves, they also limit other walls of the room typically creating a triangle-like shape at the top of them. It may look like this:

    ”image

  • Secondly, measure the height and the base of triangular space as shown in the picture. Height is marked with h and base is marked with b.

  • Now, we can perform our calculations. To get the area of this space we need to use the equation for the area of a triangle:

    area = height * base / 2

  • Finally, if there are some more identical triangular spaces in the room, multiply the estimated area of one triangular space by the number of all triangular spaces.

  • Watch out! If your room has sloped walls, you should measure the height of your room only to the base of triangular space under the sloped wall (not to the top of ceiling).

Remember, that there is no need to do all the calculations by hand. Our sheetrock calculator can do it all for you.

If you want rather use the plan of your house to do the drywall measurements, some coordinate system calculators may come in handy. With distance calculator, you will calculate the distance between two points. Midpoint calculator will always tell you where exactly is the middle point of any line. Finally, slope calculator will help you deal with angles and sloped walls.

Drywall cost calculator

You can also use the drywall cost calculator to find out what will be the total cost of all panels. Simply input the unit price in the Cost per panel field (in the USA it is typically $6 to $15 per panel, depending on its dimensions, see the how much is a sheet of drywall? - sheetrock prices in US paragraph). The drywall cost calculator will display the total drywall cost for you.

If you would like to see what is the net price of purchased drywall or how much sales tax you have to pay, visit our sales tax calculator. It will do all the calculations for you!

Kacper Pawlik and Bogna Haponiuk.

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