Flooring Calculator – How Much Flooring to Buy and How It Will Lay Out
This flooring calculator tells you how much laminate, luxury vinyl plank, engineered or solid hardwood, carpet or sheet vinyl to buy, in the units the store sells it: boxes for planks and linear feet or metres off the roll for carpet and sheet vinyl. It also plans the last row of planks, shows where carpet seams fall, adds up underlayment, pad and baseboard, and draws each room with the planks or strips laid in it at scale.
Measuring Rooms and Closets
Measure wall to wall at the widest point, at floor level. Enter each room as a rectangle, an L-shape (the overall size minus the missing corner) or a known area. Closets you are flooring are extra rooms, and identical bedrooms can share one line with a quantity. Fixed kitchen islands and built-in cabinets are entered as Subtract rooms, because a floating floor must never be pinned under them.
Choosing a Waste Percentage
Every row ends in a cut plank, and some boards have defects. Typical allowances are 10% for a straight lay, 15% for diagonal and 20% for herringbone. Solid hardwood gets about 5% more because lower grades include boards you will cull. The calculator adds the waste to the net area and rounds up to whole boxes once, on the total, so you never pay for a rounding error in every room: boxes = ⌈net area × (1 + waste) ÷ coverage per box⌉.
Expansion Gaps
Laminate and wood move with humidity, so floating floors need a gap of roughly 1/4–1/2 in (6–12 mm) at every wall and around pipes. Solid hardwood is often gapped at about its own thickness. The baseboard or quarter-round hides the gap. The gap does not reduce the amount you buy, but it does change how many rows fit.
Planning the Last Row
Divide the room width, minus both gaps, by the plank's visible face width. The leftover is your last row. If it is narrower than about a third of a plank, it is hard to cut, fragile and looks like a mistake. The fix is to rip the first row too so both edge rows are equal: (leftover + plank width) ÷ 2. The row plan shows this for both directions, because turning the planks 90° often removes the sliver entirely.
Plank Direction
Planks usually run parallel to the longest wall or toward the main window, which makes a room look longer and hides the joints. Direction doesn't change the amount you buy in a simple room, but it decides where the rip falls.
How Carpet and Sheet Vinyl Are Sold
Carpet and sheet vinyl come off a roll, usually 12 ft wide (or 4 m for carpet and 2 m for sheet vinyl outside North America). You buy whole strips, each cut a few inches long at both ends for trimming to the wall. A room 13 ft across needs two 12 ft strips, and the extra 11 ft of width is waste. The calculator tries both roll directions and picks the one with the shortest length to order, then shows each seam.
Underlayment, Pad and Trim
Laminate and floating engineered floors need a foam underlayment unless it is pre-attached; most luxury vinyl plank already has a pad. Carpet needs carpet pad, which is priced by area. Both get about 5% extra for edge offcuts. Baseboard or quarter-round is the room perimeter minus doorways, plus 10% for mitres, rounded up to whole pieces. Adhesive, nails, moisture barrier and levelling compound aren't included; check your product's instructions for those.
Acclimate Wood Before You Install
Hardwood and many laminates must sit in the room, in their boxes, for a few days so they reach the room's temperature and humidity. Installing straight from a cold garage can lead to gaps or buckling later. Buy all your boxes at once and check that the lot numbers match, so the colour is consistent.