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Carpet Roll Length & Waste Calculator

Calculate the length of broadloom carpet needed from a standard roll width, including seaming and pattern-match waste.

  • Answers as you type
  • Every formula cited
  • Calculated in your browser
SettingsSettings for this calculationUS
Market
Imperial · sales tax
Who is doing the work?

The standard allowance most suppliers and estimating guides assume for ordinary work.

The total floor area to be carpeted.

Measure the room's length x width, or add up multiple sections for an irregular area.

The width of the broadloom carpet roll.

Common broadloom widths include 3.66m (12 ft) and 3.05m (10 ft) — check your specific product.

Extra carpet length for seaming, pattern matching, and pile direction.

10% is a common starting point for a simple rectangular room; patterned carpet or rooms needing multiple seams often need a higher allowance.

Carpet roll length needed

20.2 ft

Medium confidence

Rooms wider than the roll width require seaming, which adds waste beyond this base estimate — for rooms requiring multiple carpet widths, consult an installer for exact seam placement and cut-length waste.

Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

  • Roll length needed = (room area × (1 + waste allowance)) ÷ standard roll width, accounting for seaming, pattern matching, and pile direction waste

Inputs used

Room Area
220 sq ft
Standard Roll Width
12 ft
Waste Allowance (%)
10
Final result20.17 ft

Confidence note: Rooms wider than the roll width require seaming, which adds waste beyond this base estimate — for rooms requiring multiple carpet widths, consult an installer for exact seam placement and cut-length waste.

What this calculation does not cover

  • A pattern repeat is not a percentage. Every drop has to start at the same point in the pattern, so each one is cut up to a whole repeat longer than the piece it covers, and the waste grows with the size of the repeat and the number of drops rather than with floor area — a large repeat in a room needing four drops will beat any allowance entered here.
  • This is the carpet and only the carpet. Underlay comes on its own, narrower roll and has to be figured against its own width, and gripper is bought against the perimeter rather than the area — they go on the same order and only one of them is on this page.
  • Stairs never come out of an area calculation. Each step takes the riser plus the tread plus enough to wrap the nosing, cut as one continuous length for the flight so the pile runs the same way down it, and winders or a half-landing add more again — count a stair on its own and add it to the length above.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

14.83 ft4.52 m14.83 ft4.52 mequivalent area220 sq ft20.44 m²5 ft2 m

Part of bigger jobs

This trade is one line of a job takeoff. Run the whole job and every other trade comes back with it, off the same measurements.

Or plan the space itself: measure it once, doors and windows included, and this figure comes back worked out on that space, with what goes with it.

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-09-06 · in the site-wide review of 2026-09-06 · v1.1.1

Regulatory standards & verification citations1
  1. Roll length needed = (room area × (1 + waste allowance)) ÷ standard roll width, accounting for seaming, pattern matching, and pile direction waste
Cite this page

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Tools and safety for this job

To lay carpet. Generic types, no brands, no prices.

Protection this work requires

  • Boards, blocks and bagged material cause most lasting back injuries on small sites: two people or a lifter for full sheets, and never a bag on one shoulder up a ladder.
  • Knives cause more site injuries than any power tool: cut away from your body, change blades often, and wear cut-resistant gloves to EN 388 level C for repeated cutting.
Show the 5 tools this job needs

Essential

  • Carpet trimmer and tucking tool

  • Knee kicker and carpet stretcher

  • Tape measure

  • Utility knife

Recommended

  • Claw hammer

Also needed as materials: replacement blades.

what each flooring tool is for, and the spec that decides which to buy where one does.

Now that you have the number

These guides cover the work this quantity is for — the first ones run this calculator inside the section that raises the question.

  • Laying Carpet and Carpet Tileuses this calculator

    Broadloom arrives at a fixed width, so seam placement — not room area — drives every carpet and carpet-tile decision on site.

Still deciding? Carpet Tile vs Broadloom · Carpet vs Vinyl Plank — the factors that actually differ, with no invented prices.

The data behind it: Production rates by operation

How to calculate carpet roll length & waste in 4 steps

  1. Room AreaThe total floor area to be carpeted.
  2. Standard Roll WidthThe width of the broadloom carpet roll.
  3. Waste Allowance (%)Extra carpet length for seaming, pattern matching, and pile direction.
  4. Carpet roll length neededThe tool computes the carpet roll length needed from those figures and shows the formula, its sources, and a confidence rating alongside it.

Carpet roll length needed by room area

Page defaults, not your figures above.

Room AreaCarpet roll length needed (ft)
100 sq ft9.16
150 sq ft13.7
200 sq ft18.3
250 sq ft22.9
300 sq ft27.5
350 sq ft32.1
400 sq ft36.6

Frequently asked questions

Why does this divide by the roll width?
Broadloom carpet is sold as a continuous roll of fixed width — since only the room area needs covering, dividing the (waste-adjusted) area by the roll's width converts that area into the length of roll you need to order.
Does this account for pattern matching?
Only loosely, through the waste allowance percentage — carpets with a strong repeating pattern typically need a higher waste allowance than plain or textured carpet to line up the pattern across seams.
What if my room is wider than the roll?
Then it takes whole drops, widths of carpet laid side by side, each cut the room's full length. Dividing the floor area by the roll width under-counts them, because the last drop is bought at full width however little of it the room uses. Count the drops (the room's width divided by the roll width, rounded up) and enter drops × roll width × room length as the area: the width divides back out and the answer is the drops end to end plus the waste allowance. The Carpet and cushion takeoff does exactly that. Seam placement, pile direction and a pattern repeat can still move the cuts, and an installer's seam plan is the final word.
Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.