Filtro fluxo (L/min)
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
Area × mm/h × 0.8
About this calculator
This calculator estimates **rainwater flow rate** (in liters per minute) over a specific area, such as roofs or pavements. It uses the formula: Area (m²) × rainfall (mm/h) × 0.8, where 0.8 represents the typical collection efficiency of rainwater harvesting systems.
The result helps size **rainwater filters**, storage tanks, or gutters. For example, a 50 m² roof with 50 mm/h rainfall yields a theoretical 2000 L/min flow, but the 0.8 factor adjusts this to 1600 L/min for practical use.
Measure the **effective collection area** (e.g., roof slope) and the **average rainfall intensity** in your region. Factors like obstructions, roofing material, or slope may affect the theoretical estimate.
Use this tool for sustainable construction projects, water tank calculations, or urban drainage planning. Always check local technical standards to ensure structural safety.
Frequently asked questions
Does the 0.8 factor in the formula account for losses?
Yes, the 0.8 factor represents the average efficiency of rainwater collection, considering losses from evaporation, obstructions, and surface variations.
How to measure the area correctly?
Use the horizontal area of the collection surface (e.g., roof). Adjust for slope if present. Vertical surfaces are not counted.
Does rainfall intensity (mm/h) vary by region?
Yes, use local rainfall data. Typical values range from 10 to 100 mm/h depending on the climate.
Can this calculator be used for residential projects?
Yes, it's ideal for sizing storage or filtration systems for homes or small buildings. Consult local technical standards for validation.
Why doesn’t the formula include seconds in the time unit?
The mm/h unit already incorporates time variation. The formula automatically converts to liters per minute by multiplying area and efficiency.