Gutter Slope Calculator
Calculate the required gutter slope and drop for proper drainage.
Enter your gutter run length to find the ideal downward pitch.
Gutter Slope Needed
Gutter slope (also called pitch or grade) ensures water flows toward the downspout instead of pooling.
Standard gutter slope:
Drop = Gutter Run Length × Slope Rate
Recommended slope: 1/4 inch per 10 feet of gutter run (0.025 in/ft)
- Minimum slope: 1/16 inch per foot (may cause slow drainage)
- Standard slope: 1/4 inch per 10 feet (most common)
- Maximum recommended: 1/2 inch per 10 feet (for heavy rain areas)
Key rules:
- Maximum gutter run to a single downspout: 35–40 feet
- For runs over 40 feet, slope from the center to downspouts at each end
- The high point should be at the farthest end from the downspout
- Ensure fascia board is level before calculating slope
Example: A 30-foot gutter run needs a total drop of 3/4 inch (30 ÷ 10 × 0.25).