How to Measure the Area of a Room

Knowing how to measure a room's area accurately is useful for home renovations, such as laying flooring and painting walls. Depending on why you're measuring the room, you may need to apply different methods. For example, if you're planning to install flooring, you'll need to know the floor area; if you're painting the walls, you'll need to calculate the wall and ceiling areas, and so on. This task can be tricky if you've never done it before, and it may become more complicated due to built-in features of the room like slanted ceilings, alcoves, or windows that protrude outside.

Sketch a floor plan of the room you're measuring. You'll use this sketch to note all measurements. The drawing doesn't need to be to scale, but the more accurate, the better.

• Since you're only measuring the floor area, it's fine to include windows and doors in the sketch.
• Make sure to include all surfaces that need to be calculated. For example, if you're measuring the floor area, including a walk-in closet, make sure to draw it in the diagram.
• In the example sketch, the bathroom is on the right (it's a separate room, so it doesn't need to be drawn) and the window is on the left (represented by a semicircle).

Measure the length and width of the main area of the room. To calculate the room's area, use the standard formula: Area = (Length) x (Width). Measure the length and width at the furthest points of the room. This is crucial for obtaining accurate measurements.

• Move furniture or other objects out of the way while measuring.
• Have someone hold one end of the measuring tape.
• For now, only measure the main area. Skip windows and other specific sections like the bathroom at this stage.

Multiply the length and width to calculate the main surface area. Use a calculator for more accurate results. For example, if the room is 3.6 meters wide and 3.6 meters long, the floor area will be 12.96 square meters. This result represents the total floor area of the room. Record this value on your drawing.

Measure the length and width of square or rectangular wall recesses. These parts often include wardrobes or bathrooms that are part of your room's floor plan. Measure the recesses as you would for the main area. Measure the length and width of the recess and multiply them to find the area of the recess.

• Write the results in the designated recess section of your drawing.
• Repeat this step if there are multiple recesses in the room.

Calculate the area of circular wall recesses. Measure the longest dimension (usually across the center of the circle) and the width of the recess. Don't measure beyond the edge of the main area you've already measured. Then, divide the length by 2. Multiply this result by the width. Continue by multiplying everything by pi (3.14), and finally divide the area by two.

• Record the results in the recess section of your drawing.
• You now have the results for the U-shaped protrusion in the room.
• The area of a window that protrudes outward should only be included in the room area if the window is flush with the floor (not having a sill) and the ceiling is at least 2.13 meters high.

Add all the results together to get the total floor area. Combine the area of the recesses with the main floor area. Now, you have the total floor area of the room, which allows you to purchase carpets, tiles, or other materials based on this area.

Draw all the walls you need to measure. Include doors and windows in your drawing. Make sure to leave enough space to write down the measurements.

Measure the width and height of the wall. To calculate the area of the wall, use the standard formula: Area = (Height) x (Width). Use a tape measure to measure both the width and height of the wall. Since walls are usually tall, you might need someone to help hold the tape measure. Record the measurements on your drawing.

Multiply the height and width together. Use a calculator to multiply the height and width of the wall. This will give you the total area of the wall. Write the result down.

Measure the length and width of all doors, fixed details, or windows. Record the length and width of doors and windows on your drawing.

Measure the length and width of the door, fixed details, or window. Use a handheld calculator to multiply the length and width of the existing door or window. Record each result. This represents the area of the door, window, or fixed detail.

Sum up the areas of all doors, fixed details, or windows. This method applies when a wall has more than one door, fixed detail, or window. Record the final result.

Subtract the result from step 6 from the total area of the wall. Use a handheld calculator for this step. The result equals the area of the wall, which you can use to purchase paint or wallpaper.

Measure the length and width of a square or rectangular room. Use the standard formula: Perimeter = 2(Length + Width) to calculate the perimeter of the room. Use a tape measure to measure the room's length and width.

Add the length and width together, then multiply the result by 2. Use a calculator to ensure accuracy. After adding the length and width, multiply the result by 2 to find the perimeter of the room.

Calculate the perimeter of a room with a different shape. If the room you're measuring isn't square or rectangular, you'll need to measure each side of the room. Measure around the room and record the length of each side.

Add all the measurements together. Use a calculator to sum up the results of the room's measurements. The final result is the perimeter of the room.

Calculate the floor area. This method was described in Method 1. If the ceiling is flat, by calculating the floor area, you already have the ceiling area. For a square or rectangular room with a flat ceiling, the ceiling area equals the floor area. If the ceiling has protruding or recessed parts, continue with Step 2.

Measure the area of the additional parts of the ceiling. This step applies only when the ceiling is not flat. Many ceilings feature wall recesses and protruding windows; measure the length and width of these areas. Record the measurements.

• If the ceiling is sloped or has wall recesses or other shapes, it may have a larger surface area than the floor, so be sure to account for this when purchasing materials (which means buying extra materials).
• Ceilings are hard to reach. If you're measuring the ceiling area, ask a friend to help you.
• You will need a ladder to measure the ceiling area.

Add the measurements of the additional ceiling parts to the room's total area. Add all the measurements you collected in step 1 to the result from the previous calculation. Record the total.

Measure the area of any windows on the ceiling. If there are no windows, skip this step. Occasionally, ceilings are designed with windows, and you will need to subtract these areas from the total ceiling area calculated in step 3. Measure the length and width of the ceiling windows. Multiply the length by the width to obtain the area of the windows.

Subtract the window area from the ceiling area. Take the total ceiling area and subtract the result from step 4. This will give you the final ceiling area.

• If you are measuring to replace the flooring with wood, tiles, or laminate, calculate the floor area as mentioned, but be sure to buy extra materials to account for waste and any pieces that will be cut off. The industry standard for scrap material is 10%.
• Use a handheld calculator to compute the measurements.
• Ask a friend to help make the process smoother. One person can record the measurements while the other takes the measurements.

• Measuring tape
• Pencil
• Paper
• Handheld calculator
• Ladder