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Carpet & Padding Calculator

Estimate broadloom carpet rolls, underlayment padding area, square yards/meters, and material budget.

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Reviewed by Tariq Al-Mansoor, Senior Construction Estimator & QS (15+ yrs exp) Verified against ISO 80000 & ASTM building measurement standards

Your estimate

Enter measurements, then calculate.

Planning estimate only. Confirm packaging, coverage, site conditions, and local building requirements before purchasing.

Measurement Schematic Visual guide for dimensions & layout

How to measure

Measure room length and width across the widest points, including door entryways.
Confirm commercial carpet roll width (standard: 12 ft / 3.66 m or 13.1 ft / 4.0 m).
Ensure all strips run with carpet pile oriented in the same direction to prevent visible shading.
Add a 10% waste allowance for roll drops, seam alignment, and wall trimming.

Input guide

Enter room length and width in meters or feet.
Input standard roll width in meters (default: 4.0 m) or feet (default: 12 ft).
Apply a 10% waste allowance for seaming and wall perimeter trimming.
Enter price per square meter or square yard to calculate total carpet budget.

Formula

Carpet Area = Ceiling( Room Width ÷ Roll Width ) × Roll Width × Room Length × (1 + Waste)

The calculator determines the number of full-width roll cuts needed to span the room width.

Linear carpet length is multiplied by fixed roll width to calculate commercial ordered area.

Outputs return square meters (m²) for metric or square yards (yd²) for imperial projects.

Worked example: Master bedroom plush carpet installation

A bedroom measuring 5.0 m length by 3.5 m width equals 17.5 m² of floor area.
Using a standard 4.0 m roll width, 1 roll drop spans the 3.5 m width completely.
Ordered length = 5.0 m × 1.10 waste = 5.5 m linear run.
Total carpet area ordered = 1 drop × 4.0 m roll width × 5.5 m length = 22.0 m².

At 30 USD per m² (or ~25 USD/yd²), estimated carpet cost is 660 USD for 22.0 m².

Buying advice

Order high-density underlayment cushion padding (e.g., 8 lb/cu ft / 10 mm) to extend carpet life.
Budget for perimeter tackless gripper strips and heat-bond seaming tape.
Position seams away from high-traffic doorways and direct window light whenever possible.

Common mistakes

Mixing carpet pieces with opposing pile directions, creating severe color shading lines.
Using cheap low-density padding that compresses permanently within months.
Not power-stretching carpet during installation, leading to loose ripples and buckles.
Measuring only inside baseboards without adding 7.5 cm (3 in) wall trimming excess.

Roll width layout and pile direction

Broadloom carpet is typically supplied in fixed rolls of 12 ft (3.66 m) or 13.1 ft (4.0 m) widths. Carpet must always be installed with the pile fibers facing in the same direction throughout adjacent spaces to prevent color mismatch shading.

Cross-seams should be positioned away from primary doorways and direct natural light sources whenever practical.

Carpet padding and installation checklist

Order carpet cushion padding with equal square footage to the room plus 5% waste.
Choose a high-density rebond underlayment (e.g., 7/16 in thickness with 8 lb/cu ft density) for maximum durability underfoot.
Budget for perimeter tackless gripper strips (installed 1/4 in from walls) and heat-bond seaming tape for all joins.
Add 3 inches (7.5 cm) of excess length to every roll cut for trimming against walls.
For stair installations, add 1 linear foot of carpet per stair step to account for tread and riser wrap.

Moisture, stretching, and commercial limits

Carpet must be mechanically power-stretched during installation to prevent rippling and premature delamination.

This tool estimates residential broadloom roll areas. It does not calculate glue-down commercial carpet tile modules, radiant heated subfloor thermal ratings, or industrial static dissipative flooring.

Frequently asked questions

How is carpet measured for purchasing?

In the US, carpet is sold by the square yard (9 sq ft); in metric regions, by the square meter.

What density should carpet padding be?

An 8 lb/cu ft (100–120 kg/m³) density underlayment offers the best durability and comfort.

Why is broadloom carpet area larger than room area?

Carpet comes in fixed 12ft/4m roll widths, creating unused roll drop offcuts on narrow rooms.

Can carpet be installed on concrete subfloors?

Yes, using tackless gripper strips fastened with masonry nails and moisture-resistant padding.