Calculadora de Telhado
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
área_real = base / cos(atan(inc/100)); telhas = ceil(área × rend × 1,1)
About this calculator
The Roof Calculator is a free online tool that helps you properly size the roof of your construction. Based on the width and length of the base, the slope percentage, and the tile yield per square meter, it calculates the actual roof area (considering the slope), the approximate number of tiles needed (with a 10% margin for waste and cuts), and the estimated total load on the structure. It is ideal for residential projects, renovations, and new constructions.
The calculation works as follows: first, the slope percentage is converted into an angle using the arctangent function. Then, the actual roof area is obtained by dividing the horizontal projection area (base) by the cosine of that angle. The number of tiles is calculated by multiplying the actual area by the yield per square meter and then adding a 10% margin. Finally, the total load is estimated by multiplying the actual area by an average weight per square meter (considering tiles and structure).
When to use this calculator? Whenever you are planning the roofing of a house, garage, porch, or any building with a sloped roof. It is useful for engineers, architects, masons, and homeowners who want a quick material estimate. It can also be used to check if the chosen slope is adequate for the tile type (e.g., ceramic tiles typically require a minimum slope of 30%).
Important precautions: the calculator provides an estimate; for definitive projects, consult a professional. The 10% margin may vary depending on roof complexity (cuts, ridges, valleys). The average weight considered is generic; special tiles (like concrete or fiber cement) have different weights. Always check the manufacturer's specifications and local technical standards (NBR 6123, NBR 15575).
Frequently asked questions
What is the minimum slope for ceramic tiles?
Typically, the minimum slope for ceramic tiles is 30% (about 17 degrees). Always check the manufacturer's recommendations.
How do I measure the roof slope?
The slope is the height (in cm) for every 100 cm of horizontal length. For example, a 30% slope means the roof rises 30 cm per meter.
Does the calculation account for cuts and ridges?
The calculator adds a 10% margin for waste, cuts, and ridges. For complex roofs, increase the margin to 15% or consult a professional.
Can I use different types of tiles?
Yes, but the yield (tiles/m²) and weight vary. The calculator allows you to input the yield; adjust the weight manually if needed.
Is the estimated load reliable for structural design?
It does not replace a full structural calculation. The load is an estimate for preliminary sizing. Consult an engineer for the final design.