How many square yards of carpet do I need for a 12 by 15 ft room?

The floor is 180 sq ft, which is 20 sq yd. On a 12 ft roll that is also the order: the 12 ft side lies across the roll, so one strip 15 ft long covers the room, there is no seam and there is no waste. A 13 by 14 ft room has only 2 sq ft more floor, but neither side fits a 12 ft roll, so it takes two strips, one seam and 312 sq ft of carpet. That is why the area on its own never settles the question.

Why does a 13 ft wide room need so much more carpet than a 12 ft one?

A 13 by 15 ft room on a 12 ft roll needs two strips. Best fit runs two 13 ft strips across the width: 26 linear ft, 312 sq ft or exactly 104/3 sq yd, with one seam and 117 sq ft waste. Forced along the length uses two 15 ft strips, or 30 linear ft. The best-fit layout leaves a 9 ft side offcut in the last strip. Purchasing readouts round nonterminating quantities upward and label that bound; the exact report retains the full fraction. A 15 ft roll covers this room with one strip: 13 linear ft, no seam and no waste.

What widths does carpet come in?

The five supplied-width buttons set 12 ft, 13 ft 6 in, 15 ft, 4 m and 5 m. Enter the actual usable width your supplier quotes; no arbitrary physical roll-width cap is imposed. Room, roll and repeat each have their own unit, and explicit ft, in, m, cm, mm or yd suffixes carry their stated physical meaning. Feet and inches such as 12 feet 6 inches are accepted. Unit switches convert the current physical values exactly; invalid or incomplete drafts stay unchanged.

How much waste should I allow on top?

The waste figure is purchased full-width carpet minus rectangular floor area; side offcuts and pattern-repeat rounding are already included. The allowance opens at zero and only adds your supplied percentage, from 0 to 100, to the total roll run. It does not infer a trimming margin at each edge, shrinkage or the condition of a room. Ask your supplier or fitter for any allowance the actual job needs.

What does a pattern repeat do to the order?

Each strip length rounds up to the next whole supplied repeat. For the best-fit 13 by 15 ft room on a 12 ft roll, an 18 in repeat turns each 13 ft strip into 13.5 ft: 27 linear ft or 36 sq yd. An exact multiple adds nothing, while any positive partial repeat needs the next whole repeat. This is a quantity model. It does not establish starting pattern offsets, alignment across seams, pile direction, trimming or a complete fitting plan.

Can it do an L-shaped room, a closet or stairs?

This calculator covers one rectangular room with straight strips from one roll. L-shapes, closets combined with a room, stairs, multiple-room or whole-house plans and carpet-tile counts need other workflows. It does not nest or reuse offcuts, so a usable remnant still counts as waste in this model. It does not certify property, built-up or legal carpet-area definitions.

Does the cost figure include fitting?

The supplied price applies to purchased carpet only, per square yard, square foot, square metre, linear foot or linear metre of roll. Cost uses the exact quantity and rounds once to two decimal places, nearest with halves upward. Currency is whatever currency you supplied. It does not include installation, underlay, gripper, removal, cleaning, delivery, tax, market prices or quotes.

Carpet Calculator

A square yard figure for the floor is not the order. Carpet comes off a roll of a fixed width, it is sold by the full width of that roll, and the moment a room is wider than the roll there is a seam and an offcut. Here the roll width is an input, the strips are laid out both ways round so you can see which direction buys less, and the run, the seams, the offcut and the waste are four separate numbers rather than one padded total. A pattern repeat cuts every strip to a whole number of repeats, which is the part that makes a patterned carpet cost more than its area suggests. The calculation uses exact represented decimals and fractions, with strict whole-strip and whole-repeat ceilings. A repeat estimates quantity without guaranteeing pattern alignment or fitting. Explicit units retain their physical meaning, and unit switches convert room, roll and repeat measurements. Purchasing displays use exact values or marked upward-rounded bounds; the complete report retains exact quantities, supplied values and assumptions.

Room not measured yetRoll 12Pattern as suppliedAllowance 0%

Enter the room width and length. The strips, seams and roll length appear here.

A 12 by 15 ft room on a 12 ft roll needs one 15 ft run with no seam. Enter your own room measurements below.

Room area: ?

Carpet, sq yd: ?

Roll runs: ?

Waste: ?

Length to buy: ?

Seams: ?

The room

One rectangle, measured wall to wall. Feet and inches such as 12′ 6″, explicit ft/in/m/cm/mm/yd suffixes, fractions, mixed numbers, scientific notation and commas grouping thousands retain their physical meaning. Unit changes convert supplied measurements; invalid drafts stay unchanged.

Room widthRoom lengthMeasured in

The roll and the strips

Best fit compares both exact roll runs and chooses the shorter; equal runs prefer fewer seams, then along the length. Supply the direction when pile direction matters. Every positive partial strip needs the next whole strip.

Roll widthRoll measured in

Widths carpet is sold in

Strip direction

Pattern repeat, optionalRepeat measured in

The optional repeat rounds each strip up to a whole number of supplied repeats. It estimates quantity; it does not establish pattern starting offsets, seam matching, trimming or a complete fitting plan.

Allowance and price

Waste already includes the full-width roll offcut. A supplied allowance from 0 to 100 percent adds to the total run. Supply a carpet-only price in your currency for the selected basis; installation, underlay, delivery and tax are excluded.

Allowance, percentPrice, optionalPriced per

Purchasing readouts show exact terminating values or marked upward-rounded bounds. Tiny positive quantities remain nonzero; shortened values refer to the exact complete report. Numbers accept up to 8192 characters, 512 significant digits per component and normalized decimal scales from -4096 to 4096. There is no physical room, roll-width, repeat, strip-count or price cap. The diagram is omitted above 64 strips or when the aspect ratio is too thin to draw clearly; the complete quantities remain available.

Worked examples

Each one uses the same exact function. Load it, then change a measurement to make it yours.

12 by 15 ft, 12 ft rollone run, no seam
15 ft of roll, 1 runs, 0 seams, 20 sq yd
13 ft wide roomsame 12 ft roll
26 ft of roll, 2 runs, 1 seams, 34.67 (rounded up) sq yd
Pattern repeat 18"the same 13 ft room
27 ft of roll, 2 runs, 1 seams, 36 sq yd

Complete selectable report

Quantity and layout, not fitting. Exact represented decimal and rational arithmetic for one rectangle and straight strips from one roll. The diagram is illustrative; the textual quantities are complete. Offcuts are not reused. Stairs, multiple rooms, L-shapes, carpet tiles, underlay, adhesive, fitting and market prices are excluded.

Common questions

How many square yards of carpet do I need for a 12 by 15 ft room?: The floor is 180 sq ft, which is 20 sq yd. On a 12 ft roll that is also the order: the 12 ft side lies across the roll, so one strip 15 ft long covers the room, there is no seam and there is no waste. A 13 by 14 ft room has only 2 sq ft more floor, but neither side fits a 12 ft roll, so it takes two strips, one seam and 312 sq ft of carpet. That is why the area on its own never settles the question.
Why does a 13 ft wide room need so much more carpet than a 12 ft one?: A 13 by 15 ft room on a 12 ft roll needs two strips. Best fit runs two 13 ft strips across the width: 26 linear ft, 312 sq ft or exactly 104/3 sq yd, with one seam and 117 sq ft waste. Forced along the length uses two 15 ft strips, or 30 linear ft. The best-fit layout leaves a 9 ft side offcut in the last strip. Purchasing readouts round nonterminating quantities upward and label that bound; the exact report retains the full fraction. A 15 ft roll covers this room with one strip: 13 linear ft, no seam and no waste.
What widths does carpet come in?: The five supplied-width buttons set 12 ft, 13 ft 6 in, 15 ft, 4 m and 5 m. Enter the actual usable width your supplier quotes; no arbitrary physical roll-width cap is imposed. Room, roll and repeat each have their own unit, and explicit ft, in, m, cm, mm or yd suffixes carry their stated physical meaning. Feet and inches such as 12 feet 6 inches are accepted. Unit switches convert the current physical values exactly; invalid or incomplete drafts stay unchanged.
How much waste should I allow on top?: The waste figure is purchased full-width carpet minus rectangular floor area; side offcuts and pattern-repeat rounding are already included. The allowance opens at zero and only adds your supplied percentage, from 0 to 100, to the total roll run. It does not infer a trimming margin at each edge, shrinkage or the condition of a room. Ask your supplier or fitter for any allowance the actual job needs.
What does a pattern repeat do to the order?: Each strip length rounds up to the next whole supplied repeat. For the best-fit 13 by 15 ft room on a 12 ft roll, an 18 in repeat turns each 13 ft strip into 13.5 ft: 27 linear ft or 36 sq yd. An exact multiple adds nothing, while any positive partial repeat needs the next whole repeat. This is a quantity model. It does not establish starting pattern offsets, alignment across seams, pile direction, trimming or a complete fitting plan.
Can it do an L-shaped room, a closet or stairs?: This calculator covers one rectangular room with straight strips from one roll. L-shapes, closets combined with a room, stairs, multiple-room or whole-house plans and carpet-tile counts need other workflows. It does not nest or reuse offcuts, so a usable remnant still counts as waste in this model. It does not certify property, built-up or legal carpet-area definitions.
Does the cost figure include fitting?: The supplied price applies to purchased carpet only, per square yard, square foot, square metre, linear foot or linear metre of roll. Cost uses the exact quantity and rounds once to two decimal places, nearest with halves upward. Currency is whatever currency you supplied. It does not include installation, underlay, gripper, removal, cleaning, delivery, tax, market prices or quotes.

Exact arithmetic on the room and roll you enter. It assumes rectangular rooms and straight runs; it does not plan seam placement for you.