Siding Calculator
Find the square footage and total cost of siding for a wall or gable — wood, metal, vinyl, brick, or anything else sold by the square foot or square meter. Enter your dimensions, subtract doors and windows, add a waste factor, and get an instant material and cost estimate.
Works for houses, garages, and outbuildings, whatever material you're planning to use.
- Wall or gable calculation
- Doors & windows subtracted
- Waste factor & total cost
- Free, no signup
Siding Calculator
How to Measure for Siding
What to measure, and how the area and cost are calculated.
Start with square footage
Since siding covers the walls or gables of a house, the whole calculation comes down to finding the square footage of the surface you're covering, then subtracting any openings — you don't want to cover your doors and windows with siding panels. All you need is a measuring tape or rangefinder to measure:
- The height and width of your wall or gable.
- The height and width of any doors and windows — this calculator assumes standard opening sizes by default, but you can adjust them if yours are unconventional.
- The number of each type of opening.
How much siding do I need?
Once the measurements are in, the total area of siding needed follows this formula:
Atot = (B × H − (n₁ × A₁) − (n₂ × A₂)) × (1 + w)
where B is the wall's width, H is its height, n₁ and A₁ are the number and area of doors, n₂ and A₂ are the number and area of windows, and w is the waste factor. If you're calculating for a gable rather than a straight wall, divide B × H by two first, to account for the triangular shape of a roof gable.
Understanding the waste factor
The waste factor accounts for material lost to trimming and cutoffs, expressed as a percentage of the net wall area. A typical value falls between 5% and 10% — the more complex the project (more corners, angles, and openings to cut around), the more waste you're likely to generate.
How much does siding cost?
To estimate cost, you need the unit price of your siding material — expressed as a price per unit area, such as $/ft² or €/m². Siding is often sold in "squares," a unit of area equal to 100 square feet; a typical box of vinyl siding might contain two squares, or 200 square feet. Always check how much material comes in a package and calculate the unit price rather than comparing box prices directly. Once you know the unit price, the total cost is simply:
Price = Unit Price × Total Area
How to Use This Calculator
Four groups of inputs, and a complete siding estimate.
Choose Wall or Gable
Select which surface you're covering — the calculation adjusts automatically for a gable's triangular shape.
Enter Dimensions
Input the height and width of your surface, plus your doors and windows if they're non-standard sizes.
Set Waste Factor & Price
Choose a waste percentage and enter your material's price per unit area.
Get Area & Cost
See the exact siding area needed and the total material cost together.
Siding Formulas
The core area and cost equations.
Wall Area
The straightforward area of a rectangular wall.
Gable Area
Dividing by two accounts for the triangular shape of a gable, compared to a full rectangle of the same base and height.
Openings Area
The combined area of all doors and windows, subtracted from the gross area before applying waste.
Total Price
Multiply the total siding area — already including waste — by your material's price per unit area.
Worked Example
Estimating siding cost for a wall with one door and two windows.
A Simple Rectangular Wall
A wall measures H = 8 m, B = 14 m, with one door (assume 1.8 m² per door) and two windows (assume 1.44 m² each), a waste factor of 5%, and a unit price of 18 €/m².
Note: this doesn't include labor, equipment, or extras like connectors and fasteners — be sure to add those separately when budgeting a real project.
Types of Siding
The four most common materials, and how they compare.
Vinyl siding
By far the most popular type of siding — durable, cheap, and available in a wide range of colors. It can last 30-40 years and is relatively easy to clean, with insulated options available. Its main drawback: it isn't waterproof, so poor installation can let water seep behind the panels and damage the walls beneath.
Metal siding
Looks stylish and resists water, weather, and fire. It's considerably heavier than vinyl, which drives up installation costs, and it's more prone to mechanical damage like scratching or denting on impact.
Wood siding
A natural, eco-friendly option with excellent insulating properties, and individual damaged boards can be replaced easily. However, it's less resistant to water and insect damage, and maintenance costs run high — expect to repaint every 4-5 years.
Brick siding
The most durable option by far, capable of withstanding over 100 years of harsh weather. It's fireproof and resistant to both water and insects. The tradeoff is cost and the high effort required for installation.
| Material | Lifespan | Main Drawback |
|---|---|---|
| Vinyl | 30–40 years | Not waterproof if poorly installed |
| Metal | 40+ years | Heavy, prone to dents/scratches |
| Wood | Varies, needs repainting every 4–5 yrs | Vulnerable to water & insects |
| Brick | 100+ years | High cost & installation effort |
Quick Reference Tables
Waste factor guidance and siding unit conventions.
| Project Complexity | Typical Waste Factor |
|---|---|
| Simple rectangular wall | 5% |
| Multiple corners, angles, or openings | 10% or more |
| Unit | Definition |
|---|---|
| 1 Square | 100 sq ft of siding material |
| Typical vinyl box | 2 squares = 200 sq ft |
Benefits of Using This Siding Calculator
Why it beats manual measuring and multiplication.
Wall or Gable
Handles both flat walls and triangular gables with the correct area adjustment.
Accurate Net Area
Automatically subtracts doors and windows from the gross area.
Adjustable Waste Factor
Account for trimming and cutoff losses with a customizable percentage.
Instant Cost Estimate
Enter a unit price and get the total material cost immediately.
Material Guidance
Compare vinyl, metal, wood, and brick before committing to a material.
Mobile-Friendly
Works well at the hardware store on a phone or at a desk while planning.
Where This Siding Calculator Helps
Real projects that need an accurate area and cost estimate.
New Home Construction
Estimating full exterior siding needs before ordering material.
Home Renovation
Replacing aging siding with a new material and style.
Gable End Siding
Calculating material for the triangular gable ends of a roofline.
Garage & Shed Exteriors
Costing out smaller structures to match a home's main siding.
Contractor Quoting
Pricing a siding job accurately across multiple walls for a client estimate.
Storm Damage Repair
Estimating replacement material after wind or hail damage.
Real Estate Renovation
Budgeting exterior updates before listing or flipping a property.
Insurance Estimates
Costing siding replacement for insurance claims.
Painting Projects
The same area-minus-openings method applies to estimating paint coverage too.
Material Comparison
Comparing total project cost across vinyl, wood, metal, or brick.
DIY Weekend Projects
Planning a manageable single-wall siding replacement.
Property Management
Budgeting exterior maintenance across multiple rental units.
Common Siding Estimating Mistakes
Avoid these errors before ordering material.
Forgetting to subtract doors and windows
Using the full gross area overstates the material and cost needed.
Forgetting to halve the area for a gable
A gable is triangular, not rectangular — using the full B × H figure without dividing by two doubles the true area.
Comparing box price instead of unit price
Siding boxes contain different quantities of material — always calculate the price per square foot or square meter before comparing options.
Skipping the waste factor
Cutting around corners and openings always wastes some material — leaving no buffer risks running short mid-project.
Forgetting labor and accessory costs
This calculator estimates material cost only — labor, fasteners, and trim pieces need to be budgeted separately.
Choosing a material without checking its drawbacks
Each siding type has real tradeoffs — vinyl's water sensitivity, wood's maintenance needs, metal's weight, and brick's cost are all worth weighing before choosing.
Frequently Asked Questions
Direct answers to the questions people ask most about siding estimating.
How much siding do I need?
Calculate the gross area of your wall or gable, subtract the combined area of doors and windows, then add a waste factor of about 5–10% to cover trimming and cutoffs.
How do I calculate siding cost?
Multiply the total siding area (including waste) by the material's price per unit area — for example, price = unit price × total area.
What is a "square" in siding measurements?
A square is a unit of area used in the siding industry, equal to 100 square feet. A box of vinyl siding often contains two squares, or 200 square feet.
How do I calculate siding for a gable?
Multiply the gable's base by its height, then divide by two to account for its triangular shape, before subtracting any openings and adding waste.
What is a typical waste factor for siding?
Usually 5–10%. Simple rectangular walls need less waste allowance; more complex projects with many corners and openings need more.
What is the most popular type of siding?
Vinyl siding is the most popular, thanks to its low cost, durability, and wide range of color options.
Which siding material lasts the longest?
Brick siding is the most durable, capable of withstanding over 100 years of exposure to harsh weather.
Is vinyl siding waterproof?
Not entirely — if installed poorly, water can seep behind the panels and damage the walls underneath, even though the panels themselves resist water well.
How often does wood siding need repainting?
Typically every 4-5 years, to protect it from water and insect damage and keep it looking its best.
Does this calculator account for labor costs?
No, it estimates material cost only — labor, equipment, and accessories like connectors should be budgeted separately.
Can I use this calculator for painting instead of siding?
Yes, the same gross-area-minus-openings approach works for estimating paint coverage as well.
Does this calculator use default door and window sizes?
Yes, standard sizes are pre-filled, but you can edit the height and width fields if your openings are a different size.
What's the difference between metal and vinyl siding?
Metal siding resists water, weather, and fire better and looks more stylish, but it's heavier (raising installation cost) and more prone to dents and scratches than vinyl.
Is this siding calculator free?
Yes, it's free to use with no signup required.
Can I use this calculator on mobile devices?
Yes, the layout is fully responsive and works on phones, tablets, and desktops.
Ready to Estimate Your Siding Project?
Get an accurate area and total cost for your wall or gable siding project in seconds.