Metal Roofing Calculator
Calculate the number of metal roofing panels needed for your project. Enter your building dimensions, roof pitch, and panel size to get panel count, screw quantity, closure strips, and ridge cap length. Works for corrugated, standing seam, and ribbed metal panels.
Metal Roof Parameters
Save Roof Project
Metal Panel Output
Additional Materials
How to Calculate Metal Roofing Panels
Metal roofing is sold in panels of specific widths and lengths. To calculate how many panels you need:
- Calculate Roof Area: Multiply the building footprint by the pitch multiplier.Roof Area = Length × Width × √(1 + (Pitch÷12)²)
- Add Waste Factor: Multiply roof area by (1 + waste percentage).Total Area = Roof Area × (1 + Waste%)
- Calculate Panel Coverage: Multiply panel width (in feet) by panel length (in feet).Panel Coverage = (Width (in) ÷ 12) × (Length (in) ÷ 12)
- Divide and Round Up: Divide total area by panel coverage and round up to the next whole panel.Panels = ⌈Total Area ÷ Panel Coverage⌈
Example Metal Roof Calculation
Let's calculate panels for a 40x30 foot building with a 6:12 pitch, using 36-inch x 12-foot panels with 7% waste:
- Footprint: 40 ft × 30 ft = 1,200 sq ft
- Pitch Multiplier: √(1 + 0.5²) = 1.118
- Roof Area: 1,200 × 1.118 = 1,342 sq ft
- With 7% Waste: 1,342 × 1.07 = 1,436 sq ft
- Panel Coverage: 3 ft × 12 ft = 36 sq ft per panel
- Panels Needed: 1,436 ÷ 36 = 39.9 → 40 panels
- Screws: 1,342 × 1.5 = 2,013 screws
Common Mistakes in Metal Roof Estimation
- Using Nominal vs. Coverage Width: Metal panels have a nominal width (the physical sheet width) and a coverage width (the exposed width after overlapping). Always use the coverage width, which is typically 36 inches for corrugated panels even though the sheet is 38 inches wide.
- Not Ordering Extra Panels: Metal panels are custom-cut to length. If you damage a panel during installation, you cannot easily get a replacement. Order 2-3 extra panels as spares.
- Underestimating Screw Quantity: High-wind areas require more fasteners. In wind zones, use 2 screws per square foot instead of 1.5. Check your local building code for fastener spacing requirements.
Frequently Asked Questions
How many metal roof panels do I need?
Divide your total roof area (including waste) by the coverage area of one panel. A standard 36-inch wide, 12-foot long panel covers 36 square feet. For a 1,500 sq ft roof with 7% waste, you need 1,605 sq ft divided by 36, which equals approximately 45 panels.
How much waste should I add for metal roofing?
Metal roofing typically requires 5-10% waste factor. Simple gable roofs with few penetrations need 5%, while roofs with many valleys, dormers, or skylights need 10%. Always order a few extra panels for future repairs.
How many screws per square foot of metal roofing?
Standard corrugated metal roofing requires approximately 1.5 screws per square foot of roof area. This includes fasteners at every rib on the overlaps and every other rib in the field. A 1,000 sq ft roof needs approximately 1,500 screws.