🪵 Flooring Calculator

How to Calculate Flooring

Flooring is sold by the box, but measured by the square foot, so every estimate runs the same three steps: find the area, add a waste allowance, then divide by the coverage printed on the box.

The step people skip is rounding up to whole boxes. You cannot buy two-thirds of a box, and the leftover in the last box is your repair stock — worth keeping for the life of the floor.

Measure the floor, not the room

• Include closets if the flooring runs into them.
• Include doorways — flooring usually continues through to the transition strip.
• Deduct permanent fixtures only: an island with a toe kick, a hearth, a built-in cabinet run. Do not deduct appliances that sit on the floor.
• Break L-shapes into rectangles and add them. A single "average" measurement across an L-shaped room is always wrong.
• Measure each wall. Rooms are rarely square — use the longer figure of each opposing pair.

Coverage per Box by Flooring Type

Box coverage varies more than people expect, even within one product line. These are typical ranges — always use the figure on the box you are actually buying, which is why the calculator lets you type it in.

Carpet and sheet vinyl work differently. They come off a 12 ft or 15 ft wide roll, so your usable area depends on how the room fits that width — a 13 ft wide room off a 12 ft roll means a seam and significant offcut. Carpet is still often quoted per square yard: divide square feet by 9.

How Much Waste to Add

Waste is the number that separates a calculator you can trust from one you can't. It is not padding — it is the material that ends up as offcuts at the walls, at doorways, and around obstacles.

Two rules that override the table:

• Long narrow rooms need more, not less. A hallway has far more perimeter per square foot than a square room.
• Discontinued or clearance stock needs more. If you cannot buy one more box in six months, buy it now.

Which Flooring Should You Choose?

LVP has taken over the middle of the market for a reason: it is genuinely waterproof, it clicks together without adhesive, and it tolerates the moisture swings of a basement or bathroom that would destroy laminate or solid wood.

Solid hardwood is the only floor you can refinish repeatedly, which is why it outlives everything else here by decades. It is also the worst choice below grade or over a slab with moisture.

Costs above are material only. Professional installation typically adds $2–$6 per square foot, more for herringbone, stairs, or if there is old flooring to remove and dispose of.

What Else You Need to Buy

Flooring itself is usually 70–80% of the material bill. These are the items that get forgotten:

Do not skip the expansion gap. Floating floors expand and contract with humidity, and a floor butted tight to the wall will buckle. Leave 1/4 to 3/8 inch at every vertical surface and hide it under the baseboard or quarter round.

Check whether your planks have pre-attached underlayment before buying separate rolls — doubling it up voids many warranties and makes the floor feel spongy.

Planning the Layout

1. Acclimate the flooring. Leave the boxes flat in the room for 48–72 hours before installing. Wood and laminate move with the room's humidity, and installing cold or dry planks guarantees gaps later.
2. Check the subfloor is flat. Most manufacturers require flatness within 3/16 inch over 10 feet. Grind high spots, fill low ones with levelling compound.
3. Test a slab for moisture before laying anything over concrete — tape a 2 ft square of plastic down for 24 hours and look for condensation.
4. Run planks along the longest wall, or parallel to the main light source. It makes the room read longer and hides seams.
5. Measure the last row before you start. If it comes out under 2 inches wide, rip the first row narrower so both edges are balanced.
6. Mix planks from several boxes as you go. Colour and grain vary box to box, and blending prevents visible patches.
7. Stagger end joints by at least 6 inches — 8 to 12 is better. Repeating joints in a stair-step pattern is the most common amateur giveaway.
8. Undercut door casings rather than cutting the plank around them. It looks far better and is faster.

Mistakes to Avoid

• Ordering exactly what the math says. One damaged plank at the end of the job means another box, another dye lot, and a visible patch.
• Mixing dye lots. Buy every box in one purchase and check the lot numbers match.
• Laying over a damp slab. Moisture is the leading cause of floor failure over concrete.
• Skipping acclimation. Gaps in winter and buckling in summer both trace back to this.
• Nailing or gluing a floating floor down at thresholds or under heavy cabinets — it has to be free to move.

Frequently Asked Questions

How many boxes of flooring do I need?

Multiply your floor area by your waste factor, then divide by the coverage printed on the box and round up. A 180 sq ft room with 10% waste is 198 sq ft; at 20 sq ft per box that is 10 boxes. Always round up — you cannot buy part of a box.

How much extra flooring should I buy?

10% for a standard straight layout, 15% for diagonal installs or rooms with many corners, and 20% or more for herringbone and chevron. Solid hardwood needs about 15% because you are also cutting around natural defects.

How many square feet is a box of laminate flooring?

Typically 18 to 24 square feet, though it varies by manufacturer and plank size. Vinyl plank ranges wider still, from 18 to 30. Never assume — the coverage is printed on every box, and it is the single figure your whole order depends on.

Do I include closets and doorways in my flooring measurement?

Include closets if the flooring runs into them, and include doorways since flooring normally continues through to the transition strip. Deduct only permanent fixtures — an island with a toe kick, a hearth, a built-in cabinet run. Do not deduct appliances that simply sit on the floor.

How do I convert square feet to square yards for carpet?

Divide by 9. A square yard is 3 ft × 3 ft, so 180 square feet is 20 square yards. Carpet is still frequently quoted per square yard, which makes it look cheaper than it is — $30 a yard is $3.33 per square foot.

Do I need underlayment under laminate or vinyl plank?

Under floating floors, yes — it cushions, quiets, and evens out minor subfloor variation. But check whether your planks have it pre-attached first. Doubling up makes the floor feel spongy, stresses the locking joints, and voids many warranties. Over concrete you also need a 6-mil vapour barrier.

How long does flooring need to acclimate?

48 to 72 hours for most laminate, vinyl and engineered products, and longer for solid hardwood — some manufacturers ask for a week. Leave the boxes flat in the room where the floor will be installed, not in a garage. Skipping this causes gaps in winter and buckling in summer.

How flat does the subfloor need to be?

Most manufacturers require flatness within about 3/16 inch over 10 feet. Check with a long straightedge, grind down high spots, and fill low ones with levelling compound. A floating floor over an uneven subfloor flexes at the joints and eventually the locking mechanism fails.

Which direction should flooring run?

Along the longest wall, or parallel to the main light source from a window. Both make the room read longer and make seams less visible. On an upper floor, running planks perpendicular to the joists adds stiffness — worth doing if the two rules conflict.

How big should the expansion gap be?

1/4 to 3/8 inch at every wall and every vertical surface, including pipes and door casings. Floating floors expand and contract with humidity, and a floor butted tight to a wall will buckle. Baseboard or quarter round covers the gap.

Why do I need to buy all my flooring at once?

Because of dye lots. Flooring is produced in batches and colour varies measurably between them. A box bought three weeks later will often be visibly different, and there is no fixing it once the floor is down. Buy the full order together and check the lot numbers match.

Can I install flooring over existing flooring?

Often yes for floating floors, provided the existing surface is flat, sound, and dry. Vinyl plank and laminate go over old vinyl, tile, or well-adhered sheet goods without trouble. Do not float over carpet, over anything loose or cupped, or where the added height would foul a door or an appliance opening.