WxH. 1900 means nothing but the floor space. It has nothing to do with the walls.

NO....NO.. 100 gallons would paint the whole street neighborhood!!! One home and 100 gallons is a scam big time. Prime and paint would not be close to that! I am a painter and my whole family is paint contractors and WOW....NO

Ken

You need to know the square footage of the interior walls and ceilings and the exterior walls plus estimate the areas of trim. Then, how many coats? If there's a major change in color, figure 2 coats. Exterior, 2 coats. Primer? That's another coat.

Knowing that, you can figure it out (about 400 sq. ft./gallon for each coat of interior, less for exterior). So for 8-foot high walls, that's about 50 running feet of wall per coat (a 12x12 room, one coat).

100 gallons?! WTH? is he on crack?

sq footage is heightXlength. if your wall is 8' and it's 10' long, that's 80 sq ft. Do that for each wall that's getting paint.

(usually one gallon will be enough to do the walls in a 10X12 room. give or take). Better paint quality gives you better coverage which means less paint. If you read the paint can it will give you the approx sq ft coverage on the can.