Estimate flooring sqft with install-pattern waste, boxes by SKU coverage, carpet roll length, underlayment rolls and transition strips.
Inches accept fractions: 12 5/8, 12-5/8, or 12.625
| Item | Quantity |
|---|---|
| Underlayment rolls (100 sqft each) | 2 |
| Transition strips (one per doorway) | 3 |
| Quarter-round / shoe molding (8 ft pieces) | 0 |
Advanced · waste override · underlayment · doorways · molding
Reverse: how much area can N boxes cover?
Enter a box count and your install pattern — see the project sqft you can finish (after waste).
How the math works
Flooring orders are area work with two adjustments most calculators skip: a pattern-driven waste margin and a box-coverage rounding step that is set by the SKU you actually buy.
- Sum every room:
project_sqft = Σ length × width - Add waste based on install pattern:
buy_sqft = project_sqft × (1 + waste%) - Round up to whole boxes:
boxes = ceil(buy_sqft / box_coverage_sqft) - Note what you have left:
extra_sqft = boxes × box_coverage − buy_sqft
For broadloom carpet and sheet vinyl the box step disappears — substitute roll width for box coverage and you get linear feet of roll instead.
Coverage reference — typical sqft per box
| Material | Default sqft / box | Range across SKUs |
|---|---|---|
| Laminate | 20 | 18–24 |
| LVP / LVT (luxury vinyl) | 24 | 18–30 |
| Engineered hardwood | 25 | 22–28 |
| Solid hardwood (3¼″ strip) | 22 | 18–25 |
| Carpet tile (24″ × 24″) | 54 per carton | 48–60 |
| Vinyl sheet | roll, 6 / 12 ft wide | — |
| Carpet broadloom | roll, 12 / 13.5 / 15 ft wide | — |
The defaults match what Pergo, Mohawk, Shaw, Mannington and Armstrong print on their cartons in 2025–2026, but every SKU is different — read the actual carton and override the default box coverage. That field is the single most common source of “I came up short” on flooring jobs.
Install pattern → waste margin
| Pattern | Waste margin | Why |
|---|---|---|
| Straight (parallel to longest wall) | 7–10% | End-cuts on each row; one cut per row reused as starter |
| Diagonal (45°) | 15% | Both ends of every row are angle-cuts that can’t always be re-used |
| Herringbone / chevron | 20% | Every plank gets mitred; offcuts rarely fit anywhere |
| Many small rooms / closets | 15% | Each doorway and closet adds a fresh starter row |
10% is the residential default for straight-laid laminate, LVP and hardwood under 1000 sqft. Bump higher only if the pattern, room geometry, or installer experience justifies it — paying for an extra 5% you don’t use is cheaper than a second store trip a week later, but a blanket 20% on a straight LVP bedroom is just lost money.
Worked example — 16×20 living room, laminate, straight pattern
- Project area:
16 × 20 = 320 sqft - Waste at 10% (straight pattern):
320 × 1.10 = 352 sqft to buy - Boxes at 20 sqft / box:
ceil(352 / 20) = ceil(17.6) = 18 boxes - Coverage from 18 boxes:
18 × 20 = 360 sqft - Extra after the cut waste is consumed:
360 − 352 = 8 sqft— about half a box, not enough for a future repair
That last step is why the calculator flags “consider +1 box”: 8 sqft is enough to redo a small section of damaged planks once, but a full board replacement under a refrigerator three years later will need a same-lot match, which is the kind of plank you cannot buy back.
Common questions
Why buy an extra box on top of the waste %?
Two reasons. First, future repairs: a leaky dishwasher, a dropped iron, a chair leg gouge — all happen years after install, when the same SKU on the shelf is from a different dye-lot or production run, and the seam between old and new will be visible under daylight. Second, lot consistency on day one: laminate and LVP printed wood-grain patterns drift slightly between batches, so anything beyond a single batch can show banding across a long living-room run. The “extra box for repairs” rule of thumb costs $30–80 and saves a future $400–1200 reorder of a discontinued SKU.
How many transition strips do I need?
One per doorway, plus one wherever two flooring materials meet (LVP-to-tile in a kitchen entry, carpet-to-hardwood at the bedroom threshold, etc.). Standard length is 36–48 inches; most doorways are 32–36 inches wide so a single strip covers each. T-moulds for same-height transitions, reducer strips for height changes (e.g. ⅜″ engineered to ⅛″ vinyl), and end caps where flooring meets a sliding door track.
Do I need an underlayment moisture barrier?
On a concrete subfloor — yes, almost always. Concrete wicks moisture for years after pour and laminate / engineered hardwood will cup or delaminate without a 6-mil polyethylene barrier (often built into combination foam-and-poly underlayments). On a wood subfloor (plywood or OSB over joists), a vapour barrier is usually unnecessary and can actually trap moisture against the subfloor — use a plain foam underlayment for sound dampening only. LVP and many modern laminates ship with attached pad — using a separate underlayment over them voids the warranty.
For a one-way conversion of carpet broadloom quotes between square feet and square yards (carpet is often priced per yd² in North America), the square feet to square yards converter handles the unit shift in one step. If your project includes a poured concrete subfloor pad, the concrete calculator sizes the pour and bag count.
Estimator only. Use this widget to size the trip to the supplier — order from the carton label, not from a calculator. SKU coverage varies by ±15% across product lines, doorway and molding counts come from your floor plan, and any pattern more complex than a parallel layout deserves a 1–2% safety bump on top of the table above.
