How to Estimate Painting Costs
Written by Lee Wyatt (last updated September 21, 2022)
It can be extremely easy to either over estimate, or underestimate how much money it will cost to purchase paint for a renovation project. How to estimate painting costs is more than simply saying that you will spend X amount of money on paint and supplies. How to estimate painting costs is actually a rather simple process. All you really need to do is remember a few simple math tricks, and you will very easily be able to figure out how much paint you will need to purchase. Once you know how much paint you need to purchase, it is really easy to figure out the amount of money that you should set aside for your painting project.
- Ceiling. It is always a good idea to start with the largest area first, and when painting a room this will usually be the ceiling. Another trick to remember when figuring out how much paint to buy is to round all your figures up to the largest whole number. Measure the length of the room, and then the width. Multiply these two numbers together so that you will get the entire area you need to cover. For example, you have an 11-foot wide room by 14 foot long. Multiply these two figures together, and you will get a total of 154 square feet. Divide this number by 350 (which is the estimated number of feet that a single gallon of paint can cover) to figure out how many gallons you need to purchase for this part of the job. This would be 154 divided by 350, which gives you a total of 0.44. For the ceiling of this room, you only need to get one gallon of paint, which given its size, should allow you to do two coats out of the same can.
- Walls. Figuring out the walls is much the same as figuring out the ceiling. Measure the height and length of the largest and smallest walls, and then double the results. For example, your room is going to have two walls that are 11 feet long by 8 feet tall, while you have another two walls that will be 14 feet long by 8 feet tall. The math would look something like this: 11 x 8 = 88, 14 x 8 = 112, 112 + 88 = 200, 200 x 2 = 400. This means that you will need to get enough paint to cover 400 square feet. Divide this total by 350, and you get 1.14, which means that you should get about 1-1/4 gallons to provide a single coat to each wall. You will have a bit of paint left over from not painting things like windows, doors, and trim/
- Trim. If you have any molding in the room, you will want to paint that as well, though it will usually be a different color. Determine the length of all the molding, and then add it together. For example, In the room that we have been working with, you could have a simple chair rail around the room that will give you dimensions like this 11 + 14 + 11 + 14 = 50 feet. Multiply this amount by .5 so that you can get an estimated width of the molding, which will look like this: 50 x 0.5 = 25 square feet that you will need to paint. Once again, divide this amount by 350 to get the amount of paint you will need for the trim. In this case that will be .07, so you should only need one quart to paint all the trim in this particular room.
- Doors and windows. To figure out the amount of paint needed to paint your doors, multiply the number of doors by 20. In the room we have been working with you have one door to get in, one door to the bathroom, and one door to the closet. The math would look like this: 3 x 20 = 60 square feet. Now, multiply the number of windows by 7.5, and in this room you have four windows, so the math will look like 4 x 7.5 = 18 square feet. Add these two totals together (18 + 60 = 78 square feet) and then divide by 350 (78 divided by 350 equals .22). In this instance you will need to get 1/2 quart to paint the doors and window trim with only one coat.
- Add everything together. Once you have figured out the separate amounts for each part of the room, it is time to add everything together. For the this particular room, you will need to get a minimum of 2.75 gallons, or if you simply round up the total, three gallons to paint your room. This should give you enough paint to provide two coats for everything, with just a little bit left over. Take this figure and multiply it by however much the paint you are looking at purchasing is to figure out how much money you should set aside for purchasing the paint.
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