How Much Siding Do I Need? Siding Calculator (2026)

Planning to re-side your house but unsure how much material to order? Siding is expensive, and accurate calculations prevent costly over-ordering or project delays from running short.

Quick Answer: Use a Siding Calculator

Our Siding Calculator calculates materials instantly:

Total square footage needed
Accounts for doors and windows
Includes 10% waste factor
Works for all siding types

Average house (139 m² living space): Approximately 167-204 m² of siding needed.

Step-by-Step: Calculate Siding Manually

Step 1: Measure Each Wall

For each exterior wall:

Measure width (ft)
Measure height from foundation to roof peak
Calculate area: Width × Height
Add all walls together

Example house:

Front: 12 m × 6 m = 74 m²
Back: 12 m × 6 m = 74 m²
Left side: 9 m × 5.5 m = 50 m²
Right side: 9 m × 5.5 m = 50 m²
Total: 249 m²

Step 2: Measure Gable Ends

For triangular gable areas: Formula: (Width × Height) ÷ 2

Example (two gables):

Each: (9 m × 2.4 m) ÷ 2 = 11 m²
Both: 22 m²

Step 3: Subtract Doors and Windows

Standard sizes:

Door: 1.9 m²
Window: 1.4 m²
Garage door: 9.3-13.9 m²

Example (3 doors, 12 windows, 2 garage doors):

Doors: 3 × 20 = 5.6 m²
Windows: 12 × 15 = 16.7 m²
Garage: 2 × 120 = 22.3 m²
Total deduction: 44.6 m²

Step 4: Calculate Net Area

Formula: Total area - Deductions

Example: 2,680 + 240 - 480 = 226.7 m²

Step 5: Add Waste Factor

Always add 10% for cutting waste, mistakes, and future repairs.

Example: 2,440 × 1.10 = 249.3 m² needed

Siding Coverage by Type

Vinyl siding:

Coverage: 9.3 m² per box (nominal)
Actual coverage: ~8.8 m² (waste built in)
Example: 249.3 m² ÷ 9.3 m²/box = 27 boxes

Fiber cement (HardiePlank):

Coverage: 2.3-2.8 m² per plank (8.25" wide × 12 ft)
Example: 249.3 m² ÷ 2.5 m²/plank = 100 planks

Wood siding (lap):

Coverage: Depends on width and overlap
6" exposure: 4.6 m² per bundle
Example: 249.3 m² ÷ 4.6 m²/bundle = 54 bundles

Don't Forget Trim and Accessories

Additional materials needed:

J-channel (around windows/doors): Measure perimeter
Corner posts: Measure total corner height
Starter strip: Measure house perimeter
Soffit and fascia: Measure eave length
Trim boards: Doors and windows

Siding Material Costs

Vinyl siding:

Material: $3-8 per m²
Installation: $3-6 per m²
Total installed: $6-14 per m²

Fiber cement:

Material: $5-12 per m²
Installation: $5-10 per m²
Total installed: $10-22 per m²

Wood siding (cedar):

Material: $6-15 per m²
Installation: $4-8 per m²
Total installed: $10-23 per m²

Engineered wood:

Material: $4-9 per m²
Installation: $3-6 per m²
Total installed: $7-15 per m²

Pro Tips for Siding Projects

1. Always round up
Buy the next full box/bundle. Can't buy half a box.

2. Buy from same lot
Color variations exist between production runs. Order all material at once.

3. Order 15% extra for complex designs
Houses with lots of corners, dormers, or angles create more waste.

4. Save extra pieces
Keep leftovers for future repairs. Matching faded siding is nearly impossible.

5. Check local codes
Some HOAs and municipalities restrict siding materials and colors.

Common Siding Calculation Mistakes

Mistake #1: Measuring living space, not exterior
Exterior walls are larger due to wall thickness. Measure outside dimensions.

Mistake #2: Forgetting gables
Triangular areas add significant square footage.

Mistake #3: Not accounting for waste
Cutting around windows and corners creates 5-10% waste minimum.

Mistake #4: Ignoring material type
Different sidings have different coverage rates per bundle/box.

House Size Siding Estimates

93 m² house:

Siding needed: 111-139 m²
Vinyl cost: $7,200-12,000 installed

139 m² house:

Siding needed: 167-204 m²
Vinyl cost: $10,800-17,600 installed

186 m² house:

Siding needed: 223-279 m²
Vinyl cost: $14,400-24,000 installed

232 m² house:

Siding needed: 279-348 m²
Vinyl cost: $18,000-30,000 installed

Frequently Asked Questions

How many squares of siding do I need?
One "square" = 9.3 m². Divide your total square footage by 100. A 186 m² house needs about 24-30 squares.

How much does it cost to side a 139 m² house?
Vinyl: $10,800-17,600. Fiber cement: $18,000-33,000. Includes materials and labor.

Can I put siding over old siding?
Sometimes, but not recommended. Adds weight, hides rot issues, voids warranties. Best practice is removal.

How long does siding last?
Vinyl: 20-40 years. Fiber cement: 30-50 years. Wood: 15-40 years with maintenance.

Do I need house wrap under siding?
Yes. House wrap (Tyvek) is critical for moisture protection and energy efficiency.

What's the best siding for my climate?
Hot/humid: Vinyl or fiber cement. Cold: Insulated vinyl or fiber cement. Coastal: Fiber cement (salt resistant).

Calculate Your Siding Needs

Get an accurate estimate for your specific house:

Use Our Free Siding Calculator

Instantly calculate:

Total square footage needed
Waste-adjusted quantities
Estimated material costs

No guesswork. Know exactly what to order before you buy.

Updated: February 2026

How Much Siding Do I Need? House Siding Calculator Guide