Area Calculator

Calculate Area of Any Shape Instantly

Imagine planning to install new flooring in your living room, but you're not sure how many square feet of material to buy. You know the room is 15 feet long and 12 feet wide, but converting that to square footage, adding waste allowance, and comparing prices per square foot feels overwhelming. Or you're landscaping your backyard—you have a circular garden bed with a 6-foot radius and need to know how much mulch to order, but the formula for circle area (πr²) is foggy from high school math class. These everyday situations require area calculations, but most people don't want to pull out formulas, do manual math, or risk making expensive mistakes.

Our Area Calculator eliminates the guesswork and math stress. Select your shape from 15+ options (rectangle, circle, triangle, trapezoid, irregular polygon, and more). Enter your measurements in any unit—feet, meters, inches, yards—whatever is convenient. Get instant results with automatic conversion to square feet, square meters, acres, hectares, or any unit you need. See visual diagrams showing exactly what measurements you need to take. Understand the formula being used with clear explanations. Save multiple calculations for complex projects. Export reports to share with contractors or keep for records. Whether you're a homeowner planning renovations, a student learning geometry, a contractor bidding jobs, or a gardener designing landscapes, this tool makes area calculations fast, accurate, and stress-free. No math degree required—just enter measurements and get professional results instantly.

Advanced Area Calculator Features

Area Formulas for Common Shapes

Understanding area formulas helps you measure correctly and verify calculator results. Here are the formulas for the most common shapes:

Rectangle & Square

Circle & Ellipse

Triangles

Trapezoid & Parallelogram

Regular Polygons

For shapes with equal sides (pentagon, hexagon, octagon): Area = (Perimeter × Apothem) ÷ 2. The apothem is the distance from center to the middle of any side. Our calculator handles these automatically—just enter the side length and number of sides.

Real-World Area Calculation Uses

Area Unit Conversion Reference

Our calculator automatically converts between all these units, but understanding the relationships helps you work with different measurement systems:

Common Area Unit Conversions

Quick Reference: Standard Sizes

• 1 Acre: 43,560 square feet (about 208.7 × 208.7 feet, or roughly a football field)
• 1 Hectare: 10,000 square meters or 2.47 acres
• 1 Square Mile: 640 acres or 2.59 square kilometers
• Average Room: 150-300 sq ft (bedroom), 200-400 sq ft (living room)
• Average House: 1,500-2,500 sq ft (varies widely by region)
• Tennis Court: 2,808 sq ft (78 ft × 36 ft for doubles)
• Basketball Court: 4,700 sq ft (94 ft × 50 ft)

Step-by-Step Calculation Examples

Example 1: Flooring for Living Room

Scenario: You need to buy hardwood flooring for a 18ft × 14ft living room. Flooring costs $4.50 per square foot, and you need 10% extra for waste.

Calculation:

• Step 1: Calculate base area: 18 × 14 = 252 square feet
• Step 2: Add 10% waste allowance: 252 × 1.10 = 277.2 square feet
• Step 3: Calculate cost: 277.2 × $4.50 = $1,247.40
• Result: Order 278 square feet of flooring, budget approximately $1,250

Example 2: Circular Garden Bed

Scenario: You're creating a circular flower bed with a 6-foot radius. Mulch covers 100 sq ft per bag at $5 per bag.

Calculation:

• Step 1: Calculate circle area: π × 6² = 3.14159 × 36 = 113.1 square feet
• Step 2: Calculate bags needed: 113.1 ÷ 100 = 1.13 bags, round up to 2 bags
• Step 3: Calculate cost: 2 bags × $5 = $10
• Result: Buy 2 bags of mulch, total cost $10

Example 3: L-Shaped Room

Scenario: An L-shaped room with two sections: Section A is 15ft × 12ft, Section B is 8ft × 10ft.

Calculation:

• Step 1: Calculate Section A: 15 × 12 = 180 square feet
• Step 2: Calculate Section B: 8 × 10 = 80 square feet
• Step 3: Add sections together: 180 + 80 = 260 square feet
• Result: Total room area is 260 square feet

Example 4: Land Parcel in Acres

Scenario: You're buying land that measures 350 feet × 450 feet and need to know the acreage.

Calculation:

• Step 1: Calculate area in square feet: 350 × 450 = 157,500 sq ft
• Step 2: Convert to acres: 157,500 ÷ 43,560 = 3.616 acres
• Result: The land parcel is approximately 3.6 acres

Common Area Calculation Mistakes

Mistake 1: Confusing Area with Perimeter

Problem: People confuse area (space inside) with perimeter (distance around).

Example: A 10ft × 12ft room has:

• Area: 120 square feet (10 × 12) — tells you how much flooring needed
• Perimeter: 44 feet (10 + 12 + 10 + 12) — tells you how much baseboard needed

Remember: Area uses square units (sq ft, sq m), perimeter uses linear units (ft, m).

Mistake 2: Using Diameter Instead of Radius

Problem: Circle area formula uses radius (center to edge), but people often measure diameter (edge to edge).

Wrong: Circle with 10-foot diameter → π × 10² = 314.16 sq ft (INCORRECT)

Correct: Circle with 10-foot diameter → radius is 5 feet → π × 5² = 78.54 sq ft

Solution: Always divide diameter by 2 to get radius before calculating.

Mistake 3: Mixing Units

Problem: Measuring length in feet but width in inches, then multiplying directly.

Wrong: Room is 10 feet long and 120 inches wide → 10 × 120 = 1,200 (nonsense units)

Correct: Convert inches to feet first: 120 inches ÷ 12 = 10 feet → 10 × 10 = 100 sq ft

Solution: Convert all measurements to the same unit before calculating.

Mistake 4: Forgetting to Divide by 2 for Triangles

Problem: Using base × height for triangle area (that's for rectangles!).

Wrong: Triangle with base 10 and height 8 → 10 × 8 = 80 sq ft (INCORRECT)

Correct: Triangle area = (base × height) ÷ 2 → (10 × 8) ÷ 2 = 40 sq ft

Remember: A triangle is half a rectangle, so always divide by 2.

Mistake 5: Not Adding Waste Allowance

Problem: Ordering exactly the calculated amount of material without extra for waste.

Result: Running out of flooring, tiles, or other materials mid-project.

Solution: Always add 10-15% extra (10% for simple layouts, 15% for complex patterns, 20% for diagonal tile layouts).

Material Estimation Based on Area

Once you know your area, use these guides to estimate materials needed:

Flooring Materials

Paint Coverage

• Standard Paint: 1 gallon covers 350-400 sq ft (one coat)
• Primer: 1 gallon covers 200-300 sq ft (absorbs into surface)
• Typical Room: Calculate wall area (perimeter × height), subtract doors/windows, divide by coverage rate
• Two Coats: Double your paint quantity for standard two-coat coverage
• Textured Walls: Reduce coverage rate by 20% (paint absorbs into texture)

Landscaping Materials

Troubleshooting Area Calculations

Issue: Results Seem Too Large or Too Small

Common Causes:

• Mixed units (measured in feet but entered as inches, or vice versa)
• Used diameter instead of radius for circles
• Confused area with perimeter
• Decimal point error (entered 10 instead of 1.0, or vice versa)

Solution: Double-check all measurements and units. Verify the result makes sense—a small bedroom shouldn't be 1,000 sq ft or 10 sq ft.

Issue: Ordered Materials Don't Fit

Common Causes:

• Forgot to add waste allowance (need 10-15% extra)
• Didn't account for irregular layouts or cuts
• Material comes in specific sizes that don't divide evenly

Solution: Always round up when ordering materials. Add appropriate waste percentage. Check product packaging for actual coverage (may differ from theoretical calculation).

Issue: Complex Room Shape Calculation

Problem: Room has angles, curves, or irregular features.

Solution: Break into simple shapes:

• Divide L-shaped rooms into two rectangles
• Separate bay windows or alcoves and calculate individually
• Approximate curves as rectangles or triangles
• Calculate total area, then subtract cutouts (doorways, built-ins)