Metal roof panel calculator
Metal roofing is estimated by panel coverage width, not by the square — which is exactly where simpler calculators get it wrong.
How metal is measured
Panels are sold by the piece. What matters is the coverage width — the usable width after the seams overlap, which is always less than the panel's overall width. Standing seam is commonly 16", 5V crimp 24", and R-panel 36".
The formula
Panels per run = eave length ÷ (coverage width ÷ 12), rounded up. Multiply by the number of runs (planes), then add 10–15% for cuts and valleys. Panel length matches the slope length of each plane.
Why not bundles per square
A flat per-square figure hides the overlap. Two roofs with the same area need different panel counts if their eave lengths differ, because panels run eave-to-ridge in whole widths. The coverage-width model gets this right; a bundles-per-square shortcut does not.
Suitable pitches
Metal is the most flexible material for low slopes. Exposed-fastener panels need about 3:12; standing seam can go far lower — down to roughly 1/4:12 with the right mechanically-seamed system — making metal the common choice where shingles won't work.
Lifespan and cost
Metal roofs commonly outlast asphalt by decades, which is the main argument for the higher up-front cost. We don't publish dollar figures because they swing by region, gauge, and profile — enter your own price per square in the cost estimator.
Trade-offs
Light weight (good for re-roofing over questionable structure), excellent water shedding, and long life — against higher material cost, the need for trained installers, and oil-canning or noise concerns on some profiles.