Measure the area of the room where the carpet will be placed. Measure along the north wall to get the width, then along the eastern wall for the length. Write down these measurements, and then multiple the width by the length. For a 12 by 13 foot room, for example, the area is 156 square feet.
Contact or visit a local home improvement center to compare padding types. Distinct varieties, each meant for a specific purpose, exist. Felt is made of jute, an Asian plant fiber substance, and is suited perfectly for wooven carpets. Urethane is widely available in many thicknesses for most any carpet types, as is rebond, the recycled form of urethane.
Price the padding that best suits your carpet by using the dimensions you have drawn up. A common roll of padding will be 6 by 45 feet. This puts the square feet at 270. One roll of this padding will be sufficient enough to complete the room listed above at 156 square feet.