How to Use This Calculator
- Select your roof type — gable, hip, or single-slope/shed.
- Enter your house length and width in feet.
- Choose gutter size (5-inch or 6-inch) and number of stories.
- Get your results — total gutter length, downspout count, and a full parts list with brackets, elbows, and end caps.
Gutter Length by Roof Type
| Roof Type | Gutter Placement | Example (50 x 30 ft) |
|---|---|---|
| Gable | Two long sides (eaves) | 100 ft of gutter |
| Hip | All four sides | 160 ft of gutter |
| Single Slope / Shed | One low side | 50 ft of gutter |
5-Inch vs 6-Inch Gutters
Standard 5-inch K-style gutters handle most residential roofs. They can drain about 5,520 square feet of roof area in moderate rainfall (1 inch per hour). If your roof area exceeds this or you live in a heavy-rain region, upgrade to 6-inch gutters which handle 7,960 square feet.
| Gutter Size | Max Roof Area | Cost per Foot | Best For |
|---|---|---|---|
| 5-inch K-style | 5,520 sq ft | $3 - $5 | Most homes |
| 6-inch K-style | 7,960 sq ft | $4 - $8 | Large roofs, heavy rain areas |
| 5-inch half-round | 4,000 sq ft | $5 - $9 | Historic / aesthetic preference |
Downspout Placement Rules
- One downspout per 40 feet of gutter, minimum. A 50-foot gutter run needs 2 downspouts.
- Place at corners where water naturally flows. Avoid placing near doors or high-traffic walkways.
- Use 3 elbows per downspout — two at the top (outlet to wall) and one at the bottom (away from foundation).
- Extend 4-6 feet from foundation using splash blocks or underground drain pipes.
DIY vs Professional Installation
Sectional aluminum gutters (10-foot sections) are DIY-friendly for single-story homes. Budget $3-5 per linear foot for materials. Professional seamless gutter installation runs $6-12 per foot but produces no seam leaks and is the better choice for two-story homes.
FAQ
How often should gutters be cleaned?
At minimum twice a year — spring and fall. If you have overhanging trees, clean quarterly. Clogged gutters cause water to overflow and damage fascia boards, siding, and foundations.
Do I need gutter guards?
Gutter guards reduce cleaning frequency but do not eliminate it. Micro-mesh guards ($6-12 per foot installed) are the most effective. They keep out leaves, pine needles, and shingle grit while allowing water through.
What slope should gutters have?
Gutters should slope 1/4 inch per 10 feet toward the nearest downspout. For a 40-foot run, that means 1 inch of drop from end to end. Too little slope causes standing water; too much looks visibly crooked.
⚠ Disclaimer
Gutter sizing and downspout placement are estimates based on general guidelines. Actual requirements depend on local rainfall intensity, roof pitch, and drainage conditions. For multi-story homes or complex rooflines, consider professional installation. Improper gutter drainage can cause foundation damage — ensure downspouts direct water at least 4-6 feet from the foundation.