How to Measure a Room for Carpet

Q: What tools do I need to measure a room for carpet?

You need a 25-foot tape measure, a notepad and pen, a calculator, and a helper to hold the other end of the tape on longer walls. A laser distance measurer ($30-$50) is useful for large rooms. Always measure in feet, rounding up to the nearest half foot.

Q: How do I measure stairs for carpet?

For each stair, measure the tread depth (horizontal surface, typically 10-11 inches), the riser height (vertical face, typically 7-8 inches), and add 1 inch for the nose tuck. Multiply by the staircase width (typically 36 inches). A standard 13-step staircase needs about 55-65 sq ft of carpet, including 15% waste.

Q: Do I need to move furniture before measuring?

No, you do not need to move furniture to measure. Measure from wall to wall, not around furniture. The carpet will be installed wall to wall regardless of where furniture sits. However, all furniture will need to be removed or moved by the installer on installation day.

Accurate room measurements are the first step to a successful carpet installation. Whether you're measuring for a single bedroom or your entire house, this guide walks you through the exact process professional installers use. Follow these steps to avoid ordering too little (and delaying your project) or too much (and wasting money).

By Jordan Rivera|Updated Feb 26, 2026

Quick link: Already have your measurements? Use our free carpet calculator to instantly calculate how much carpet you need, including waste factor and cost estimates.

Tools You Need

25-foot tape measure — metal tape, not cloth (cloth stretches and gives inaccurate readings)
Notepad and pen — sketch each room as you measure
Calculator — or use your phone
A helper — holding the tape end on longer walls prevents sagging
Optional: Laser distance measurer ($30-$50) — faster and more accurate for large rooms

Step 1: Measure Length and Width

Start with the longest wall in the room. Place the tape measure flat on the floor against one wall and extend it to the opposite wall. Record the measurement in feet. Repeat for the other dimension (width). Always measure at the widest and longest points of the room.

Key rules:

Measure wall to wall, not baseboard to baseboard (carpet goes under the baseboard)
Round up to the nearest half foot (12 feet 3 inches = 12.5 feet)
If the walls aren't parallel, take the longest measurement
Do not measure around furniture — carpet installs wall to wall

Step 2: Calculate the Area

Multiply length by width to get square footage:

Area = Length × Width
Example: 12 ft × 15 ft = 180 square feet

Step 3: Measure Closets Separately

Each closet is measured as its own rectangle. Measure the depth (front to back) and the width (side to side) of the closet interior. Add this to your room total.

Closet Type	Typical Size	Square Feet
Standard reach-in closet	2 ft × 6 ft	12 sq ft
Double reach-in closet	2 ft × 10 ft	20 sq ft
Small walk-in closet	5 ft × 5 ft	25 sq ft
Large walk-in closet	6 ft × 8 ft	48 sq ft

Step 4: Measure Irregular Rooms

L-Shaped Rooms

Divide the room into two rectangles. Measure each rectangle separately, then add them together. For example, an L-shaped living room might break into a 12×15 section (180 sq ft) and a 6×8 section (48 sq ft) = 228 sq ft total.

Rooms with Bay Windows or Alcoves

Measure the main room as a rectangle, then add the bay window or alcove area separately. Bay windows typically add 10-20 sq ft. Always measure to the furthest point of the bay.

Rooms with Angled Walls

Measure the room as if the angled wall were a full rectangle (use the longest length and widest width). You'll have extra carpet from the angle, but this approach ensures you have enough material and the excess is covered by the waste factor.

Step 5: Measure Stairs

Stairs are measured differently from flat rooms. For each step, you need three measurements:

Tread depth (horizontal surface where you step) — typically 10-11 inches
Riser height (vertical face between steps) — typically 7-8 inches
Nose tuck — add 1 inch for the carpet that tucks under the nose of each tread

Per-step calculation: (tread + riser + 1 inch) × staircase width

Example: (10" + 7.5" + 1") = 18.5 inches per step × 36 inch wide staircase = 666 sq inches = 4.6 sq ft per step. For 13 steps: 4.6 × 13 = 60 sq ft. Add 15% waste: 60 × 1.15 = 69 sq ft of carpet for the staircase.

Step 6: Add the Waste Factor

Always order more carpet than the exact measured area to account for cutting waste, seam matching, and installation errors:

Room Type	Waste Factor	Why
Simple rectangle	5-10%	Minimal cutting, no seams needed
Standard room with closet	10%	Some cutting around door frame and closet opening
L-shaped or irregular room	15%	More cutting, possible seam needed
Stairs	15%	Many small cuts, precise fitting needed
Patterned carpet	15-20%	Patterns must align at seams, creating extra waste

Step 7: Whole-House Measurement Checklist

If you're carpeting multiple rooms, use this checklist to make sure you don't miss anything:

All bedrooms (including closets)
Master bedroom (including walk-in closet)
Living room / family room
Hallways (length × width for each section)
Stairs (number of steps × per-step area)
Landing at top/bottom of stairs
Den or bonus room
Walk-in closets (measured separately)

Add each room's total area together, then enter the total into our carpet calculator to get your final estimate with waste factor and cost.

Common Measurement Mistakes to Avoid

Measuring baseboard to baseboard instead of wall to wall — carpet tucks under the baseboard, so you need wall-to-wall measurements
Forgetting closets — closets add 12-50 sq ft each and are easy to overlook
Rounding down — always round up to the nearest half foot
Using a cloth tape measure — cloth stretches and gives inaccurate readings; use a metal tape measure
Skipping the waste factor — without waste factor, you'll likely run short during installation
Measuring around furniture — carpet installs wall to wall; measure as if the room were empty

Frequently Asked Questions

What tools do I need to measure a room for carpet?

You need a 25-foot metal tape measure, a notepad and pen for sketching, a calculator, and ideally a helper to hold the other end of the tape on longer walls. A laser distance measurer ($30-$50) makes the job faster and more accurate for large rooms. Always measure in feet and round up to the nearest half foot.

Should I include closets when measuring for carpet?

Yes, include all closets that will be carpeted. Measure each closet as a separate rectangle (depth × width) and add it to the room's total square footage. Walk-in closets should be measured like a small room. Most installers recommend carpeting closets with the same material for a seamless look, so include closet square footage in your total.

How do I measure stairs for carpet?

For each stair step, measure the tread depth (horizontal surface, typically 10-11 inches), the riser height (vertical face, typically 7-8 inches), and add 1 inch for the nose tuck. Multiply the total per step by the staircase width (typically 36 inches). A standard 13-step staircase needs about 55-65 sq ft of carpet, plus 15% waste for a total of about 65-75 sq ft.

Do I need to move furniture before measuring?

No, you don't need to move furniture to measure. Measure from wall to wall, not around furniture. The carpet will be installed wall to wall regardless of where furniture sits. However, all furniture will need to be removed or moved by the installer (or you) on installation day — discuss this with your installer in advance.

How accurate do my carpet measurements need to be?

Measure to the nearest half foot and always round up. The 10-15% waste factor built into carpet estimates provides a buffer for small measurement errors. Being off by a few inches is fine because the waste factor covers it, but being off by a foot or more on a large room can mean not enough carpet. If in doubt, measure twice and use the larger number.