You enter your roof length, pitch angle, and local rainfall rate. The tool applies NFPA drainage formulas to size gutters and determines downspout spacing. A steeper roof or heavier rain concentrates runoff, requiring bigger gutters (6" instead of 5"). Downspouts are spaced closer on high-rain roofs (20 ft apart) and farther on light-rain roofs (30 ft apart). The cost is computed from typical aluminum gutter pricing ($5–$10 per linear foot).
A 6" gutter holds about 26% more water volume than a 5" gutter. It's needed in heavy-rain or steep-roof areas to prevent overflow during storms. 5" is standard for most climates.
Pitch is the slope ratio (rise ÷ run). A 6:12 pitch means the roof rises 6 inches for every 12 inches of horizontal distance. You can estimate by looking at your roof angle, or measure it with a level and ruler. Your roof inspector or home survey may also list it.
You can, but closer spacing is safer and reduces overflow risk during heavy rain. If you use wider spacing, monitor the gutter after storms. Local building codes may also specify minimum downspout frequency.
The estimate covers gutter material and basic downspout costs. It does not include labor, hangers, fascia boards, or soil drainage systems. Get local quotes from contractors for a true project cost.
Gutter guards reduce leaf buildup and maintenance but add $3–$5 per linear foot. They're recommended in areas with heavy tree coverage or where you want minimal cleaning. Calculate the cost separately.
Estimate only. Results reflect your inputs and standard formulas. Double-check important decisions independently.