DIY & materials
Roof tiles and slates Calculator
Convert horizontal roof area to pitched covering and ridge units. This free roof tiles and slates calculator shows the calculation and its assumptions so you can compare your own figures.
Your results
Convert horizontal roof area to pitched covering and ridge units.
Calculated outcomes
- Ridge Units
- 23
- Covering Cost
- €2,034.00
Assumptions and estimates
- Method: Pitched area = horizontal area ÷ cos(pitch). Covering uses manufacturer units/m²; ridge units use effective covered length.
- Uniform roof pitch estimate. Manufacturer headlaps and exposure determine coverage; roof fixings, ventilation and structural design are excluded.
Useful next steps
- Use Compare options to test an alternative side by side.
- Copy, print or download a record of this calculation when you need one.
Reports open your email app addressed to s@s1.ie with the public page address only. Your inputs are never added.
How the roof tiles and slates calculation works
Pitched area = horizontal area ÷ cos(pitch). Covering uses manufacturer units/m²; ridge units use effective covered length.
Uniform roof pitch estimate. Manufacturer headlaps and exposure determine coverage; roof fixings, ventilation and structural design are excluded.
Using this calculator
- Enter your own figures in the labelled inputs. Keep the currencies, units and time periods consistent.
- Choose any applicable rate profile, pattern or assumption shown for this tool. Open additional inputs when relevant.
- Review covering units and roof area m2, then read the stated assumptions and eligibility conditions before using the result.
Worked example
This is a static example using illustrative inputs, not facts about you or today’s date. The displayed eligibility selections and assumptions apply only to this example.
See example inputs
- Horizontal roof plan area (m²)
- 80
- Roof pitch (degrees)
- 30
- Manufacturer covering units per m²
- 10
- Waste allowance (%)
- 10
- Covering price per unit (€)
- 2
- Ridge length (m)
- 10
- Effective ridge unit length (m)
- 0.45
- Covering Units
- 1,017
- Roof Area M2
- 92.38 m²