# Siding Calculator

Calculate how much siding you need for your home. Supports vinyl, fiber cement, and wood siding. Subtracts doors and windows automatically.

## What this calculates

Replacing or installing siding is one of the biggest exterior home improvements. This calculator estimates the amount of siding material needed by computing wall area, subtracting doors and windows, and adding gable areas. Results are given in squares (1 square = 100 ft²) with a waste factor.

## Inputs

- **Total Wall Length** (ft) — min 0 — Add all wall lengths together
- **Wall Height** (ft) — min 1, max 30 — Measure from foundation to soffit
- **Gable Area (total)** (ft²) — min 0 — Total triangular gable area on all sides
- **Doors to Subtract** — min 0, max 10 — Standard door = ~21 ft²
- **Windows to Subtract** — min 0, max 40 — Standard window = ~15 ft²
- **Siding Type** — options: Vinyl (2 sq per box), Fiber Cement / Hardie Board, Wood Lap Siding
- **Waste Factor** (%) — min 0, max 20 — 10% for straight walls, 15% for complex facades
- **Price Per Square** ($) — min 0 — 1 square = 100 ft²

## Outputs

- **Gross Wall Area** (ft²)
- **Openings Area** (ft²)
- **Net Siding Area** (ft²)
- **Siding Squares** — 1 square = 100 ft²
- **Squares to Order** — Including waste factor
- **Estimated Material Cost** — formatted as currency

## Frequently Asked Questions

**Q: What is a square of siding?**

A: A square is a unit of measurement equal to 100 square feet of coverage. Siding is sold and priced by the square, similar to roofing. A box of vinyl siding typically covers 2 squares (200 ft²).

**Q: How do I calculate siding for gables?**

A: Measure the gable as a triangle: base width multiplied by peak height, divided by 2. For example, a 24-foot wide gable that is 6 feet tall at the peak has 72 square feet of area. Add gable area to the wall area in this calculator.

**Q: Which siding type is best?**

A: Vinyl siding is the most affordable ($3-12/ft² installed) and low-maintenance. Fiber cement (Hardie Board) is more durable and fire-resistant ($6-15/ft²). Wood siding offers a classic look ($6-12/ft²) but requires regular maintenance and painting.

**Q: Should I subtract all windows and doors from the siding area?**

A: Yes, subtract doors and windows to get accurate material estimates. However, you will still need trim pieces around each opening. Some installers leave openings in the estimate to ensure enough material for starter strips, J-channel, and trim.

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Source: https://vastcalc.com/calculators/construction/siding
Category: Construction
Last updated: 2026-04-21