{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"roof-shingles"},"result":{"entity_type":"calculator","id":"roof-shingles","calculator_id":"roof-shingles","canonical_url":"https://tttkmbb.com/construction/roof-shingles","name":"Roof Shingle Calculator","title":"Roof Shingle Calculator – Squares, Bundles and Underlayment Rolls from Roof Footprint and Pitch","category":"construction","category_name":"Construction & Home","tool_name":"estimate_roof_shingles","featured_mcp_tool":false,"description":"Estimates asphalt shingles from the roof's horizontal footprint area and pitch: the pitch factor √(1 + (rise/12)²) converts the footprint to sloped surface area, which is expressed in roofing squares (100 ft²), increased by a waste allowance and converted to bundles and underlayment rolls. Planning estimate only.","use_when":"You need the number of shingle bundles, squares or underlayment rolls to order for a pitched roof whose plan area and pitch (x:12 or degrees) are known.","do_not_use_when":"You only need to convert the pitch or find a rafter length (use roof-pitch), or the roof is metal, tile or membrane sold by the sheet (divide roof_surface_area_ft2 by the panel coverage instead).","inputs":[{"name":"roof_footprint_area","label":"Roof footprint area","type":"number","unit":"ft² or m²","required":true,"max":1000000,"exclusive_min":0,"description":"Horizontal (plan) area covered by the roof including eave overhangs, in ft² or m² (see area_unit); for a simple gable roof this is the building length × width plus overhangs.","example":1500},{"name":"area_unit","label":"Area unit","type":"enum","required":false,"default":"ft2","values":[{"value":"m2","label":"Square metres (m²)","aliases":["m²","sqm","square metres","square meters","metric"]},{"value":"ft2","label":"Square feet (ft²)","aliases":["ft²","sqft","square feet","imperial"]}],"description":"Unit of the area input; areas are reported in both m² and ft².","example":"ft2"},{"name":"pitch_rise_per_12","label":"Pitch (rise per 12)","type":"number","required":false,"default":6,"min":0,"max":24,"description":"Roof pitch as rise per 12 units of run (6 means 6:12); ignored when pitch_degrees is given.","example":6},{"name":"pitch_degrees","label":"Pitch (degrees)","type":"number","unit":"°","required":false,"min":0,"max":85,"description":"Roof angle from horizontal in degrees; overrides pitch_rise_per_12 when given."},{"name":"waste_percent","label":"Waste allowance","type":"number","unit":"%","required":false,"default":10,"min":0,"max":50,"description":"Extra material for cuts, breakage and offcuts, applied as a multiplier (1 + waste_percent/100). 10 % for simple gable roofs; 15 % for hip roofs, dormers and valleys.","example":10},{"name":"bundles_per_square","label":"Bundles per square","type":"number","required":false,"default":3,"max":10,"exclusive_min":0,"description":"Bundles that cover one square (100 ft²): 3 for three-tab and most laminated (architectural) shingles, 4–5 for heavy designer shingles; printed on the bundle.","example":3},{"name":"underlayment_coverage_ft2_per_roll","label":"Underlayment coverage per roll","type":"number","unit":"ft²","required":false,"default":400,"max":5000,"exclusive_min":0,"description":"Net coverage of one roll of underlayment in ft²: about 400 ft² (4 squares) for a #15 felt roll and for 4-square synthetic rolls, 200 ft² (2 squares) for #30 felt, 1,000 ft² (10 squares) for many synthetic rolls.","example":400}],"outputs":[{"name":"pitch_factor","label":"Pitch factor","type":"number","decimals":4,"description":"√(1 + (rise/12)²) = 1 / cos(roof angle): sloped area per unit of plan area."},{"name":"roof_angle_degrees","label":"Roof angle","type":"number","unit":"°","decimals":2,"description":"atan(rise / 12)."},{"name":"roof_surface_area_ft2","label":"Roof surface area","type":"number","unit":"ft²","decimals":1,"description":"Footprint area × pitch_factor."},{"name":"roof_surface_area_m2","label":"Roof surface area","type":"number","unit":"m²","decimals":2,"description":"Same sloped area in square metres."},{"name":"squares","label":"Roofing squares","type":"number","decimals":2,"description":"roof_surface_area_ft2 / 100 (1 square = 100 ft² = 9.29 m²)."},{"name":"squares_with_waste","label":"Squares to order","type":"number","decimals":2,"description":"squares × (1 + waste_percent/100)."},{"name":"bundles","label":"Bundles to buy","type":"integer","decimals":4,"description":"ceil(squares_with_waste × bundles_per_square)."},{"name":"underlayment_rolls","label":"Underlayment rolls","type":"integer","decimals":4,"description":"ceil(squares_with_waste × 100 / underlayment_coverage_ft2_per_roll)."},{"name":"ridge_cap_note","label":"Ridge and hip caps","type":"string","decimals":4,"description":"Reminder that hip and ridge cap shingles are estimated separately by linear length."}],"input_schema":{"type":"object","properties":{"roof_footprint_area":{"description":"Horizontal (plan) area covered by the roof including eave overhangs, in ft² or m² (see area_unit); for a simple gable roof this is the building length × width plus overhangs. Unit: ft² or m².","type":"number","maximum":1000000,"exclusiveMinimum":0,"examples":[1500],"x-unit":"ft² or m²"},"area_unit":{"description":"Unit of the area input; areas are reported in both m² and ft².","type":"string","enum":["m2","ft2"],"default":"ft2","examples":["ft2"]},"pitch_rise_per_12":{"description":"Roof pitch as rise per 12 units of run (6 means 6:12); ignored when pitch_degrees is given.","type":"number","minimum":0,"maximum":24,"default":6,"examples":[6]},"pitch_degrees":{"description":"Roof angle from horizontal in degrees; overrides pitch_rise_per_12 when given. Unit: °.","type":"number","minimum":0,"maximum":85,"x-unit":"°"},"waste_percent":{"description":"Extra material for cuts, breakage and offcuts, applied as a multiplier (1 + waste_percent/100). 10 % for simple gable roofs; 15 % for hip roofs, dormers and valleys. Unit: %.","type":"number","minimum":0,"maximum":50,"default":10,"examples":[10],"x-unit":"%"},"bundles_per_square":{"description":"Bundles that cover one square (100 ft²): 3 for three-tab and most laminated (architectural) shingles, 4–5 for heavy designer shingles; printed on the bundle.","type":"number","maximum":10,"exclusiveMinimum":0,"default":3,"examples":[3]},"underlayment_coverage_ft2_per_roll":{"description":"Net coverage of one roll of underlayment in ft²: about 400 ft² (4 squares) for a #15 felt roll and for 4-square synthetic rolls, 200 ft² (2 squares) for #30 felt, 1,000 ft² (10 squares) for many synthetic rolls. Unit: ft².","type":"number","maximum":5000,"exclusiveMinimum":0,"default":400,"examples":[400],"x-unit":"ft²"}},"additionalProperties":false,"required":["roof_footprint_area"]},"output_schema":{"type":"object","properties":{"pitch_factor":{"description":"√(1 + (rise/12)²) = 1 / cos(roof angle): sloped area per unit of plan area.","type":"number"},"roof_angle_degrees":{"description":"atan(rise / 12). Unit: °.","type":"number","x-unit":"°"},"roof_surface_area_ft2":{"description":"Footprint area × pitch_factor. Unit: ft².","type":"number","x-unit":"ft²"},"roof_surface_area_m2":{"description":"Same sloped area in square metres. Unit: m².","type":"number","x-unit":"m²"},"squares":{"description":"roof_surface_area_ft2 / 100 (1 square = 100 ft² = 9.29 m²).","type":"number"},"squares_with_waste":{"description":"squares × (1 + waste_percent/100).","type":"number"},"bundles":{"description":"ceil(squares_with_waste × bundles_per_square).","type":"integer"},"underlayment_rolls":{"description":"ceil(squares_with_waste × 100 / underlayment_coverage_ft2_per_roll).","type":"integer"},"ridge_cap_note":{"description":"Reminder that hip and ridge cap shingles are estimated separately by linear length.","type":"string"}}},"formula":"pitch_factor = √(1 + (pitch_rise_per_12 / 12)²) (or 1 / cos(pitch_degrees)); roof_surface_area = roof_footprint_area × pitch_factor; squares = area_ft² / 100; squares_with_waste = squares × (1 + waste_percent/100); bundles = ceil(squares_with_waste × bundles_per_square); underlayment_rolls = ceil(squares_with_waste × 100 / underlayment_coverage_ft2_per_roll).","method":"The footprint is measured in plan, so the pitch factor (the rafter multiplier of roof-pitch) recovers the true sloped area of every plane at that pitch; starter strips, hip and ridge caps, drip edge, flashing and nails are not included. Planning estimate only; check quantities against the supplier's coverage figures and local code before ordering.","sources":[{"name":"Wikipedia – Roof pitch","url":"https://en.wikipedia.org/wiki/Roof_pitch","type":"reference","retrieved_at":"2026-09-24"},{"name":"Wikipedia – Asphalt shingle","url":"https://en.wikipedia.org/wiki/Asphalt_shingle","type":"reference","retrieved_at":"2026-09-24"},{"name":"Wikipedia – Roof shingle","url":"https://en.wikipedia.org/wiki/Roof_shingle","type":"reference","retrieved_at":"2026-09-24"}],"freshness":{"type":"static","max_age_seconds":null,"note":"Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output."},"examples":[{"name":"1,500 ft² footprint, 6:12 pitch, 10 % waste, 3 bundles per square, 400 ft² rolls","inputs":{"roof_footprint_area":1500,"area_unit":"ft2","pitch_rise_per_12":6,"waste_percent":10,"bundles_per_square":3,"underlayment_coverage_ft2_per_roll":400},"expected":{"pitch_factor":1.118,"roof_angle_degrees":26.57,"roof_surface_area_ft2":1677.1,"roof_surface_area_m2":155.8,"squares":16.77,"squares_with_waste":18.45,"bundles":56,"underlayment_rolls":5},"url":"https://tttkmbb.com/api/v1/calculate/roof-shingles?roof_footprint_area=1500&area_unit=ft2&pitch_rise_per_12=6&waste_percent=10&bundles_per_square=3&underlayment_coverage_ft2_per_roll=400"},{"name":"140 m² footprint, 30° pitch, 15 % waste, 1,000 ft² synthetic rolls","inputs":{"roof_footprint_area":140,"area_unit":"m2","pitch_degrees":30,"waste_percent":15,"underlayment_coverage_ft2_per_roll":1000},"expected":{"pitch_factor":1.1547,"roof_surface_area_m2":161.66,"roof_surface_area_ft2":1740.1,"squares":17.4,"squares_with_waste":20.01,"bundles":61,"underlayment_rolls":3},"url":"https://tttkmbb.com/api/v1/calculate/roof-shingles?roof_footprint_area=140&area_unit=m2&pitch_degrees=30&waste_percent=15&underlayment_coverage_ft2_per_roll=1000"}],"faq":[{"q":"Do I measure the footprint or the sloped roof?","a":"Enter the horizontal footprint (building plan plus overhangs); the pitch factor converts it to sloped area. If you already measured the sloped area, enter it with pitch_rise_per_12 = 0."},{"q":"How many bundles are in a square?","a":"Three bundles per square is standard for three-tab and most laminated shingles (about 33 ft² per bundle); heavier designer shingles need 4–5, so check the bundle label."},{"q":"Why does the roll count use the waste figure?","a":"Underlayment is lapped 2–4 in horizontally and 6 in at end joints and is cut at hips and valleys, so the waste-inclusive area keeps the roll count conservative."}],"tags":["roof shingle calculator","shingle bundles","roofing squares","how many bundles of shingles","underlayment rolls","roof area"],"related":[{"calculator_id":"roof-pitch","reason":"Convert the pitch and get the rafter multiplier."},{"calculator_id":"right-triangle","reason":"Sloped length of a roof plane from rise and run."}],"links":{"html":"https://tttkmbb.com/construction/roof-shingles","markdown":"https://tttkmbb.com/construction/roof-shingles.md","json":"https://tttkmbb.com/construction/roof-shingles.json","api":"https://tttkmbb.com/api/v1/calculate/roof-shingles","schema":"https://tttkmbb.com/api/v1/calculators/roof-shingles","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-24"},"timestamp":"2026-09-24T03:49:15Z","next_actions":[{"tool":"run_calculator","calculator_id":"roof-shingles","reason":"Run Roof Shingle Calculator with the inputs above."}],"links":{"markdown":"https://tttkmbb.com/construction/roof-shingles.md"}}