A paint bid is coverage math plus time math: gallons from wall area, hours from prep and coats. Get either side wrong and the job pays you less than the last one. These calculators do the coverage side instantly so the bid conversation starts from a real number.
A gallon covers roughly 350–400 sq ft per coat. A 12×14 room with 8-ft ceilings has about 400 sq ft of wall after door and window deductions — one gallon per coat, two coats for color changes. The paint calculator does the deduction math and coat count so the order is right the first time.
A 50% markup on $1,000 of cost gives a $1,500 price — which is only a 33% margin. Quoting "50% margin" when you mean markup is how bids come in thin. The markup-margin calculator converts both directions so the number you say is the number you get.
Start from the rate floor: target income plus insurance, vehicle, ladders, sprayer maintenance, and marketing, divided by realistic billable hours — typically 55–65% of the week, because estimates, color consultations, and prep runs don't bill. The freelance rate calculator builds that floor from your actual numbers.