Floorings Calculator guides
The calculators give you a number. These guides explain where the inputs come from, which assumptions matter, and how to tell a good estimate from a bad one.
Carpet
Carpet padding: density, thickness and how much to buy
The pad decides how a carpet feels and how long it lasts. Density matters more than thickness, and the carpet's warranty usually tells you the minimum of both.
Carpet roll math: why a 13 ft room costs so much more than a 12 ft one
Carpet is bought by the length of a roll 12 ft wide. A room up to 12 ft wide in one direction takes one piece. A room an inch wider takes two, and pays for a whole second strip.
Carpeting stairs: full-width carpet or a runner, and how much
Stair carpet is counted by the step, not by the area. Each step takes the tread, the riser and the nosing, and a flight of fourteen is about 22 ft of carpet before landings.
Rug size rules for living rooms, dining rooms and bedrooms
A rug is sized by the furniture on it, not by the room. Too small is the common mistake. Here are the rules for each room and the standard sizes they lead to.
Wood & laminate
Expansion gaps: how wide, where, and why floors buckle
Every floor moves. The gap at the walls is the room it moves into, and a floor without one buckles, cracks or lifts. Here are the gaps for each type and the arithmetic behind them.
Hardwood vs engineered wood vs laminate: cost, life and quantities
Three floors that can look alike are built very differently. Solid wood lasts generations and costs most; engineered wood goes where solid cannot; laminate costs least and is replaced, not refinished.
Refinishing a hardwood floor: grits, sandpaper, time and finish
A worn wood floor can look new again for a fraction of the cost of replacing it. The job is mostly sanding, and the sanding is mostly arithmetic: area, grits, abrasive life and time.
Underlayment: which type, how many rolls, and when you need none
Underlayment smooths small flaws, softens footfall, cuts noise and keeps slab moisture out. The right one depends on the floor above and the subfloor below, and sometimes the right one is none.
Which way to run planks, and how to avoid a thin last row
Plank direction is a choice about light, joists and the longest view. The last row is arithmetic, and it is the one you should do before laying the first plank.
Cost & hiring
Removing an old floor: cost, time, debris and what to watch for
Taking up the old floor is the dirty, heavy part of every flooring job. Carpet comes up in an afternoon; tile set in mortar takes days and weighs a ton. Here is what to expect for each.
What flooring installers charge, and how to read a quote
Labour is often as much as the floor itself. Here are the usual ranges per square foot for each floor, what moves them, and the questions that make two quotes comparable.
Measuring & waste
Flooring waste factors: 5%, 10%, 15% or 20%?
The right waste allowance is the one that matches your layout and room, not the one everybody repeats. Here is where 10, 15 and 20% come from, and the adjustments that move them.
How much flooring do I need? The complete method
Measure the room in rectangles, add the waste your layout demands, divide by what the box really covers, round up once, and count the trim. Here is each step, with a living room worked from start to finish.
Measuring L-shaped, angled and odd rooms for flooring
Any room can be measured as rectangles that do not overlap. Here is how to split the awkward ones, what to include and leave out, and why an L-shape has the same perimeter as a plain rectangle.
Square feet, square yards and boxes: the units of flooring
Tile is priced per square foot, carpet per square yard, European products per square metre, and you buy all of them by the box or the roll. Here are the exact conversions and the traps between them.
Vinyl & resilient
Buying luxury vinyl plank: boxes, wear layer, pad and price
Vinyl plank is the easiest floor to buy wrong, because boxes, thicknesses and wear layers vary so much. Here is what to read on the label and how to turn a room into boxes.
Garage tiles, gym rubber and play mats: counting the floor
Garage, gym and playroom floors are sold as tiles, rolls or mats rather than boxes of flooring, and each format wastes differently. Here is how to count each one, and what each weighs.
Sheet vinyl: roll widths, seams, pattern match and how much to buy
Sheet vinyl comes in rolls 6, 12 or 13.2 ft wide, and you buy a length. A room that fits the roll needs no seam and wastes little; a room just over it can waste 40%.
Tile
Large-format tile: what it needs before you order
Big tiles look clean and save grout, but they need a flatter floor, deeper mortar, leveling clips and careful layout. Here is what changes in the order and on the floor when a tile side reaches 15 inches.
Thinset coverage by trowel size: how many bags of mortar?
The notch on the trowel decides how much mortar goes under each square foot, and so how many bags you need. A floor of large tile can take three times the mortar of the same floor in small tile.
Tile size, grout joint and what they do to your quantities
A tile and its joint decide almost every other number on a tile job. Bigger tiles mean fewer joints and less grout but a flatter floor and more mortar; wider joints mean fewer tiles but much more grout.
Tiling a shower: every quantity, from walls to the floor
A shower is three walls, a floor, a niche, a curb and a lot of edges. Each has its own quantity, and the edges are the one people forget. Here is the whole list for a standard alcove.
Subfloor & prep
Electric radiant floor heating: area, watts, circuit and running cost
Electric floor heat is sized by the open floor you stand on, not the room. Here is how to work out the heated area, the load on the circuit and the monthly bill for a bathroom and a kitchen.
How much self-leveling compound? Depth, bags and primer
A bag of leveler covers about 47 sq ft at 1/8 inch and half that at 1/4 inch. The depth is everything, and it is the number most people guess. Here is how to measure it and turn it into bags.
Subfloor preparation: flat, dry, sound and clean before any floor
Most flooring failures start underneath. A floor that is flat, dry, stiff and clean takes any finish; one that is not ruins the best plank or tile. Here are the checks and the fixes.