Painting Guides
The calculators give you a number. These guides explain where the inputs come from, which assumptions matter, and how to tell a paint estimate that will hold from one that will run short.
Measuring & coverage
Dark colours, LRV and the extra coats they cost
A navy wall can take half as much paint again as a pale one. The number on the back of the paint chip tells you before you buy, and a tinted primer is usually the way round it.
How many coats of paint you really need
The number of coats changes the order more than any other input. Here are the rules, the reasons behind them, and the cheaper way round a third coat.
How much paint do I need? The complete method
Five steps turn a tape measure and a paint can label into an order that will not run short, and a worked room shows each of them with real numbers.
Measuring a room for paint (and what to subtract)
Ten minutes with a tape measure is all a paint estimate needs, if you measure the right things and subtract only what is worth subtracting.
Paint can sizes, 5-gallon savings and the leftover problem
The cheapest way to buy 3.6 gallons is four gallons, not three and three quarts. A little arithmetic on can prices saves money, and a plan for the leftover saves the next repair.
Paint coverage explained: why 400 sq ft a gallon rarely happens
The coverage on the can is a laboratory number. Here is what eats into it on a real wall, by how much, and which figure to plan with instead.
Primer: when you need it and when you can skip it
Primer is either essential or a waste of a day, depending on the surface. Here is how to tell which, which primer to buy, and how much.
Interior projects
Painting a room: quantities, order of work and timing
Ceiling, walls, trim, in that order, and about two days of work for a bedroom. Here is the shopping list, the sequence and the hours, worked through for one real-sized room.
Painting kitchen cabinets: how much primer and paint, and why
A kitchen of cabinets is only about 180 sq ft of surface, but it is the hardest-wearing paint job in the house. The quantity is small; the prep and the product decide whether it lasts.
Textured and popcorn ceilings: coverage, product and technique
A popcorn ceiling can take two thirds more paint than a smooth one of the same size. Here is why, how to plan for it, and how to paint it without pulling the texture down.
Trim, doors and windows: the quart maths
Trim is a small area and a lot of work. Here is how to turn linear feet and door counts into quarts, and why the answer is usually two or three quarts more than people think.
Two-tone and wainscot walls: proportions, paint and a sharp line
A colour split at a third of the wall height, darker below, is the classic. Here is how to choose the height, how much of each colour to buy, and how to get a line that is straight and sharp.
Exterior projects
Deck stain coverage: new wood, weathered wood and product type
Deck stain coverage is set by the wood, not the can. A new, smooth deck might take a gallon; the same deck weathered and grey takes two. Here is how to tell which you have.
Measuring a house exterior for paint
You do not need a ladder to measure a house. A tape round the outside, a count of the storeys and a careful look at the gables give a paint estimate within a can or two.
Planning a fence stain: sides, styles and weather
A 100 ft privacy fence, both sides, is over 1,200 sq ft of rough wood, three and a half times the walls of a 12 × 12 ft bedroom. Here is how to plan the stain, the days and the weather.
Siding types and how much more paint rough surfaces take
The same house takes 9 gallons in smooth panels and over 13 in painted brick. Here is where the extra goes, which product each surface needs, and how to plan for it.
Cost & hiring
DIY or hire a painter: an honest break-even
The real question is not "how much will I save" but "how much will I save per hour of my weekend". Divide the saving by your hours, and the decision usually makes itself.
How to read a painting quote (and compare two)
Two quotes for the same rooms can differ by double, and the cheaper one is not always the better deal. Here is what to look for line by line, and how to put them on the same basis.
What painters charge: per square foot, per room, per hour
Interior painters charge roughly $1.50 to $4 per square foot of wall, according to published cost surveys. Here is what that means for a room or a house, and why quotes for the same job can differ by double.
Tools & techniques
Airless spray tips explained: the three digits
A 517 tip sprays a 10 inch fan through a 0.017 inch hole. Once you can read the number, choosing a tip for any paint and any pump takes a minute.
Dry, recoat and cure: how long paint really takes
Latex is dry to the touch in an hour and not fully hard for about three weeks. Knowing which clock you are on decides when to recoat, when to rehang doors, and when to wash the walls.
Painting production rates: how long a room, a wall, a door takes
A painter with a roller covers about 200 sq ft of wall an hour, one coat, cutting in included. A door takes about 45 minutes a side. Those two numbers explain most painting schedules.
Spraying vs rolling: paint usage, overspray and finish
A sprayer is several times faster at putting paint on a wall and always uses more paint doing it. Whether it saves time on your job depends on the masking, not the spraying.
Wet film, dry film and volume solids: coverage for pros
Every coverage figure on a can comes from one line of arithmetic. Learn it and you can compare paints honestly, check a crew's film build, and predict coverage for any coating.
Wallpaper
Wallpaper paste, prep and removal planning
The paper is the visible part of a wallpaper job. The primer under it, the right paste, and the hours of removal before it decide whether it goes up smoothly and comes down again in one piece.
Wallpaper roll maths: double rolls, repeats and drop match
Wallpaper is not bought by area. A room is a number of drops, each cut to the pattern, and the rolls are however many it takes to give you that many drops. Here is the arithmetic.
Pro & business
Building a painting bid: labour, materials, markup and margin
A bid is five numbers added in the right order. Get the order wrong, or confuse margin with markup, and a job that looked profitable pays less than planned.