Roofing calculator

Give this roofing calculator the footprint of the house and the pitch, and it returns the sloped roof area in square feet and m², the roofing squares and the shingle bundles to buy. Roof area is the footprint multiplied by a pitch factor, and one roofing square is 100 sq ft (9.29 m2). Most shingles come 3 bundles to a square, but several popular lines cover only 98.4 sq ft per square, so the product matters.

By BuildersCalcs editorial team Updated Formula and constants sourced, see below

Roofing calculator

v1 · US and metric

Enter the roof footprint and pitch, or a measured roof area, plus the edge lengths. The result gives the sloped roof area, roofing squares, shingle bundles for the product you pick, nails, underlayment rolls, starter and ridge cap bundles and drip edge.

Units
Measurements
ft

Measure the house along the eaves and add the overhang at each end. ARMA does not recommend homeowners climb onto a roof to measure; measure from the ground or use a professional.

Enter a number from 1 to 1000 ft.

ft

Eave to eave across the house, level, with both overhangs.

Enter a number from 1 to 1000 ft.

sq ft

The sloped area of all roof planes, for example from a survey or report.

Enter a number from 10 to 200000 sq ft.

Options

Used for the area in footprint mode and for the slope checks in both modes. The roof pitch calculator converts a measured rise and run.

Enter a number from 0 to 80.

GAF Timberline HDZ: 3 bundles (one of 20 shingles and two of 22) cover 98.4 sq ft (9.14 m2). Owens Corning Duration Premium is packed 4 bundles per square (98.4 sq ft); heavier shingles need more bundles. Owens Corning Supreme 3-tab: 12 x 36 in, 5 in exposure, about 80 shingles and 100 sq ft per 3 bundles. Check the bundle wrapper for the product you buy.

sq ft

Printed on the bundle wrapper. Only used when the product is Other.

Enter a number from 5 to 100 sq ft.

GAF standard nailing pattern is 4 nails per shingle; the enhanced pattern is 6 nails.

TAMKO No. 15 ASTM felt: 36 in x 144 ft roll (0.91 x 43.9 m) rated at 4 squares (400 sq ft, 37.2 m2). TAMKO No. 30 ASTM felt: 36 in x 72 ft roll (0.91 x 21.9 m) rated at 2 squares (200 sq ft, 18.6 m2). GAF FeltBuster synthetic: 48 in x 250 ft (1.23 x 76.2 m) roll covers 1,000 sq ft (92.9 m2), 10 squares, excluding laps.

ft

All the lower, level roof edges added together. A simple gable roof has two.

Enter a number from 0 to 5000 ft.

ft

All the sloped gable edges added together, measured along the slope. A hip roof has none.

Enter a number from 0 to 5000 ft.

ft

Enter a number from 0 to 5000 ft.

%

ARMA: most roofs need 2% to 10% extra shingles for trim waste, rising with valleys, dormers, hips and penetrations. Guertin: gable-end fall-off, valley trimmings and damaged shingles can add up to about 5%.

Enter a number from 0 to 30 %.

Result

–

Enter your measurements and press Calculate.

Formula and assumptions
  • Footprint from the ground, plus pitch: Roof area (sq ft) = length (ft) × width (ft) × pitch factor, where pitch factor = √(rise² + 12²) ÷ 12; metric: Roof area (m²) = length (m) × width (m) × pitch factor, where pitch factor = √(rise² + 12²) ÷ 12
  • Squares = roof area ÷ 100 sq ft; bundles = roof area × (1 + waste) ÷ (coverage per square ÷ bundles per square), rounded up; metric: Squares = roof area (converted to sq ft) ÷ 100; bundles = area × (1 + waste) ÷ coverage per bundle, rounded up
  • Nails = area with waste ÷ coverage per square × shingles per square × nails per shingle
  • Underlayment rolls = roof area × layers ÷ net roll coverage; starter bundles = (eaves + rakes) ÷ starter length per bundle; ridge bundles = (ridges + hips) ÷ ridge length per bundle; drip edge pieces = (eaves + rakes) ÷ (piece length − overlap); metric: Same rules, with lengths converted from m to ft
  • One roofing square is 100 sq ft of roof surface. Three bundles of Timberline HDZ cover 98.4 sq ft, not a full 100 sq ft.
  • Shingle packaging: Owens Corning Duration Premium is packed 4 bundles per square (98.4 sq ft); heavier shingles need more bundles. Owens Corning Supreme 3-tab: 12 x 36 in, 5 in exposure, about 80 shingles and 100 sq ft per 3 bundles. Three bundles per square is the most common packaging, but some products use 4 or 5.
  • Nails: GAF standard nailing pattern is 4 nails per shingle; the enhanced pattern is 6 nails. IRC R905.2.6: at least 4 fasteners per strip shingle (2 per individual shingle), or more if the manufacturer requires.
  • Underlayment roll coverage is the maker's net figure after laps: TAMKO No. 15 ASTM felt: 36 in x 144 ft roll (0.91 x 43.9 m) rated at 4 squares (400 sq ft, 37.2 m2). GAF FeltBuster synthetic: 48 in x 250 ft (1.23 x 76.2 m) roll covers 1,000 sq ft (92.9 m2), 10 squares, excluding laps. From 2:12 up to 4:12 the IRC requires double underlayment under shingles (R905.2.2 / R905.1.1).
  • GAF instructs starter strip shingles along both eaves and rakes, so starter length = eaves + rakes. GAF Pro-Start starter: 19 full sheets (38 pieces, 13 x 38 in) cover about 120.33 lin ft (36.68 m) per bundle. Owens Corning Starter Strip and Starter Strip Plus: 16 shingles, about 100 lin ft (30.5 m) per bundle.
  • Hip and ridge: GAF Seal-A-Ridge: 4 bundles cover about 100 lin ft (30 m), i.e. about 25 lin ft per bundle. Owens Corning ProEdge Hip & Ridge: 22 shingles (66 pieces) at 6 in exposure cover 33 lin ft (10.1 m) per bundle.
  • Drip edge: IRC R905.2.8.5: drip edge is required at eaves and rakes; adjoining pieces overlap at least 2 in (51 mm). Drip edge is commonly sold in 10 ft (3.05 m) lengths.
  • Ice barrier, valley lining and flashings are not counted. Where required, the IRC ice barrier runs from the eave to at least 24 in (610 mm) inside the exterior wall line.

How many bundles of shingles does a 40 × 30 ft house need?

A 40 ft by 30 ft gable house with a 6 in 12 roof has 1,341.6 sq ft (124.6 m²) of roof surface, or 13.42 squares. With the default 10% extra that becomes 14.76 squares, which is 45 bundles of GAF Timberline HDZ. Those are the figures the calculator shows when it loads, along with 3,840 nails, 2 rolls of synthetic underlayment, 2 starter bundles, 2 ridge cap bundles and 15 lengths of drip edge.

Measure the footprint level, from the ground, and include the overhangs: the eave side of the house plus the overhang at each gable end, then eave to eave across. ARMA does not recommend homeowners climb onto a roof to measure; measure from the ground or use a professional. Our guide to measuring a roof from the ground shows how to read the pitch from the gable end too. If you already know the surface area from a survey or an old invoice, switch to the known-area mode; the pitch still matters there, because it drives the slope checks and the underlayment layers.

The edge boxes drive the accessories. Eaves are the level bottom edges where gutters hang, rakes are the sloped gable edges measured along the slope, and ridges and hips are the lines that get capped. A hip roof has eaves on all four sides and no rakes.

How is roof square footage calculated from the footprint?

Roof square footage is the footprint area multiplied by the pitch factor, √(rise² + 12²) ÷ 12, which is the sloped length for every 12 units of level run. The roof pitch calculator gives the same factor from a measured rise and run or an angle. Every count then follows from one division:

  • Squares: roof area (sq ft) × (1 + waste %) ÷ 100. Metric areas are converted to square feet first.
  • Bundles: area with waste ÷ coverage per bundle, rounded up, where coverage per bundle is the maker's square coverage ÷ its bundles per square.
  • Nails: area with waste ÷ coverage per square × shingles per square × nails per shingle.
  • Underlayment: roof area × layers ÷ net roll coverage, rounded up.
  • Starter and drip edge: eaves + rakes, divided by the length per bundle or per piece (less the overlap). Ridge cap: ridges + hips ÷ length per bundle.

Worked example: the default gable roof

The pitch factor for 6 in 12 is √(36 + 144) ÷ 12 = 1.118, so 40 ft × 30 ft × 1.118 = 1,341.6 sq ft. Add 10%: 1,475.8 sq ft, or 14.76 squares. Timberline HDZ covers 98.4 sq ft with 3 bundles, so one bundle covers 32.8 sq ft, and 1,475.8 ÷ 32.8 = 44.99, rounded up to 45 bundles. Nails: 1,475.8 ÷ 98.4 × 64 shingles × 4 = 3,840. One FeltBuster roll covers 10 squares, so 2 rolls. The 147 ft of eaves and rakes needs 2 bundles of Pro-Start at 120.33 lin ft each, and the 40 ft ridge 2 bundles of Seal-A-Ridge.

In metric, a 12 m by 9 m footprint at 30° is 6.93 in 12 with a factor of 1.1547, giving 124.7 m² (1,342.3 sq ft). With Owens Corning Supreme and the six-nail pattern that is 45 bundles and 7,088 nails.

Worked examples from the calculator (results as the calculator shows them)
RoofInputsWasteRoof areaShingle bundlesOther items
Gable, US defaults40 × 30 ft footprint, 6 in 12, GAF Timberline HDZ10%1,341.6 sq ft (124.6 m²), 13.42 squares453,840 nails, 2 synthetic rolls, 2 starter, 2 ridge, 15 drip edge
Known area2,000 sq ft, Owens Corning Duration Premium, No. 15 felt, 100 ft eaves, 60 ft ridge5%2,000 sq ft (185.8 m²), 20 squares865,464 nails, 5 felt rolls, 1 starter, 2 ridge, 11 drip edge
Low slope40 × 30 ft footprint, 3 in 12, No. 30 felt10%1,236.9 sq ft (114.9 m²)4213 felt rolls for two layers
Metric12 × 9 m footprint, 30°, Owens Corning Supreme, six nails10%124.7 m² (1,342.3 sq ft)457,088 nails, 15 drip edge

How many bundles of shingles are in a square?

Three bundles make a square for most shingles, but not all, and a three-bundle square does not always cover a full 100 sq ft. GAF Timberline HDZ: 3 bundles (one of 20 shingles and two of 22) cover 98.4 sq ft (9.14 m2). Owens Corning Duration Premium is packed 4 bundles per square (98.4 sq ft); heavier shingles need more bundles. Owens Corning Supreme 3-tab: 12 x 36 in, 5 in exposure, about 80 shingles and 100 sq ft per 3 bundles. (GAF, Owens Corning / Lowe's and others)

The gap compounds: on a 30-square roof, counting a 98.4 sq ft product as if it covered a full square leaves you about half a square short. That is why the calculator divides by the printed coverage. For an unlisted shingle, choose Other and type the coverage per bundle from the wrapper; nails are then left out, because the calculator no longer knows the shingles per square. CertainTeed Landmark has no bundle count in the table because the data sheet we retrieved does not give one.

Shingle packaging by named product (check the bundle wrapper for the product you buy)
ProductTypeSize (in)Exposure (in)Shingles per squareBundles per squareCoverage per square (sq ft)Source
GAF Timberline HDZarchitectural13-1/4 x 39-3/85.62564398.4gaf-hdz-ii / gaf-hdz-ds
Owens Corning TruDefinition Durationarchitectural13-1/4 x 39-3/85.62564398.4Owens Corning / Lowe's
Owens Corning Duration Premiumarchitectural13-1/4 x 39-3/85.62564498.4Owens Corning / Lowe's
CertainTeed Landmarkarchitectural13-1/4 x 38-3/45.62566NoneNoneCertainTeed
Owens Corning Supreme3-tab12 x 365803100Owens Corning

How much underlayment, starter and ridge cap does a roof need?

Underlayment comes from the roof area; starter, ridge cap and drip edge come from edge lengths. ARMA: starter, drip edge, hip/ridge and valley flashing are estimated from eave, rake, hip, ridge and valley lengths. Roll coverage varies widely: A 10-square synthetic roll replaces about 2.5 rolls of #15 felt or 5 rolls of #30. These are the makers' net figures after laps, so no lap allowance is added. Slope changes the count, because From 2:12 up to 4:12 the IRC requires double underlayment under shingles (R905.2.2 / R905.1.1). On the 3 in 12 example above, No. 30 felt jumps to 13 rolls.

GAF instructs starter strip shingles along both eaves and rakes, so starter length = eaves + rakes. The calculator uses eaves plus rakes for the Owens Corning starter as well, which is the safe side if your installer starts the rakes. Cap coverage differs by product: GAF's Seal-A-Ridge covers about 25 lin ft per bundle and Owens Corning's ProEdge 33 lin ft. Drip edge is commonly sold in 10 ft (3.05 m) lengths. IRC R905.2.8.5: drip edge is required at eaves and rakes; adjoining pieces overlap at least 2 in (51 mm). The overlap comes off each piece before dividing.

A roof plan uses distinct line treatments for eaves, rakes and ridge, showing how accessory lengths come from edges rather than roof area.
Make a separate linear takeoff for starter, ridge caps and edge details. Original illustration by BuildersCalcs. CC BY 4.0.
Illustration sources
Underlayment roll coverage (net, as stated by manufacturer)
ProductTypeWidth (in)Length (ft)Net squares per rollNet m² per rollSource
TAMKO No. 15 ASTMfelt ASTM D226 Type I36144437.2TAMKO
TAMKO No. 30 ASTMfelt ASTM D226 Type II3672218.6TAMKO
GAF FeltBustersynthetic482501092.9GAF
Starter and hip/ridge cap coverage per bundle
ProductUseLin ft per bundleLin m per bundleSource
GAF Pro-Startstarter120.3336.68GAF
Owens Corning Starter Strip / Starter Strip Plusstarter10030.48Owens Corning / Lowe's
Owens Corning ProEdge Hip & Ridgehip/ridge3310.06Owens Corning
GAF Seal-A-Ridgehip/ridge257.62GAF

How many roofing nails per square?

Nails per square are shingles per square times nails per shingle. GAF lists 256 nails per square for Timberline HD (4 per shingle), 384 where 6 nails per shingle are required. The calculator scales that by your area with waste and by the product you pick, so Supreme 3-tab, at about 80 shingles per square, needs more nails than an architectural shingle on the same roof. IRC R905.2.6: at least 4 fasteners per strip shingle (2 per individual shingle), or more if the manufacturer requires. Choose the enhanced pattern where your code, the shingle warranty or a high-wind zone calls for it; the calculator cannot decide that, because the wind-speed thresholds in the current IRC table were not available to us.

How much extra shingle should you allow for waste?

ARMA: most roofs need 2% to 10% extra shingles for trim waste, rising with valleys, dormers, hips and penetrations. The calculator starts at the top of that range, which suits a roof with valleys, dormers or hips; lower it for a plain two-plane gable. Fine Homebuilding's Mike Guertin frames it differently: Guertin: gable-end fall-off, valley trimmings and damaged shingles can add up to about 5%. ARMA's range is about roof shape, while Guertin's figure also counts damaged pieces.

You will often read that a gable needs 10% and a hip roof 15%. We found that split in no manufacturer, ARMA or NRCA document, so the calculator does not offer it. The waste allowance by material guide sets shingles beside the other materials. Nationally, the waste adds up: EPA estimates 1.2 million tons of asphalt shingles were wasted during US construction in 2018, against 13.9 million tons from demolition and tear-off. These 2018 EPA estimates are the latest of their kind.

Does the roofing calculator work for metric and UK roofs?

Yes for the area, partly for the materials. In metric mode you enter metres and can give the pitch in degrees, as UK drawings do. UK roof tile data sheets state minimum pitch in degrees (e.g. 17.5 deg, 35 deg), not x:12. The shingle, underlayment and accessory products stay the US ones, because we found no sourced packaging data for shingles sold in the UK or EU.

For a tiled UK roof, take the m² result and divide by the tile maker's coverage instead of using the bundle count. Coverage depends on the headlap or gauge, which depends on pitch and exposure. UK slating and tiling is governed by BS 5534 (code of practice); Redland cites BS 5534:2014+A2:2018. No manufacturer waste figure for UK tiling was available, so ask the merchant what they allow for cuts.

UK roof tiles: coverage, battens and minimum pitch
TileSize (mm)Headlap or gaugeTiles per m²Batten (lin m per m²)Minimum pitch (°)Source
Marley Modern420 x 33075 mm headlap (345 gauge)9.92.922.5 smooth / 30 granularMarley (UK)
Marley Modern420 x 330100 mm headlap10.73.117.5 smooth / 25 granularMarley (UK)
Redland 49382 x 226282 mm gauge17.7None17.5-30 by finish/lapBMI Redland (UK)
Redland 49382 x 226307 mm gauge16.33.2617.5-30 by finish/lapBMI Redland (UK)
Marley concrete plain tile267 x 168100 mm gauge (65 mm headlap)601035Marley (UK)

How often do people get hurt on ladders and roofs?

Often enough that a ground measurement is worth a small loss of precision. An estimated 189,731 people (95% CI 152,918–226,543) were treated in US hospital emergency departments in 2025 for injuries involving ladders (stepladders, straight, extension and other ladders; codes 618, 619, 688, 4032, 4033, 4077, 4078), per our analysis of CPSC NEISS data. An estimated 7,317 people (95% CI 5,224–9,410) were treated in US hospital emergency departments in 2025 for injuries involving falls from or onto a roof, identified from the case narrative because NEISS has no roof product code, per our analysis of CPSC NEISS data. Narratives are short, so this is a lower bound. Roof falls are the more serious of the two: 26.2% of people treated in US emergency departments in 2025 after a narrative-identified roof fall were admitted to hospital, about twice the 12.8% for stair injuries (1,920 of the national estimate, 95% CI 1,152–2,688), per our analysis of CPSC NEISS 2025 data. These NEISS estimates include homeowners and workers alike.

Trained crews are not immune. Falls, slips and trips accounted for 96 of the 120 fatal work injuries among US roofing contractors in 2024, or 80% (BLS CFOI). For ladders at work, Work-related ladder falls killed 113 US workers in 2011 and caused an estimated 34,000 emergency department visits, per NIOSH's MMWR analysis, still the latest national cross-source study of its kind. Our page of DIY injury data from NEISS breaks the figures down further.

When is the roofing calculator's answer wrong?

The calculator assumes one pitch for every plane and a footprint that describes the whole roof. Real roofs often break that:

  • Mixed pitches. A shallow porch roof on a steeper main roof needs one run per pitch, added together.
  • Dormers. The dormer roof sits on top of the main roof, so run it separately or use a measured total area.
  • Below the shingle minimum. Under IRC R905.2.2 asphalt shingles may only be used on slopes of 2:12 (17%) or steeper. The calculator prints a warning; look at the metal roofing calculator or a membrane instead.
  • Very steep roofs. Above about 21:12 (60 degrees, mansard) manufacturers require 6 nails plus hand-sealing.
  • Uncounted items. Ice barrier, valley lining, flashings, vents and sheathing. Where required, the IRC ice barrier runs from the eave to at least 24 in (610 mm) inside the exterior wall line.
  • Overlays. IRC R908.3.1.1: no roof recover where the roof already has two or more applications of covering.

With the roof off, it is also a good moment to check the loft; the calculator for batts or rolls of insulation counts packages or blown-in bags by climate zone.

A roof-plane schematic marks the main-roof cutout and the two added dormer slopes, preventing both omission and double counting.
Do not count the hidden main-roof patch and the dormer roof as the same surface. Original illustration by BuildersCalcs. CC BY 4.0.
Illustration sources

How many homeowners replace a roof each year?

About 4.15 million US homeowners reported roofing replacement projects in 2023, totalling about $45.8 billion, the largest single exterior replacement category (Harvard JCHS Table A-1, 2023 AHS). Prices have climbed since 2020: US producer prices for prepared asphalt roofing and siding products were 47.0% above the 2020 average in September 2026 and 2.7% higher than a year earlier (BLS PPI). That index tracks manufacturers' prices, not a bundle at the lumber yard, but it shows why the calculator stores no prices. To weigh coverings rather than count them, see shingles vs metal vs tile. Every roof tool and chart sits in the roof category.

Roofing calculator questions

How do I convert roof square feet into roofing squares?

Divide the sloped roof area by 100, so a 2,000 sq ft roof is 20 squares before waste. In metric, divide m² by 9.29. Never use the floor area of the house.

Why is my roof area bigger than the floor area of my house?

The roof slopes, so its surface is longer than the level span, and it overhangs the walls. A 6 in 12 roof adds about 12% for the slope alone, before the overhangs.

Does the bundle count include the starter row and the ridge?

No. Shingle bundles cover the field of the roof. Starter and hip-and-ridge products are separate, counted from the edge lengths you enter, and drop to zero if those boxes are empty.

Can I use this calculator for a hip roof?

Yes. A hip roof with the same footprint and pitch as a gable has the same surface area. Set the rake length to zero, put all four hips plus the ridge in the ridge-and-hip box, and allow more waste for the angled cuts.

How many rolls of underlayment for a 20-square roof?

At 4 in 12 and steeper, 2 rolls of GAF FeltBuster, 5 of TAMKO No. 15 or 10 of No. 30, from each maker's net coverage. Between 2 and 4 in 12 the IRC requires two layers, so the counts double.

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Sources (35)
  1. Asphalt Roofing Manufacturers Association (ARMA)
    • Residential Asphalt Roofing Manual - Design and Application Methods, 2014 edition (Ch. 5 Estimating; Ch. 6 Safety), checked
  2. BMI Redland (UK)
    • Redland 49 concrete roof tile technical data sheet (BS EN 490 / BS 5534:2014+A2:2018), checked
  3. CDC NIOSH (MMWR)
    • Occupational Ladder Fall Injuries — United States, 2011 (Socias et al., MMWR 2014;63(16)), checked
  4. CertainTeed
    • Landmark shingles technical data sheet (©03/23), checked
  5. City of Des Moines Permit & Development Center
    • Residential Asphalt Shingle Requirements (2021 IRC Chapter 9, R905.2 and R908.3.1.1), checked
  6. Fine Homebuilding (Taunton Press), Mike Guertin
    • Don't Fall Short on Shingles: How to Estimate Materials for Roofing Projects (excerpt from Roofing with Asphalt Shingles), checked
  7. GAF
    • FeltBuster High-Traction Synthetic Roofing Felt data sheet (©2014, 7/14), checked
    • Installation Instructions: Timberline HDZ, UHDZ, AS II, CS, HDZ RS (©2023, 4/23), checked
    • Pro-Start Starter Strip Shingles sell sheet RESGN546 (4/16), checked
    • Seal-A-Ridge Ridge Cap Shingles sell sheet RESHR112-1223 (©2023), checked
    • Timberline HD Shingles technical data sheet (10/26/2015), checked
    • Timberline HDZ Shingles data sheet (©2019), checked
  8. Health and Safety Executive (UK)
    • Construction - Roof work, checked
  9. Joint Center for Housing Studies of Harvard University
    • Improving America's Housing 2025, checked
  10. K&M Sheet Metal
    • Aluminum 0.027in D-Style Shingle Roof Drip Edge with Kick (10 ft lengths), checked
  11. LSU AgCenter (Louisiana Cooperative Extension Service)
    • Pub. 3104 Consumer's Guide to Code-Compliant Roofing Installations, IRC 2006 Section R905 (03/09), checked
  12. Marley (UK)
    • Concrete Plain Roof Tile - technical data, checked
    • Modern concrete interlocking roof tile - technical data, checked
  13. National Institute of Standards and Technology
    • Handbook 44 (2026), Appendix C: General Tables of Units of Measurement, checked
    • Special Publication 811 (2008), Guide for the Use of the International System of Units (SI), Appendix B.8, checked
  14. Owens Corning
    • Install Instructions: Supreme Shingles (May 2026), checked
    • ProEdge Hip & Ridge Shingles data sheet, Pub. No. 500378-J (December 2025), checked
    • Supreme Shingles product sheet, Pub. No. 10013324-P (February 2026), checked
  15. Owens Corning / Lowe's
    • The Roofing Collection Product Guide (©2017) - Duration, Starter and Hip & Ridge specifications, checked
  16. TAMKO
    • TAMKO No. 15 ASTM Saturated Felt data sheet (Phillipsburg), checked
    • TAMKO No. 30 ASTM Saturated Felt data sheet (Phillipsburg), checked
  17. Town of Firestone, Colorado
    • Reroof Requirements, 2018 IRC (rev 8.11.23), checked
  18. UK Parliament (legislation.gov.uk)
    • Weights and Measures Act 1985, Schedule 1, checked
  19. US Bureau of Labor Statistics
    • CFOI Table A-1. Fatal occupational injuries by industry and event or exposure, all United States, 2024, checked
    • Producer Price Index by commodity (series WPU0811, WPU083, WPU137, WPU1322, WPU1333, WPU1321, WPU1342, WPU1344, WPU1361, WPU1392, WPU0621, WPU1231, WPU1232, WPUIP2321001), checked
  20. US Consumer Product Safety Commission
    • NEISS annual data files 2015–2025 (neiss<year>.xlsx, NEISS_FMT code sheet), checked
  21. US Environmental Protection Agency (EPA), Office of Resource Conservation and Recovery
    • Advancing Sustainable Materials Management: 2018 Fact Sheet, checked
  22. US OSHA (29 CFR via Cornell LII)
    • 29 CFR 1926.1053 Ladders, checked
    • 29 CFR 1926.500 Scope, application and definitions (Subpart M), checked
    • 29 CFR 1926.501 Duty to have fall protection, checked

Every number on this page is taken from these documents. How we choose and check sources.