Laminate Flooring Calculator

Calculate how many boxes of laminate flooring you need for a room, plus the rolls of underlayment and the quarter round or trim to finish the edges.

By CalcBuilt Editorial TeamUpdated September 9, 2026Formulas checked against manufacturer specs, see how we calculate.

Quick answer: To find how much laminate you need, multiply room length by width, add 10% for waste, and divide by the coverage per box; underlayment is the floor area divided by 100 sq ft per roll, and trim is the perimeter minus 3 ft per doorway. A 12 x 10 ft room needs 132 sq ft of laminate including 10% waste, which is 7 boxes at 20 sq ft per box, plus 2 rolls of underlayment and 41 ft of quarter round.

Results

Laminate to buy: 132 sq ft; 120 sq ft floor area plus 10% waste
Boxes needed: 7 boxes; 140 sq ft purchased
Underlayment: 2 rolls; 100 sq ft per roll, covering 120 sq ft
Quarter round or trim: 41 ft; 44 ft perimeter minus 3 ft for 1 doorway. Buy 6 pieces of 8 ft.

Laminate Flooring formula

Floor area (sq ft) = Length (ft) x Width (ft) + closets and hallways
Boxes = Floor area x (1 + waste %) / coverage per box, rounded up
Underlayment rolls = Floor area / 100 sq ft per roll, rounded up
Trim (ft) = 2 x (Length + Width) - 3 ft x doorways

Worked example

A 14 x 16 ft living room with two doorways: 14 x 16 = 224 sq ft. Add 10% waste for 246.4 sq ft. With boxes that cover 22.5 sq ft, 246.4 / 22.5 = 10.95, so buy 11 boxes (247.5 sq ft).

Underlayment: 224 / 100 = 2.24, so buy 3 rolls. Trim: the perimeter is 2 x (14 + 16) = 60 ft, minus 6 ft for the two doorways = 54 ft of quarter round, which is 7 pieces of 8 ft.

Quick reference

Laminate needed for common rooms (10% waste, 20 sq ft boxes, one doorway)
Room size	With 10% waste	Boxes	Underlayment rolls	Trim
10 x 10 ft	110 sq ft	6	1	37 ft
10 x 12 ft	132 sq ft	7	2	41 ft
12 x 12 ft	158 sq ft	8	2	45 ft
12 x 15 ft	198 sq ft	10	2	51 ft
15 x 20 ft	330 sq ft	17	3	67 ft
20 x 20 ft	440 sq ft	22	4	77 ft

How to calculate laminate flooring

Measure the room at its longest and widest points and multiply for square feet. Add closets and any hallway you will run the same floor into. Add 10 percent for waste on a straight layout, or 15 percent if you are laying diagonally or the room has many alcoves, and divide by the coverage printed on the box. Round up, and keep one spare box for repairs.

Underlayment goes over the floor area only, so do not add waste to it. If the planks come with an attached pad, skip it, but you may still need a 6 mil polyethylene vapor barrier over a concrete slab. Check the installation guide, since some manufacturers void the warranty if you double up pads.

Expansion gaps, trim and acclimation

Laminate is a floating floor and moves with humidity. Leave a 1/4 to 3/8 inch gap at every wall, cabinet, pipe and door jamb. Quarter round or base shoe nailed to the baseboard, never to the floor, hides the gap. The trim length is the room perimeter minus the doorways, where a transition strip is used instead.

Buy an AC3 rated product or better for living areas and AC4 for kitchens and entries. Let the sealed boxes sit flat in the room for 48 hours so the planks match the room temperature and humidity before you click them together.

Key facts

Laminate is rated AC1 to AC5 for wear; AC3 is the minimum for a busy home and AC4 suits kitchens, hallways and light commercial use.
Leave a 1/4 to 3/8 in expansion gap at every wall and fixed object; quarter round or base shoe covers the gap.
Let boxes acclimate flat in the room for at least 48 hours before installation.
A roll of foam underlayment typically covers 100 sq ft; laminate with an attached pad does not need a separate roll.
Common laminate thicknesses are 7 to 12 mm; a typical box covers 18 to 24 sq ft.

Frequently asked questions

How many boxes of laminate do I need for a 12x12 room?

A 12 by 12 room is 144 square feet. With 10% waste that is 158 square feet, which is 8 boxes at 20 square feet per box.

Do I need underlayment under laminate flooring?

Yes, unless the planks have an attached pad. Foam underlayment evens out small subfloor flaws and reduces noise. Over concrete you also need a vapor barrier, either built into the underlayment or a separate 6 mil sheet.

How big should the expansion gap be for laminate?

Leave 1/4 to 3/8 inch at all walls and fixed objects. Rooms longer than about 40 feet in either direction also need a transition strip in the field.

How long should laminate acclimate before installing?

At least 48 hours in the room where it will be installed, with the boxes flat and unopened, at normal living temperature and humidity.

Sources and references

Laminate flooring FAQs: subfloors, underlayment and vapor barriers (NALFA)
How to install laminate and vinyl flooring (Pergo)
ROBERTS Serenity foam underlayment, 100 sq ft roll (QEP (Roberts))

Next steps for this project

The usual order for a flooring & tile project. See all flooring & tile calculators.

Results are estimates based on standard formulas and typical product specifications. Confirm quantities with your supplier and local code before ordering.