# Siding Calculator: Squares & Panels Needed

> Estimate how many squares (100 sq ft) and how many pieces of siding you need for a house or shed, minus openings and plus waste.

**Quick answer:** Siding is sold by the square, which is 100 sq ft of wall. A one-story house with a 160 ft perimeter, 9-ft walls, 200 sq ft of gables and 12 openings needs about 16 squares with 10% waste. Formula: (perimeter × height + gables − openings) × 1.10 ÷ 100.

_Last updated: October 3, 2026. Estimates only; confirm quantities with your supplier._

## How to calculate siding

Siding is sold by the **square** — 100 square feet of wall coverage. To estimate it, find the gross wall area, subtract doors and windows, and add waste for cuts.

```
gross area = perimeter × wall height + gable areas
net area = gross − doors (21 sq ft) − windows (15 sq ft) − garage doors
squares = net area × (1 + waste %) ÷ 100
```

A gable end is a triangle: ½ × base × height. Add both ends. For multi-story houses, multiply perimeter by the total wall height, or calculate each story separately.

### Siding squares by house size (one story, 9 ft walls, typical openings)

| House footprint | Perimeter | Net wall area | Squares (+10%) |
| --- | --- | --- | --- |
| 24 × 32 ft | 112 ft | 984 sq ft | 10.8 |
| 28 × 40 ft | 136 ft | 1228 sq ft | 13.5 |
| 30 × 50 ft | 160 ft | 1458 sq ft | 16.0 |
| 40 × 60 ft | 200 ft | 1888 sq ft | 20.8 |

The chart assumes a gable end roughly 7 ft tall at the peak; use your own gable area for accuracy.

### Typical waste

Ten percent is normal for simple houses and 15% for houses with many corners, dormers or diagonal runs. Siding is manufactured in lots, so order everything together to avoid color differences.

### Accessories

Siding projects also need trim around windows and doors, outside and inside corner posts, J-channel, starter strips, fasteners, flashing and housewrap. Count these by linear feet of edge. Before re-siding, check the walls for moisture and add insulation if you're opening them up — see the [insulation calculator](../insulation-calculator/). For the roof above, use the [roofing calculator](../roofing-calculator/).

## Frequently asked questions

### What is a square of siding?

A square is 100 square feet of wall coverage.

### How do I measure a gable for siding?

Multiply the base of the gable by its height and divide by two. Add both gable ends.

### How much siding waste should I allow?

Add about 10% for typical homes and up to 15% for complex rooflines or diagonal patterns.

### How many pieces of vinyl siding are in a square?

A 12-foot double-4-inch panel covers about 8 square feet of wall, so roughly 12–13 panels per square. Check the box label.

### How much siding do I need for a 2,000 sq ft house?

A two-story 2,000 sq ft house usually has about 2,000–2,400 sq ft of wall area before openings — roughly 20–25 squares with waste.

### Vinyl, fiber cement or wood?

Vinyl is the cheapest and lowest maintenance; fiber cement is durable and fire-resistant but heavy and costlier; wood looks best but needs regular painting or staining.

### Do I need housewrap under siding?

Yes. A weather-resistant barrier under siding sheds water that gets behind it and is required by most codes.

### How do I price siding per square?

Installed siding is quoted per square. Multiply the squares from this calculator by the quoted price per square, then compare with material-only prices.

## Sources and further reading

- [Vinyl Siding Institute](https://www.vinylsiding.org/) — VSI: vinyl siding installation resources