Important reminder: Every effort has been made to ensure the accuracy of this calculation. But before purchasing materials for any project, please check amounts with your suppliers or contractors.
These calculations are for applying paint with a brush or a roller. If you use a sprayer, you'll need about 30 percent more paint.
When you're buying paint, don't skimp. Often, premium paint covers in one coat while bargain paint takes two. High-quality paint usually retains its luster, washability, and vibrancy longer than cheap paint. Also, by buying an adequate quantity at the start, you'll ensure that the tint is even throughout -- otherwise, if you have to buy extra, the tint may be ever so slightly off, even with computerized paint mixing.
A few tips: If the existing surface is stained, or if it has patched areas, apply a coat of stain-sealing primer before applying the paint. Also, use primer if you will be applying latex paint and the existing paint is oil-based (or if you suspect that it might be oil-based). A good paint store will tint primer -- at no extra cost -- to approximate the color of the finish paint.
If the new color is very different from the existing color -- and especially if the new color is lighter -- expect to apply two coats.
In an average room, painting the trim requires about 1/4 as much paint as the walls.