Free tool: Division 07 roofing
Roofing estimator: squares, materials and your roofing estimate
Turn plan area and pitch into roof squares, then bundles or membrane rolls, edge and ridge lengths. Add your own prices for a roofing estimate per square and per square foot.
Fixed price in 2 business hours. Pay only after you accept.
- Fixed price agreed before any work starts
- Plan review is free
- You pay only after you accept the price and delivery date
- Single-trade estimates in 48 hours
Quick answer
The Bidmere roofing estimator converts the roof’s plan area and pitch into roof squares, adds waste, and counts shingle bundles or membrane rolls plus drip edge and ridge cap. Enter your material, labor and tear-off rates to get a total, a cost per square and a roofing cost per square foot. It is free.
Division 07: Roofing
Roofing estimate calculator
Roof squares from plan area and pitch, bundles or membrane rolls, edge and ridge lengths, and cost per square at your own prices.
Results
Bidding a commercial job? Send the plans and get a measured takeoff
Get a fixed quote Fixed price in 2 business hours. Plan review is free. Pay only after you accept.Need the whole job measured? This calculator covers one area at a time. Send the plans and we return the full takeoff and estimate. Fixed quote within 2 business hours. Plan review is free, and you pay only after you accept.
Get a fixed quoteHow to use the roofing estimator
Measure the roof footprint, set the pitch, pick the system, then add your costs. Results update as you type.
- Plan area. Length and width of the horizontal footprint from the roof plan, overhangs included. Add separate roof areas at the same pitch on the extra line.
- Pitch. Rise in inches per 12 in of run. Use 0.25 for a 1/4 in 12 low slope roof. For mixed pitches, enter your own multiplier.
- Roof system. Steep slope shingles, low slope membrane rolls, or squares only for metal, tile and other systems.
- Waste. Simple gables need less; hips, valleys and dormers need more.
- Edges and ridges. Eaves, rakes, hips and ridges, and valleys in lineal feet, for drip edge, starter and cap counts.
- Your unit costs. Material per square, install labor per square, tear-off per square and a lump sum for flashing, edge metal or a dumpster.
Run each roof area separately when pitch or system changes.
How the roofing estimate is calculated
Roof squares equal plan area times the pitch multiplier, divided by 100. One roofing square is 100 square feet of roof surface.
| Step | Formula |
|---|---|
| Plan area | Length (ft) x width (ft) + extra plan area |
| Pitch multiplier | Square root of (1 + (rise / 12) squared) |
| Roof surface area | Plan area x pitch multiplier |
| Squares | Roof surface area / 100 |
| Squares with waste | Squares x (1 + waste %) |
| Shingle bundles | Squares with waste x bundles per square, rounded up |
| Membrane rolls | Roof area x (1 + waste %) / net coverage per roll, rounded up |
| Cost per square | Total cost / net squares |
| Cost per SF | Total cost / roof surface area |
Common multipliers from the formula: 4 in 12 is 1.054, 6 in 12 is 1.118, 8 in 12 is 1.202, 12 in 12 is 1.414. A 1/4 in 12 low slope roof is 1.0002, so plan area and roof area are almost the same. The multiplier covers a roof that slopes in one direction from each eave. Hips and valleys do not change the area, but they raise waste and add lineal feet.
Fictional example: a 6 in 12 shingle roof
Fictional example. A roofer is pricing a 50 x 30 ft gable roof at 6 in 12 with three-bundle shingles and 10% waste.
- Plan area: 50 x 30 = 1,500 SF
- Pitch multiplier at 6 in 12: 1.118
- Roof surface: 1,500 x 1.118 = 1,677 SF, or 16.77 squares
- With waste: 18.45 squares
- Bundles: 18.45 x 3 = 55.3, so order 56 bundles
A low slope check: a 200 x 100 ft roof at 1/4 in 12 is 20,004 SF, or 200.04 squares. With 5% waste and 1,000 SF net per roll, that is 22 membrane rolls. The roofing cost per square foot comes from the roofer’s own rates divided by roof surface area.
What drives roofing cost per square foot?
Roofing cost per square foot depends on the system, the roof’s shape and access, and what is coming off. We do not publish a national average because no sourced figure fits every system and market.
Price these drivers instead:
- System. Asphalt shingle, standing seam metal, tile, TPO, PVC, EPDM, modified bitumen and built-up roofs all price differently.
- Pitch and height. Steep and tall roofs need fall protection, staging and slower production.
- Complexity. Hips, valleys, dormers, penetrations and short runs raise waste and labor.
- Tear-off. Number of existing layers, deck repair and disposal.
- Insulation. On low slope roofs, roof insulation and tapered systems can cost as much as the membrane.
- Flashing and sheet metal. Edge metal, coping, counterflashing and curbs.
- Warranty. Manufacturer warranty requirements can add materials and inspection.
With your own unit costs per square, the calculator reports a cost per square and per square foot you can stand behind.
What this roofing calculator does not cover
This tool measures roof area and the main material counts. A commercial roofing estimate has more parts, and these are the common misses:
- Tapered insulation layouts, crickets and saddles
- Cover board and multiple insulation layers by thickness
- Edge metal, coping, gutters and downspouts by profile
- Base flashing and counterflashing at walls, curbs and penetrations
- Roof drains, overflow drains and scuppers
- Mechanical curbs and pipe penetrations from the mechanical roof plan
- Walkway pads and fall protection
- Different roof areas with different systems on one building
A plan-based takeoff measures each roof area from the roof plan, details and specification. See roofing estimating for what Bidmere measures.
When a roofing estimator is not enough
A calculator is right for a single residential roof or a quick check. A commercial roofing bid needs every area, layer and detail measured from the drawings.
Bidmere prepares roofing takeoffs and estimates from your plans and specifications. We measure membrane and insulation by roof area, edge and flashing lengths by detail, and drains, curbs and penetrations by type. Quantities are priced at your rates. Single-trade estimates are from $195 and ready in 48 hours after you accept a fixed quote. You get an Excel estimate with live formulas, color-coded marked-up PDF plans, and a written list of assumptions, exclusions and open questions.
Sample takeoff
What a takeoff looks like
| Item | Quantity | Unit | Note |
|---|---|---|---|
| Plan area | 1,500 | SF | 50 x 30 ft |
| Pitch multiplier | 1.118 | 6 in 12 | |
| Roof surface | 1,677 | SF | 16.77 squares net |
| Squares with waste | 18.45 | SQ | 10% waste |
| Shingle bundles | 56 | EA | 3 bundles per square |
Fictional example: 50 x 30 ft gable roof at 6 in 12
Before you send plans
Common questions about handing off the work
Why does the estimator not show a price per square?
Because material, labor and tear-off costs vary by system and market. Your own rates give a defensible number.
Can I bid a commercial roof from this?
Use it to check areas. Tapered insulation, flashing, edge metal and penetrations need a measured takeoff.
Who signs and submits the bid?
You do. Bidmere prepares quantities and pricing at your rates; you set markup and submit.
Questions
Frequently asked questions
How do you calculate roofing squares?
Measure the roof’s horizontal plan area, including overhangs. Multiply by the pitch multiplier, which is the square root of 1 plus rise over 12, squared. Divide by 100 to get squares. A 1,500 SF plan at 6 in 12 is 1,500 x 1.118 = 1,677 SF, or 16.77 squares. Then add waste.
How do you calculate roofing cost per square foot?
Total the material, labor, tear-off, flashing and equipment costs for the roof. Divide by the roof surface area, not the plan area. Contractors often quote per square, which is the same total divided by the number of 100 SF squares. Enter your own rates in the roofing estimator and it shows both.
How much waste should a roofing estimate include?
It depends on the roof’s shape. A simple gable wastes less than a cut-up roof with hips, valleys and dormers, because each cut leaves scrap. Use your own job history for similar roofs. The calculator starts at 10% for shingles. Low slope membrane waste depends on roll width, seam layout and penetrations.
How many bundles of shingles are in a square?
Many architectural and three-tab shingles come three bundles to a square. Some heavier products need four or more. Check the wrapper or the manufacturer’s data for the product you are pricing, and enter that figure in the calculator. Hip and ridge cap is usually a separate product priced by the lineal foot.
What is a roofing estimate based on for commercial work?
A commercial roofing estimate is built from the roof plan, roof details, specification and mechanical roof plan. It measures membrane and insulation by area and layer, edge metal and flashing by lineal foot, and drains, curbs and penetrations by count. Each quantity is priced with labor and material rates, then marked up.
Does the roofing estimator save my inputs?
No. The calculator runs in your browser and does not send or store what you enter. Use the copy results button to paste the quantities, costs and inputs into your estimate, a spreadsheet or an email. Reset defaults clears your entries and restores the starting assumptions.
Can Bidmere prepare my roofing estimate from plans?
Yes. Send the plans and specifications for a free plan review and a fixed quote within 2 business hours. Single-trade roofing estimates are from $195 and ready in 48 hours after you accept. We measure each roof area and detail and price them at your rates. You pay only after you accept the price and delivery date.
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Share the project basics. You get a fixed price and delivery date within 2 business hours. Plan review is free, and you pay only after you accept.