Roofing fastener estimate
Metal Roof Screw Calculator
Estimate how many screws you need for exposed-fastener metal roofing panels. Enter the roof width, panel length, coverage width, fastening row spacing, and screw pattern to plan boxes and material cost before ordering.
How to use the metal roof screw calculator
- Measure the roof width along the eave and the panel length up the roof slope.
- Enter how many matching roof planes use that same layout.
- Set the panel coverage width, fastening row spacing, and screws per row from the panel instructions.
- Add a waste allowance, box size, box price, and any extra trim or ridge screws.
The calculator estimates panel count, fastener rows, field screws, extra screws, total screws with allowance, boxes to buy, and approximate fastener cost.
Metal roofing screw estimate example
For a simple 40 ft wide gable roof with two 16 ft slopes, 36 inch panel coverage, 24 inch fastener row spacing, and 4 screws per row, the roof uses about 28 panels. With lap screws, trim screws, and a 12% allowance, the estimate is roughly 1,300 screws, or six 250-count boxes.
Your actual screw count may be higher at edges, corners, high-wind zones, roof penetrations, ridge caps, and trim pieces. Manufacturer patterns beat any generic rule of thumb.
Metal roof screw FAQ
How many screws per square foot for metal roofing?
A rough planning range is about 0.8 to 1 screw per square foot for many exposed-fastener roofs. Layout-based estimating is better because it accounts for panel width, row spacing, edges, and trim.
How many screws are in a square of metal roofing?
One roofing square is 100 square feet. Many exposed-fastener estimates land around 80 to 100 screws per square, but the correct count depends on the fastening pattern for your specific panel.
Do I screw metal roofing on the rib or flat?
Follow the manufacturer's installation guide for your panel profile. Many exposed-fastener roof panels are fastened in the flat beside ribs, while some details and panel types differ.
What size screws are used for metal roofing?
Common residential and agricultural metal roofing often uses gasketed roofing screws such as #9, #10, #12, or #14 in lengths matched to the panel and substrate. The panel supplier should specify the right fastener.
Should I buy extra metal roofing screws?
Yes. A small buffer helps cover trim, ridge cap, dropped screws, damaged washers, and small layout changes. This calculator includes a percentage allowance plus an extra screw field.