Gutter Capacity Calculator — Calculate How Much Water Your Gutters Can Handle

Gutter Capacity Calculator

Calculate your gutter system’s water handling capacity. Determine if your gutters are sized properly for heavy rainfall in your area.

Step 1: Roof & Gutter Details

Understanding Gutter Capacity

Gutter capacity depends on roof area, gutter size, and local rainfall intensity. Larger roofs and heavier rainfall require larger gutters to prevent overflow and water damage.

Step 2: Rainfall & Location

About Rainfall Intensity

Rainfall intensity measures how much rain falls in a specific time period. Higher intensities (heavy downpours) require greater gutter capacity to handle the increased water flow from your roof.

Gutter Capacity Results

Summary
Gutter Comparison
Capacity Breakdown

Maximum Water Handling Capacity

125.50
Gallons per Minute
Required Capacity
125.50 GPM
Your Gutter Capacity
150.00 GPM
Safety Margin
19.5%
Performance Rating
Good

Gutter Size Comparison

Gutter Size Material Max Capacity Required Capacity Performance

Capacity vs Rainfall Intensity

Gutter Capacity Calculation Formula

Required Capacity = (Roof Area × Rainfall Intensity × 0.0104) × Roof Slope Factor

The required gutter capacity is calculated by multiplying roof area by rainfall intensity and applying appropriate conversion factors. Roof slope affects water velocity and must be considered for accurate sizing.

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