Gutter Size Calculator
Calculate the correct gutter width, downspout diameter, and number of downspouts for your roof drainage system.
How to Use the Gutter Size Calculator
- Enter the roof catchment area in m².
- Enter the design rainfall intensity in mm/h.
- Enter the gutter slope in percent.
- Click Calculate to see gutter width, downspout diameter, and count.
Casos de Uso
- •Designing roof drainage systems for new buildings.
- •Upgrading undersized gutters on existing structures.
- •Stormwater management planning.
- •Compliance with drainage design standards.
Fórmula
Flow (L/s) = Roof area × Rainfall intensity / 3600. Gutter size and downspout count are derived from flow rate and slope.
Preguntas Frecuentes
What rainfall intensity should I use?
Use the 1-in-10 year storm intensity for your location. A common design value is 75 mm/h.
How many downspouts do I need?
One downspout per 50 m² of roof area is a common guideline, but the calculator adjusts this for your specific area.
Is it free?
Yes, all calculators on OhMyCalc are completely free.