Flooring Calculator
Add every room that is getting the floor, take the closets, hearths and stair openings off, type the coverage printed on the box, and read back three numbers instead of one: the net area, the area once your waste allowance is on it, and the boxes to buy. The waste field opens at zero here, because the allowance is a decision rather than a constant. Whatever you type is added once, to the measured area, and the area it adds is printed as its own figure, so nothing is folded in twice. Two rooms coming to 216 sq ft take 11 boxes of 20 sq ft with no allowance and 12 at 10 percent, and the page shows both halves of that sum, so the extra box is never a mystery. Give the plank size as well and it counts planks and shows the row cut: how many rows fit across the room, how wide the last row is ripped, and how long the last plank in a row is cut.
Type a room width and length, in feet.
- Net area
- 0 sq ft
- With waste
- 0 sq ft
- Boxes
- 0
- Waste
- 0%
Rooms
One line per room. Measure wall to wall and take the closets and the hearth off below. In feet you can type the tape as you read it, so 12'6" is 12 feet 6 inches. Press Enter in any field to add another line.
- not yet
Exclusions to take off
A closet, a hearth, a kitchen island, a stair opening. Each one comes off the rooms before any box is counted.
The box and the waste
The coverage is the area printed on the box, and the waste allowance is yours: it opens at zero, and whatever you type is what gets added, once, to the measured area. Fitters commonly allow 5 to 10 percent on a straight room and more on a diagonal or a herringbone.
The plank, and the row cut
Optional. Give the plank face size and the page counts planks as well as boxes, and shows how wide the last row is ripped and how long the last plank in a row is cut. Leave both fields empty to skip it.
Worked examples
Each one runs through the same function as your own numbers. Load one to see it in the fields.
Common questions
- How many boxes of flooring do I need for 100 square feet?
- With a 10 percent waste allowance and a box that covers 20 square feet, 100 square feet needs 6 boxes. The working is 100 plus 10 percent, which is 110 square feet, divided by 20, which is 5.5, rounded up because a box is sold whole. With no allowance the same floor is exactly 5 boxes. The page prints those steps rather than a single total, so you can see which box is the one your allowance bought.
- How much waste should I allow for flooring?
- Fitters commonly start at 5 to 10 percent for straight rows in a plain rectangular room, and allow more for a diagonal or a herringbone, for a room full of alcoves, or for a long narrow board that wastes more at every end. This page has no figure of its own: the field opens at zero and whatever you type is what it adds, once, to the measured area. Two rooms coming to 216 sq ft become 237.6 sq ft at 10 percent, which is 12 boxes of 20 sq ft rather than 11.
- Can I add up several rooms and take a closet off?
- Yes, and that is the case this page is built for. Rooms are a list: a living room, a hall, a landing, each with its own name, width and length, and each showing its own area as you type. Exclusions are a second list for the parts that stay bare, such as a closet, a hearth, a kitchen island or a stair opening, and every one of them comes off the total before a single box is counted. The page holds up to 40 rows in each list, and it says so rather than quietly dropping a room.
- Can I type 12 feet 6 inches instead of a decimal?
- Yes. When the rooms are measured in feet you can type the tape as you read it, so 12'6", 12' 6 and 12 ft 6 in are all read as 12.5 feet, and 6" on its own is half a foot. Inches of 12 or more are refused with a note saying that 12 inches is another foot, rather than being read as something you did not mean. In metres, centimetres, millimetres or inches the fields take a plain decimal, and a box quoted in square metres works with a room measured in feet.
- What does the row cut tell me?
- Give the plank's face size and the page divides the room by it: how many rows of full-width planks fit across the room, how wide the final row has to be ripped, how many planks lie end to end along a row and how long the last one is cut. It assumes straight rows running along the room's length, starting from a full plank at one wall, and it is arithmetic rather than a plan for where every plank lands. It is worth seeing before you buy, because a final row two centimetres wide changes how a room reads.
- Does it say what goes under the floor, or whether this floor suits my room?
- No. The page counts what to buy and stops there: it says nothing about subfloor, underlay, moisture or acclimatising the boxes, and nothing about whether a floor suits a room. Those questions depend on the building and on the manufacturer's own instructions for the product you picked, which are the ones that count. What the page does is exact: it multiplies and divides the numbers you type and rounds the box count up.
- Is anything sent anywhere?
- No. Every measurement is read and multiplied in your browser and nothing leaves the page. Your rooms, exclusions, waste allowance, box coverage and plank size are remembered in your own browser storage so the page reopens where you left it, and clearing your browser data clears them. If storage is blocked the page still works, it simply opens on its defaults each time.
Exact arithmetic on the areas you enter, with the waste percentage yours and set to zero until you change it. Boxes are rounded up because they are sold whole; it gives no advice on subfloor, underlay or whether a floor suits a room.