How to Calculate Area of a Room (Square Feet & Square Meters)

Whether you're buying flooring, painting walls, renting an apartment, or just curious how big your room actually is — knowing how to calculate room area is a fundamental life skill. It takes 2 minutes with a tape measure and basic multiplication.

Use the CalcHub Area Calculator for instant calculations.

Rectangular Rooms (Most Common)

Area = Length × Width

Room	Length	Width	Area (sq ft)	Area (sq m)
Small bedroom	10 ft	12 ft	120 sq ft	11.1 m²
Master bedroom	14 ft	16 ft	224 sq ft	20.8 m²
Living room	15 ft	20 ft	300 sq ft	27.9 m²
Kitchen	10 ft	8 ft	80 sq ft	7.4 m²
Bathroom	6 ft	8 ft	48 sq ft	4.5 m²

Step-by-Step Guide

Step 1: Measure Length

Use a tape measure along the longest wall, from one inside corner to the other. Measure at floor level — walls may not be perfectly straight higher up.

Step 2: Measure Width

Measure the shorter wall, perpendicular to the first measurement.

Step 3: Handle Inches

If your room is 12 feet 6 inches wide, convert: 6 inches = 0.5 feet. So width = 12.5 feet.

Inches	As Feet (Decimal)
3"	0.25 ft
4"	0.33 ft
6"	0.50 ft
8"	0.67 ft
9"	0.75 ft
10"	0.83 ft

Step 4: Multiply

12.5 ft × 14 ft = 175 sq ft

Step 5: Convert (if needed)

To square meters: 175 × 0.0929 = 16.26 m² To square yards: 175 ÷ 9 = 19.44 sq yd

L-Shaped Rooms

Split into two rectangles, calculate each, and add:

┌──────────────┐
│    A (10×8)  │
│              ├────────┐
│              │ B (6×5)│
└──────────────┴────────┘

• Rectangle A: 10 × 8 = 80 sq ft
• Rectangle B: 6 × 5 = 30 sq ft
• Total: 110 sq ft

Rooms with Alcoves or Bay Windows

1. Measure the main rectangle: 14 × 12 = 168 sq ft
2. Measure the alcove: 4 × 3 = 12 sq ft
3. Add them: 168 + 12 = 180 sq ft

Rooms with Pillars or Cutouts

1. Calculate full room area: 16 × 14 = 224 sq ft
2. Calculate pillar/cutout area: 2 × 2 = 4 sq ft
3. Subtract: 224 − 4 = 220 sq ft

Wall Area (for Painting)

Wall area = Perimeter × Ceiling height − Openings

Room: 12 × 14 ft, ceiling 10 ft, 2 windows (3×4 ft each), 1 door (3×7 ft)

1. Perimeter = 2×(12+14) = 52 ft
2. Gross wall area = 52 × 10 = 520 sq ft
3. Windows = 2 × (3×4) = 24 sq ft
4. Door = 3 × 7 = 21 sq ft
5. Net paintable area = 520 − 24 − 21 = 475 sq ft

At 350 sq ft/gallon: 475 ÷ 350 = 1.36 gallons per coat. For 2 coats: ~3 gallons.

Ceiling Area

Ceiling area = floor area (for flat ceilings). Same 12 × 14 = 168 sq ft.

For vaulted ceilings, the area is larger — you need to account for the slant. Measure the slant length instead of the flat width.

Common Room Sizes in India

Room Type	Carpet Area (sq ft)	Super Built-Up (sq ft)
1 BHK apartment	350–500	500–700
2 BHK apartment	550–850	800–1,200
3 BHK apartment	900–1,400	1,200–1,800
Independent house (floor)	800–2,000	—

Remember: Real estate in India quotes super built-up area (includes walls, lobbies, staircase share). Actual usable (carpet) area is 65–75% of super built-up.

Quick Estimation Without Measuring

No tape measure? Use these approximations:

• Floor tiles: Count tiles in one row × tiles in perpendicular row × tile size

- Standard tile: 2×2 ft = 4 sq ft per tile
- 12 tiles × 10 tiles × 4 = 480 sq ft

• Pacing: One adult step ≈ 2.5 feet. 5 steps × 6 steps × (2.5)² = 187.5 sq ft


• Arm span: Average adult arm span ≈ 5.5 feet

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What's the difference between carpet area and built-up area?

Carpet area = floor you can lay carpet on (walls excluded). Built-up area = carpet + wall thickness + balcony. Super built-up = built-up + share of lobby, stairs, elevator. Carpet is typically 65–75% of super built-up.

How do I measure an irregular room?

Break it into simple shapes (rectangles, triangles). Measure each shape independently, calculate their areas, and add them together. For curves, approximate with triangles or use the formula for circles/semicircles.

Is there an app to measure room area?

Most smartphones have a built-in "Measure" app (iOS) or equivalent (Android) that uses AR to estimate room dimensions. They're roughly accurate (±5%) for quick estimates but not precise enough for flooring orders or construction.

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Related Calculators

• Square Footage Calculator — any shape
• Paint Calculator — how much paint to buy
• Tile Calculator — tiles needed for your floor
• Area Converter — sq ft ↔ sq m ↔ acres