Gutter Calculator
Calculate gutter length and downspouts needed from roof perimeter.
Assumptions used in this calculation
- Even downspout distribution: Spaces downspouts evenly along the perimeter, it doesn't account for specific low points, valleys, or corners where a downspout is structurally required regardless of spacing.
- No extra length for seams or end caps: Gutter length is taken as exactly the roof perimeter, with no added allowance for overlaps, end caps, or corner miter pieces.
About this calculator
The gutter calculator takes a roof's perimeter and standard downspout spacing to estimate the total gutter length and number of downspouts needed for proper drainage.
Worked example
120ft roof perimeter, 35ft downspout spacing
Result: 120ft of gutter, 4 downspouts
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