Things You'll Need
The shower pan is the floor area of a walk-in shower where water accumulates and drains away. When you shower, the shower pan is the surface on which you stand. When building a shower pan, you will need to know the dimensions to figure out the quantity of the materials that you need to purchase.
Use a tape measure to measure the width of the shower pan in inches across the opening from left to right. This measurement will be called the width measurement.
Measure the depth of the shower pan in inches from the back of the shower pan to the doorway, or opening, of the shower pan. This measurement will be called the depth measurement
Multiply the two measurements together to find the total area of the shower pan. This will give you a number in square inches. For example, if your shower pan is 42 inches wide by 44 inches deep, the shower pan will be 1,848 square inches.
Divide the number of square inches by 144 to find the number of total square feet.
1,848 / 144 = 12.8333 square feet, or 13 square feet.
Always round up when figuring the amount of building materials needed for a project.