# Roofing Shingle Calculator

Roof area to squares, bundles and ridge cap.

- Page: https://jianzhujisuan.com/en/roofing-squares
- Category: Finishes (https://jianzhujisuan.com/en/c/finishes)
- Chinese version: https://jianzhujisuan.com/zh/roofing-squares.md
- Data checked: 2026-10-25

## Quick result

With the default inputs (Roof area 1500 ft², Shingle type Architectural (3 bundles/square), Ridge and hip length 60 ft, Waste Simple roof (+10%)): **Roofing squares 16.5 sq**

## Inputs

| Parameter | Type | Default | Unit | Note |
|---|---|---|---|---|
| Roof area | number | 1500 | ft² |  |
| Shingle type | select | Architectural (3 bundles/square) | — |  |
| Ridge and hip length | number | 60 | ft |  |
| Waste | select | Simple roof (+10%) | — |  |

## Formula

- **1 square = 100 ft²**: the roofing unit
- **Squares = area × (1+waste) ÷ 100**: 
- **Bundles = squares × 3**: same for 3-tab and architectural
- **Ridge cap = ridge length ÷ 35**: about 35 ft per bundle

## Worked example

1500 ft² gable roof in architectural shingles with 60 ft of ridge and 10% waste: 1650 ft² = 16.5 squares, 50 bundles of shingle and 2 bundles of ridge cap (60/35 = 1.7, rounded up). Total weight about 3630 lb, close to 1.8 tons.

## Questions

### How do I work out roof area?

Not from the footprint. For a gable, multiply projected area by the slope factor: 1.054 at 4/12, 1.118 at 6/12, 1.202 at 8/12 and 1.414 at 12/12. Hip roofs need another 5-10% for the extra hips. The reliable route is to measure the length and the raking length of one slope and multiply.

### Why 10-20% waste?

Shingles come in fixed widths, so eaves, rakes and hips all need cuts that leave half or most of a shingle unusable. A simple gable only cuts two rakes, so 10% does it; a hip roof cuts along every hip, so take 15%; skylights, dormers and chimneys push it to 20%. Better two extra bundles than a top-up from a different production run with a visible colour difference.

### Do I have to strip the old shingles?

Up to two layers can go over the old roof in many jurisdictions, provided the existing surface is flat and sound. It saves tear-off and dumpster costs, but doubles the weight, shows imperfections and guarantees a full strip next time. It also voids the manufacturer warranty - a 25 or 30 year warranty requires stripping back to the deck.

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Generated by BuildCalc. All calculations run in your browser; no data is uploaded. Formulas follow national standards and common trade practice; local codes govern.