Roof shingle calculator
Estimate roof squares, shingle bundles, and ridge caps from footprint, pitch, and waste.
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Tool guide
Roof shingle calculator: how it works
Practical information to understand the result and use this tool correctly.
About Roof shingle calculator
This roof shingle calculator turns a horizontal footprint and a pitch into sloped area, roofing squares, and whole bundles to buy. It is a purchase planner, not a structural or code review.
Plan area is length times width. The pitch factor is the square root of 1 plus (rise/run) squared, which converts horizontal area into sloped roof area. One square is 100 square feet (about 9.29 m²). Bundles are the sloped area with waste, divided by that square, times bundles per square, then rounded up.
Use it when a supplier sells asphalt shingles by the bundle and quotes coverage as three bundles per square for 3-tab, or three to five for architectural products. Optional ridge length uses a separate coverage per bundle so hip-and-ridge caps are not mixed into field shingles.
It assumes a simple rectangular footprint. Valleys, dormers, and cut-up roofs need the extra-area field or a higher waste percentage (often 15% instead of 10%). Slopes under 2/12 are usually not shingle roofs; the tool warns but does not block the math. Always confirm coverage on the bundle you will buy.
How to use it
- 1Choose meters or feet, then enter the horizontal roof length and width.
- 2Set rise and run (6/12 is a common gable) or pick a preset.
- 3Add waste, bundles per square, and optional ridge length and price.
- 4Read squares, field bundles, and ridge bundles. Copy the summary before you order.
Frequently asked questions
- How is a roofing square calculated?
- Sloped area in square feet divided by 100. In meters, area is converted with 1 m² = 10.7639 ft² before that division. Waste is applied before rounding bundles up.
- How many bundles are in a square?
- Most 3-tab asphalt shingles use 3 bundles per square. Architectural shingles are often 3, sometimes 4 or 5. The preset only fills the field; change it to match the label.
- Does the calculator run in the browser?
- Yes. Dimensions stay on your device. Nothing is uploaded and there is no account.
- What waste percentage should I use?
- About 10% for a simple gable and 15% for hips, valleys, or a steep cut-up roof. Waste does not replace measuring extra dormer area.
- Can I use this for metal or tile roofs?
- Only as an area and square estimate. Panel, clay, or concrete tile coverage is not the same as asphalt bundles. Set bundles per square to the product sheet or ignore bundle count and use the area.