Before you begin any painting project, you need to estimate the required amount of paint. To make a proper projection, you need to specifically figure the amount of paint that will be required for a specific surface area.

**Estimating the Square Footage**

In order to perform the calculation, you first need to add the lengths of all the room’s walls and multiply the total by the height of the walls. This height runs from the floor to ceiling. When you make this calculation, you will receive a room’s square footage.

**Determining the Wall Area That Will Need Paint**

Next, you need to figure how much of the room’s square footage will be painted. Because a different kind of paint is normally used for windows and doors, subtract these spots from the overall total. To make it easy, subtract fifteen square feet for a medium-sized window and twenty square feet for each room door. When you make this type of projection, you will come very close to the amount of wall area you will be painting.

**Consider the Number of Coats**

To make it even easier, plan on using one gallon of paint for every 350 square feet. You will need to use a bit more than this amount if the walls are made of drywall. That is because paint penetrates more readily in walls made from this substance. You also have to make allowances for walls that are darker in color, as these surfaces generally take two coats of paint.

**Firming Up an Amount**

To find the number of gallons of paint you need to buy for your painting project, simply divide the overall wall area that is to be painted by 350, or the square footage for one gallon. If the resulting number is more than 0.5 over the round number, buy an additional gallon of paint. However, if the remainder is less than that amount, buy two quarts of paint in addition to the gallons needed.

**Figuring Your Paints Needs for Molding and Trim**

If you are painting woodworking such as trim, you need to measure the trim in terms of feet and then multiply that number by 0.5 or six inches (half a foot). This will give you a rough estimate of the trim’s width. Calculate your paint needs for the trim around the doors, baseboards, and windows, as well as the trim running along the ceiling. For example, suppose you want to paint molding. First you need to calculate the entire length of the molding. You do this by adding up the lengths of the walls that feature molding.

**Round Your Answer**

Then, round the total number to the closest foot. Multiply this answer by 0.5. Again, this is done to calculate the width. Take the answer and divide it by 350 to determine the amount of paint needed for the trim. Usually, in most cases, the answer is less than a quart. However, you may want to paint other woodwork with the same color too. Therefore, buying a full quart in this case may be advantageous.

Once you have at least an idea of your paint needs, record what you actually end up using. That way, you will better know how much to buy if you paint the same room again after several years, or you want to paint a similarly-sized room in your business or residence.