Roof measurement and metal roof calculator.
Enter the footprint, overhang and pitch to get the sloped area, squares, shingle bundles, metal panel count and panel length, plus eave, rake, ridge and hip lengths for trim.
Send one plan set. See what the AI extracts and what it flags for review. No obligation.
- Gable or hip
- Shingles or metal panels
- Pitch factor shown
1 · Footprint
2 · Pitch & waste
3 · Metal panels & price
Live formula
Save your results
Copy these results, then add your approved sample files in the trial brief.
Estimates only. Check every default against your spec, supplier data and crew records before you bid.
Standard formulas, shown on the page.
Nothing hidden. These are the same steps an estimator runs on a takeoff sheet.
1. Pitch factor
The slope multiplier converts plan (horizontal) area to actual roof area. For a 6/12 roof it is √(1 + 0.25) = 1.118.
2. Sloped area and squares
Add the overhang to both dimensions, multiply for plan area, then apply the pitch factor. One roofing square is 100 sq ft.
3. Metal panels
For a gable roof, each slope needs the eave length divided by the panel's net coverage, rounded up. Panel length is the rafter length: half the width (with overhang) times the pitch factor.
4. Edges for trim
Gable: eaves on two sides, four rake edges, ridge along the length. Hip: eaves all round, ridge = length − width, and four hips of run × √(2 + (rise ÷ 12)²).
Every default is cited or editable.
Replace any of these with your spec, supplier data sheet or job-cost history. The calculator recalculates instantly.
| Input | Default | Source |
|---|---|---|
| Waste | 10% | Editable assumption; hips, valleys and dormers typically need more |
| Bundles per square | 3 | Editable assumption for common 3-bundle shingles; check the wrapper |
| Panel coverage | 36 in | Editable assumption; use the net coverage on your panel data sheet |
| Roof geometry | Single ridge, uniform pitch | Simplified model; split complex roofs into planes |
Common pitches at a glance.
| Pitch | Factor | Angle |
|---|---|---|
| 3/12 | 1.0308 | 14.0° |
| 4/12 | 1.0541 | 18.4° |
| 5/12 | 1.0833 | 22.6° |
| 6/12 | 1.1180 | 26.6° |
| 8/12 | 1.2019 | 33.7° |
| 10/12 | 1.3017 | 39.8° |
| 12/12 | 1.4142 | 45.0° |
Factor = √(1 + (rise ÷ 12)²); angle = arctan(rise ÷ 12).
From calculator to bid: get the quantities off the drawings.
Speed is easy to promise. Defensible numbers are the job, so RenderDraw keeps the estimator in control of every quantity that gets priced.
- Source on every row. Each quantity keeps its source sheet, location and reviewer decision.
- Lowest confidence first. The review queue shows the drawing tile with the detection highlighted and the extracted value.
- Uncertain items flagged, not hidden. Anything the AI can't confirm goes to the estimator rather than being guessed.
- Nothing priced before approval. Rows move on to pricing only after they are accepted.
Questions estimators ask
How do you measure a roof in squares?
Measure the plan area including overhangs, multiply by the pitch factor to get the sloped area, then divide by 100. A 2,000 sq ft sloped roof is 20 squares before waste.
How do I calculate metal roof panels?
Divide the eave length of each slope by the panel's net coverage width and round up. Panel length equals the rafter length, which is the horizontal run times the pitch factor, plus any overhang.
What waste factor should I use for roofing?
Simple gables are often carried around 10%; hips, valleys and cut-up roofs need more. The default is an editable assumption.
Is this as accurate as a roof measurement report?
For a simple roof it gives the same geometry. Complex roofs with multiple planes, dormers and valleys should be broken into planes, or measured from drawings or aerial reports.
Can RenderDraw take off a commercial roof from drawings?
Yes. RenderDraw proposes roof areas by system, edge lengths and penetrations from the roof plan and details, for an estimator to review.
See what the AI reads on your own drawings.
Send one representative roofing plan set. RenderDraw reviews it and follows up with what the AI extracted and what it flagged for review. Your files remain private while the request is assessed, and there is no obligation.
- Upload roof plans, tapered insulation plans, roof details, the mechanical roof plan and the Division 07 spec sections.
- RenderDraw reviews the set and the scope you want tested.
- We follow up with extracted quantities, flagged items and next steps.