Paint coverage calculator
Measure the room once. This counts the walls, takes the doors and windows off, and tells you what to put in the van.
Nothing is sent anywhere: the arithmetic runs in this page. The prefilled rates are the ones a new Drawlite account in this trade starts with, and the first thing you would do in the app is replace them with yours.
Why a gallon does not cover what the can says
A can that claims 350 square feet means 350 square feet of one coat on a surface that does not drink. The trade quotes two coats, so the number that belongs in a price book is half of it. The seeded wall finish carries 175 square feet per gallon for exactly that reason, and the primer -- one coat, and only over bare and patched areas -- carries 300.
Getting this wrong is not an estimating error you find out about in the office. You find out about it at four on a Friday afternoon, one wall short.
What comes off the wall
Doors are deducted at 21 square feet and windows at 15, which are ordinary working figures rather than a measurement of yours. If your openings are nothing like that, change the count or measure them; the point of a deduction is to be stated, not to be precise.
Material is not the quote
The last line shows the same wall priced at the seeded rates, which include preparation, cutting in, masking and the second coat. The gap between the two numbers is the job.