Enter a room's length, width, and door/window openings once and get flooring boxes (with waste), tile count for wet areas, and baseboard/casing footage together.
“How much flooring do I need” starts with square footage, but the real order quantity depends on material, layout pattern, and waste percent — and most flooring jobs also touch tile in a wet area and new baseboard around the room. This page runs Room Layout once for floor area and perimeter, then feeds that into Flooring, Tile, and Trim. Each calculator below is the same one available on its own page — nothing here is a new formula.
Flooring material estimating: sq ft and waste %
Flooring waste percent depends on both material and layout pattern: a straight-run install wastes the least, while diagonal and herringbone patterns cut more material at the perimeter and need a higher waste allowance. This calculator locks in a waste percent per material/pattern combination (hardwood, engineered, LVP, or laminate, each with straight/diagonal/herringbone options) and applies it to the room’s floor area before rounding up to whole boxes.
Floor area comes from Room Layout’s length x width, so changing the room dimensions updates the flooring box count automatically without re-entering area by hand.
Room dimensions, doors, and windows
Enter room length, width, and doors/windows once. Flooring, tile, and trim each add a few fields of their own below (material, tile size, waste percent) that a room's dimensions alone don't determine.
Room Layout
Floor area and perimeter from room length and width — the shared backbone for Flooring, Tile, and Trim below.
This room has — sq ft of wall and — sq ft of floor.
This room has
Room Layout result
Detail values
Perimeter
— ft
Wall area
— sq ft
Wall segments
ft
Assumptions
Formula details
Floor area: 0.5 x abs(sum(xi x yi+1 - xi+1 x yi))
The shoelace (surveyor's) formula for the area of a simple polygon, wrapping the last vertex to the first; the perimeter is the Euclidean distance summed around that same closed list. Both are mathematical identities -- no trade convention and no published source stands behind either, and none is needed.
Tile count, grout weight, and thinset bags for the tiled part of this floor — the area you enter above, which comes off the flooring total.
You'll need — tiles and — lb of grout for 0 sq ft.
You'll need
Tile result
Warnings
ERROR Enter the area being tiled -- without it there is nothing to count.
Detail values
Tiled area
0 sq ft
Tiles needed
—
Grout fraction of module
0%
Thinset weight
— lb
Assumptions
Grout type: Unsanded (estimated 100 lb of grout powder per cu ft of joint -- a trade working figure, not a manufacturer data sheet)
Grout joint: 0.125 in wide, 0.375 in deep (the joint runs the full thickness of the tile -- enter that thickness as the depth)
Trowel notch: 1/4" x 1/4" square notch (~0.1875 in of bed once the ridges collapse -- an estimated rule of thumb, shown as a sanity check; the bag count comes off the coverage row below, not from this)
Thinset bag weight: 50 lb
Thinset coverage: 95 sq ft per bag at 1/4" x 1/4" square notch (check the bag)
Back-butter: No
Estimated waste: 10% for an average project
Formula details
Grout coverage ratio: (tile L × tile W) / ((tile L + gap) × (tile W + gap))
Tessellation geometry, not an allowance: each tile sits in a module one joint wider and one joint longer, and whatever the tile does not cover is grout. Nothing is estimated in this ratio.
Coverage per bag as printed on the bag, halved when back-buttering -- that halving is an estimated trade allowance, not a manufacturer figure. NOT area × notch depth × dry density -- that treats a ridged bed as a solid slab AND counts the mix water as powder, over-ordering ~2.5x.
Baseboard, door casing, and window casing footage from the room's perimeter and openings.
You'll need — ft of trim for this room.
You'll need
Trim result
Warnings
ERROR Enter the room perimeter -- without it there is no baseboard to count.
Detail values
Baseboard linear feet
— ft
Door casing linear feet
— ft
Window casing linear feet
— ft
Assumptions
Trim context: Interior (MDF, finger-joint, or wood baseboard & casing)
Door casing faces: Not stated -- door casing is not counted until this is answered (see gaps)
Window casing: Picture-frame casing, all four sides (2 x height + 2 x width per window). Stool-and-apron is NOT modelled: it has no bottom casing leg but adds a stool and an apron this figure does not count.
Estimated waste: 10% for an average project
Estimated finish nails: 1.5 per foot of trim counted -- a jobsite practice figure, not a published fastening schedule
Tile is sized from the tiled area you enter, not from the room’s whole floor — a bathroom, laundry, or mudroom footprint, or a shower alcove inside a larger room. That area comes off the flooring total, so the two materials split one floor between them instead of each covering all of it. Tile count factors your tile size and waste percent; grout weight and thinset bag count come from joint width, joint depth, and a density constant you can adjust for your grout product.
If the whole room is tiled, enter the full floor area here and the flooring box count drops to nothing. Leave it blank and the tile section stays empty rather than reporting zeros for a floor nobody said was tiled.
Trim and baseboard footage
Baseboard runs the room’s perimeter minus door widths (a door interrupts the baseboard run at floor level), while door and window casing is a separate linear-footage total based on each opening’s width and height. This page tracks doors and windows as two separate lists so Trim can subtract door widths from the baseboard run while still casing both doors and windows.
Perimeter comes from Room Layout, so a longer or shorter room updates the baseboard total the same way it updates flooring and tile above.
FAQ
Why does Tile ask for its own area instead of using the whole room?
Because a floor gets one covering, not two. Running the room's full floor area into both Flooring and Tile ordered a complete floor of boxes and a complete floor of tile for the same square footage, and both reached the material list. Nothing in a room's length and width says how much of it is tiled, so this page asks: enter the tiled part (a shower alcove, a laundry, a bathroom footprint) and it comes off the flooring area. Leave it blank if nothing is tiled, and enter the whole floor area if the whole floor is.
Why are doors and windows tracked separately instead of one combined opening list?
Trim needs door widths subtracted from the baseboard run (a door interrupts the floor-level baseboard) while both doors and windows get their own casing footage. Room Layout combines both lists into one openings set for its own wall-area math.
How is flooring waste percent determined?
Waste percent is a locked reference table by material and layout pattern (hardwood, engineered, LVP, or laminate, each with straight, diagonal, or herringbone options) -- it isn't user-editable on this page since it reflects typical cut loss for that combination.
Can I fine-tune just one calculator without changing the room dimensions?
Yes. Flip any section to "Manual entry" to edit its inputs directly without changing the room layout or the other calculators.
Disclaimer
Material estimate and general reference only. Verify manufacturer waste recommendations, grout/thinset coverage, and field conditions before ordering or starting work.