Siding Calculator
Estimate siding units (squares, boxes, or panels) from wall dimensions with a built-in waste factor.
Your Siding Estimate
- Measure wall length and height — use total outside wall dimensions. Subtracting openings is optional if you use a normal waste factor.
- Pick a coverage type — choose squares (common estimating unit) or a box/bundle estimate for ordering.
- Set waste — use 8–12% for simple walls; increase for lots of corners, windows, and cuts.
- Round up — siding is sold in whole boxes/bundles, and color lots can vary between shipments.
How Much Siding Do I Need?
Siding is usually estimated from total wall area. Multiply wall length by wall height to get square feet, then add a waste factor for cuts, corners, and damaged pieces. Many suppliers quote siding in “squares,” where 1 square equals 100 square feet.
If you are estimating by boxes or bundles, use the coverage rate on the product label. Coverage varies by profile and exposure, so the calculator lets you choose a common estimate and apply a realistic waste percentage.
Quick Reference: Squares by Wall Area
Recommended Waste by Job Complexity
Waste depends more on wall complexity than on total area. Simple rectangular walls with few openings can stay near 8–10%. Many windows, corners, gables, and trim-heavy layouts often land in the 12–15% range. If you are matching an existing exterior, buying extra is safer than trying to source the same color lot later.
Waste Guidelines
Formulas Used in This Calculator
Siding quantity calculation:
1 = Adjusted area = base area × (1 + waste %)
2 = Units needed = adjusted area ÷ coverage rate (then rounded up)
3 = If using squares: coverage rate = 100 ft² per square
Related Calculators
Siding coverage depends on panel size and waste factor. Browse the surface calculator collection.
Frequently Asked Questions
What is a siding “square”?
A siding square is a standard estimating unit equal to 100 square feet of coverage. Many quotes and material takeoffs use squares because it stays consistent across different siding products.
Should I subtract windows and doors from wall area?
You can, but most estimates keep total wall area and use a realistic waste factor (12–15%). It often balances out cuts around openings, starter strips, and damaged pieces.
Why does the calculator round up?
Siding is sold in full boxes/bundles, and you typically can't buy partial packaging. Rounding up also protects you against breakage and color-lot differences.
What is the most durable siding material?
Fiber cement (like HardiePlank) is widely considered the most durable residential siding — it resists rot, insects, fire, and impact, and lasts 30–50 years. Vinyl is the most popular for low cost and zero-paint maintenance. Wood requires painting or staining every 5–10 years. Engineered wood offers a compromise between cost and durability.
How much does it cost to side a house?
Vinyl siding costs $3–$8 per square foot installed. Fiber cement runs $6–$13/ft² installed. A typical 1,500 ft² ranch home has roughly 12–15 squares of wall area, putting a full re-side at $4,000–$20,000 depending on material and local labor rates.