Glass Thickness Chart (2026): Trade Sizes, Millimetres, Production Ranges and Weight

KEY FINDINGS

What are the key glass thickness statistics?

Four different numbers can all appear beside “quarter-inch glass,” and this glass thickness chart separates them. One quarter of an inch is exactly 6.350 mm. The associated Vitro trade class is 6.0 mm; its nominal reference thickness is 0.223 in, or 5.664 mm; and its published production range is 0.219–0.235 in, or 5.563–5.969 mm. The exact 6.350 mm conversion falls above that range, and 1/4 in is the only one of the eleven fraction-labelled rows in this dataset for which the exact conversion falls outside Vitro’s published range.

These are the page’s fastest quotable findings. Each line identifies the figure, the source vintage and the date this verification pass was completed.

1. One quarter of an inch is exactly 6.350 mm, but Vitro’s 1/4 in row has a published production range of 0.219–0.235 in (5.563–5.969 mm). The exact conversion is above the range. Vitro Architectural Glass TD-120 Rev. 4 (28 November 2024) and NIST; verified July 25, 2026.
2. Of the 11 fraction-labelled rows in this dataset, 1/4 in is the only one whose exact millimetre conversion falls outside the Vitro-published range. Fort Wayne Commercial Glass Repair Research calculation from NIST and Vitro source fields; verified July 25, 2026.
3. One inch equals exactly 25.4 mm under the standard-inch definition effective 1 July 1959 and announced in Federal Register Notice 59-5442. NIST, page updated 19 September 2025; verified July 25, 2026.
4. Vitro TD-120 contains 32 flat-glass reference rows spanning 2.0 mm to 25 mm. The source states that some listed thicknesses may not be available from Vitro. TD-120 Rev. 4; verified July 25, 2026.
5. Two current primary references use different flat-glass density conventions: 157 lb/ft³ in Vitro TD-120 and 156 lb/ft³, or 2,500 kg/m³, in NGA FM05-12 and FB23-25. The U.S. density assumptions differ by 1 lb/ft³, or 0.64% relative to 156 lb/ft³. Verified July 25, 2026.
6. Vitro’s printed table places 0.235 in at the endpoint of both the 6.0 mm and 6.2 mm rows, while its explanatory text assigns 0.235–0.243 in to 6.2 mm. This page preserves that source-level endpoint overlap rather than silently choosing one interpretation. TD-120 Rev. 4; verified July 25, 2026.
7. Five pairs of distinct millimetre classes in TD-120 share the same nominal thickness and published weight: 2.3/2.5 mm, 3.0/3.1 mm, 3.9/4.0 mm, 5.5/6.0 mm and 9.6/10.0 mm. Vitro TD-120 Rev. 4; verified July 25, 2026.
8. A 48 × 96 in lite in the 1/4 in row has a nominal glass-only weight of about 93.4 lb at Vitro’s 157 lb/ft³ convention. Fort Wayne Commercial Glass Repair Research calculation from the TD-120 published weight; verified July 25, 2026.
9. The nominal glass-only weight of the 3/8 in row equals 51 lb at 10.34 ft², a square of about 39 in per side. The 51 lb figure is the NIOSH Revised Lifting Equation load constant under optimal conditions, not a universal one-person lifting limit. Calculation from Vitro and NIOSH Publication No. 94-110, revised September 2021; verified July 25, 2026.
10. NGA publishes design values of 2,800 psi for annealed glass, 5,600 psi for heat-strengthened glass and 11,200 psi for fully tempered glass under the stated short-duration, undamaged, four-sided-support conditions. The latter two are 2× and 4× the annealed design value. NGA FM05-12 (July 2023); verified July 25, 2026.
11. ASTM C1048-25 states that cutting, edgework, drilled holes, notching, grinding, sandblasting and etching must be completed before strengthening or tempering, and that heat-treated flat glass cannot be cut after tempering. ASTM International active standard page; verified July 25, 2026.
12. The current ASTM editions reviewed are C1036-25 for flat glass, C1048-25 for heat-strengthened and fully tempered flat glass, and E1300-24 for load resistance of glass in buildings. ASTM International active-standard pages; verified July 25, 2026.
13. ASTM E1300-24 is not a universal glass-thickness table: its public scope excludes applications including balustrades, glass floors, aquariums, structural glass members and shelves, and says other factors and code criteria may control final type and thickness selection. ASTM International; verified July 25, 2026.
14. Federal safety-glazing impact categories are performance tests, not thickness classes: Category I / ANSI Class B is 150 ft-lb, and Category II / ANSI Class A is 400 ft-lb. CPSC 16 CFR Part 1201 and the 2016 final rule; eCFR current through 23 July 2026 and verified July 25, 2026.
15. Indiana currently lists 675 IAC 13-2.6, based on the 2012 International Building Code first printing with Indiana amendments, as in effect. The rule took effect 1 December 2014; Allen County publishes the same basis. Indiana DHS and Allen County; verified July 25, 2026.

THE CHART

What are the standard glass thicknesses?

Vitro TD-120 lists 32 flat-glass reference rows from 2.0 mm to 25 mm, each with a millimetre class, a published inch range, a nominal/reference thickness and a weight. The millimetre value is a class label rather than an exact measurement, and the source warns that some listed thicknesses may not be currently available from Vitro.

Five columns describe different facts. The trade designation is the traditional inch name, when the source supplies one. The millimetre class is the printed class label. The production rangeis the source’s span of actual thicknesses. The nominal thickness is a reference used for identification and weight. The weight follows from the nominal thickness and the stated density convention.

Table 1 — Flat-glass trade thicknesses, production ranges and weights (all 32 source rows)

Source: Trade designations, millimetre classes, inch ranges, nominal inch thicknesses and lb/ft² weights are transcribed from Vitro Architectural Glass, Glass Technical Document TD-120, “Flat Glass Trade Thicknesses and Weights,” Revision 4, 28 November 2024. Millimetre columns are calculated using the exact NIST conversion of 25.4 mm per inch. The kg/m² column is calculated at the NGA convention of 2,500 kg/m³ and is therefore not a direct unit conversion of the Vitro lb/ft² column. Verified July 25, 2026.

Two details in the source table matter.

First, the source contains two rows labelled 2.0 mm — “2.0A” and “Picture” — with different ranges and nominal thicknesses. The millimetre class alone does not uniquely identify the row.

Second, five pairs share an identical nominal thickness and an identical published weight: 2.3 and 2.5 mm, 3.0 and 3.1 mm, 3.9 and 4.0 mm, 5.5 and 6.0 mm, and 9.6 and 10.0 mm. That is consistent with a trade-class system drawn across continuous production ranges rather than a list of exact measured thicknesses.

RANGES AND BOUNDARIES

Why do exact conversions, trade classes and production ranges differ?

Vitro describes float-glass manufacturing as a continuous process: the glass keeps flowing during thickness changes, and the full specified range is used as production moves from one class to another. That is why an exact mathematical conversion, a trade label, a nominal reference thickness and a production range can all be different numbers without being interchangeable.

The source’s own 6.0-to-6.2 mm example also exposes a boundary detail worth preserving. Its printed table places 0.235 inat the endpoint of both rows; the explanatory paragraph says glass is packed as 6.0 mm until the thickness exceeds 0.235 in, then says 0.235–0.243 inis packed as 6.2 mm. This page does not silently resolve that shared endpoint.

Table 3 — Vitro classes surrounding the exact 1/4-inch value

Source: Printed ranges and nominal values from Vitro TD-120 Rev. 4. Millimetre ranges are calculated using 25.4 mm per inch. The “contains” column tests the exact 0.250 in value against the printed endpoints. Verified July 25, 2026.

The exact 0.250 in value appears at the lower printed endpoint of the 6.5 mm row, not inside the 6.0 mm row. That does not rename quarter-inch glass as 6.5 mm; it demonstrates why trade nomenclature and exact measurement must remain separate fields.

PANEL WEIGHT AND NIOSH

How heavy is a full lite, and what does the 51 lb NIOSH load constant mean?

A 48 × 96 in lite in Vitro’s 1/4 in row has a nominal glass-only weight of about 93.4 lb at the 157 lb/ft³ convention. NIOSH’s Revised Lifting Equation uses a 23 kg / 51 lb load constant as the baseline under optimal conditions; the equation then reduces the recommended weight through task multipliers, so 51 lb is not a universal safe limit or a one-person permission.

Table 6 — Nominal glass-only weight by thickness and reference size

Sizes are round reference geometries chosen so the arithmetic is easy to check, not claims about typical installations.

Source: Panel weights calculated from Vitro TD-120 Rev. 4 published lb/ft² values at the 157 lb/ft³ convention. Glass only; excludes interlayers, coatings, spacers, sealants, framing and hardware. Verified July 25, 2026.

Table 7 — Area whose nominal glass-only weight equals the 51 lb NIOSH load constant

Source: 51 lb divided by the Vitro-published lb/ft² value. The 51 lb load constant comes from NIOSH Publication No. 94-110, revised September 2021, and is defined for the Revised NIOSH Lifting Equation under optimal conditions. Verified July 25, 2026.

OSHA states that it has no standard setting a universal amount a person may lift or carry and describes the NIOSH equation as voluntary guidance. Task-specific handling decisions require a full hazard and ergonomic assessment; these tables do not prescribe crew size, equipment or technique.

STRENGTH

Does thicker glass mean stronger or safer glass?

Thickness, heat-treatment classification and safety-glazing compliance are different variables. NGA publishes different bending-strength reference values for annealed, heat-strengthened and fully tempered glass, while federal safety-glazing rules classify covered products by impact and environmental performance rather than by thickness alone.

Table 8 — Published strength values at the stated reference conditions

Source: Mean and design values from National Glass Association FM05-12, “Physical and Mechanical Properties of Typical Soda Lime Float Glass,” July 2023. NGA states that these are approximate short-duration values for undamaged glass in four-sided support; the design values describe the surface, not the edge, and do not include area effects. Heat-strengthened safety status and tempered certification context are supported by Vitro TD-138 Rev. 9 and CPSC 16 CFR Part 1201. Verified July 25, 2026.

Vitro TD-138 describes heat-strengthened glass as approximately twice as strong as annealed glass of the same thickness and tempered glass as approximately four to five times as strong. The same document states that monolithic heat-strengthened glass is not a safety-glazing material and gives tempered-glass compression criteria of at least 10,000 psi surface compression or 9,700 psi edge compression, or compliance with ANSI Z97.1 or 16 CFR Part 1201.

Heat treatment does not add a separate term to the weight equation. For equal area, actual thickness and density, the reference weight remains density × thickness × area; heat treatment changes the stress state, strength classification and break behavior.

STANDARDS AND CODE

Does the building code specify one universal glass thickness?

No single universal thickness number appears across the current sources reviewed. The regulatory and standards framework divides the problem among flat-glass quality, heat treatment, load resistance, safety impact performance, manufacturer labeling and the locally adopted building code.

Table 10 — What current standards and regulations establish

Source: ASTM International active-standard pages for C1036-25, C1048-25 and E1300-24; eCFR 16 CFR Part 1201 current through 23 July 2026; CPSC final rule published 23 March 2016; and Indiana DHS current-rules page. Verified July 25, 2026.

Two distinctions are decisive. First, ASTM E1300 determines load resistance only within its stated scope and says other criteria may control final selection. Second, 16 CFR Part 1201 requires performance testing and labeling for covered products; it does not define safety glazing by a minimum millimetre or inch thickness.

SOURCE DATES

Why does this reference matter now?

Two recent primary-source updates make source dates material. Vitro revised TD-120 on 28 November 2024 and says Revision 4 included a slight adjustment to the weight-per-square-foot formula and the table weights. Any reproduction built from an earlier revision needs to be checked against the current table.

NGA then announced the updated and consolidated FB23-25 weight paper on 1 October 2025. That paper assumes 156 lb/ft³ (2,500 kg/m³) and combines the association’s earlier flat-glass and laminated-glass weight papers. This page dates and names the density behind every weight rather than silently mixing conventions.

LIMITATIONS

What are the limitations of this glass thickness chart?

The page is deliberately narrow: it is a reference for trade labels, published manufacturer ranges, conversions and calculated weights. Its limitations are stated here so a number cannot be lifted out of context and mistaken for a design, product-availability or safety determination.

• This is not a glass-design tool. It does not determine required thickness, glass type, allowable area, support conditions, edge treatment, deflection, safety classification or load resistance for an opening.
• The production ranges belong to one manufacturer document.They are the values printed in Vitro TD-120 Revision 4. They must not be generalized into guaranteed tolerances for every manufacturer, and Vitro states that some listed thicknesses may not be available from Vitro.
• The 0.235 in boundary is internally overlapping in the source.The table includes 0.235 in in both the 6.0 and 6.2 mm rows; the prose assigns 0.235 in to 6.2 mm. The dataset preserves the printed ranges and records the conflict in its notes.
• Every weight is a reference calculation, not a measurement of an individual lite. The figures describe soda-lime-silica flat glass at the density stated in the column. They exclude interlayers, coatings, ceramic frit, spacers, sealants, framing and hardware.
• Monolithic thickness and assembly thickness are different measurements.A laminated construction includes glass plies and interlayers; an insulating glass unit includes its lites and cavity or cavities. Version 1.0 does not calculate full laminated or insulating assemblies.
• No proprietary current ASTM numeric tables are reproduced. Current C1036-25, C1048-25 and E1300-24 editions and their public scope or abstract language were verified directly. Numeric dimensional-tolerance and fabrication-distance values from older editions were removed rather than carried forward without current verification.
• The 51 lb NIOSH figure is not a universal lifting limit.It is the load constant in the Revised NIOSH Lifting Equation under optimal conditions; task multipliers reduce the recommended weight, and OSHA has no universal numeric lifting standard. Table 7 is a comparison, not a handling instruction.
• The federal safety-glazing section is limited to covered products and the cited rule. Whether a specific opening is covered and what local code also requires must be determined from the applicable project documents and governing authority.
• The Indiana section is dated. It reports the state and county sources as verified on July 25, 2026. A 2026 building-code proposal is under review, but the official current-rules page still lists 675 IAC 13-2.6 as in effect and the posted proposed document still contains unfilled adoption fields.

DATASET DOWNLOAD

What files are included in the dataset download?

The download contains the same 32-row evidence block published in the HTML table, with source fields and calculations kept in separate columns. The CSV is suited to spreadsheets and data analysis; the JSON adds source metadata, formulas, rounding rules, limitations and a column dictionary.

• CSV dataset — 32 rows × 34 columns; 19.5 KB
• JSON dataset — the same 32 rows plus metadata; 61.2 KB

CSV columns:

row_id, trade_designation, common_fraction_label, mm_class, vitro_min_in, vitro_max_in, vitro_min_mm, vitro_max_mm, vitro_nominal_in, vitro_nominal_mm, vitro_weight_lb_ft2_157, weight_lb_ft2_156_nga, weight_kg_m2_2500, exact_inch_conversion_mm, mm_class_minus_exact_conversion_mm, exact_conversion_inside_vitro_range, exact_conversion_position_vs_vitro_range, distance_outside_vitro_range_mm, area_ft2_at_niosh_51lb_load_constant, panel_lb_24x36in, panel_lb_36x84in, panel_lb_48x96in, panel_lb_60x120in, base_source_primary, base_source_url, exact_conversion_source_primary, exact_conversion_source_url, density_156_source_primary, density_156_source_url, niosh_comparison_source_primary, niosh_comparison_source_url, base_source_revision_date, verified, tier

SHA-256 checksums

CSV   e26ee8bb933e87597f3c99e56c2f574f1a6e24db43c255e826aa6ed053ef0b0a
JSON  d8ffee1e442f0691bb1bf2ad885318e78422fbd364e5d43959fe60bb83db7e69

The file names, version, verification date and checksums should change only when the dataset itself changes. A layout or unrelated copy edit does not justify re-dating the evidence block.

PRIMARY SOURCES

Which primary sources support this chart?

The source register below lists only the issuing organization, original data producer, official standards publisher or government authority used for a published claim. Secondary code databases and manufacturer-document mirrors were removed from the final evidence chain.

1. Vitro Architectural Glass. Glass Technical Document TD-120: Flat Glass Trade Thicknesses and Weights, Revision 4, 28 November 2024. https://www.vitroglazings.com/media/02ubg2vz/tech_doc_120.pdf — Read and row-checked July 25, 2026. Base source for the 32 trade rows, printed ranges, nominal values, published 157 lb/ft² weights, density formula, continuous-process explanation, availability note and revision history.
2. National Institute of Standards and Technology. SI Units – Length. Updated 19 September 2025. https://www.nist.gov/pml/owm/si-units-length — Read July 25, 2026. Source for one inch being exactly 25.4 mm under the definition effective 1 July 1959.
3. ASTM International. ASTM C1036-25, Standard Specification for Flat Glass. Active page updated 19 March 2025. https://store.astm.org/c1036-25.html — Read July 25, 2026. Current-edition identity and public scope; proprietary dimensional tables are not reproduced.
4. ASTM International. ASTM C1048-25, Standard Specification for Heat-Strengthened and Fully Tempered Flat Glass. Active page updated 25 March 2025. https://store.astm.org/c1048-25.html — Read July 25, 2026. Current-edition identity and public abstract statements that fabrication occurs before heat treatment and heat-treated glass cannot be cut after tempering.
5. ASTM International. ASTM E1300-24, Standard Practice for Determining Load Resistance of Glass in Buildings. Active page updated 9 April 2024. https://store.astm.org/e1300-24.html — Read July 25, 2026. Current scope, exclusions and factors that may control final glass type and thickness selection.
6. National Glass Association. Glass Technical Paper FM05-12: Physical and Mechanical Properties of Typical Soda Lime Float Glass, July 2023. https://www.glass.org/sites/default/files/2023-07/FM05-12_2023_Physical_Mechanical_Properties_Typical_Soda_Lime_Float_Glass.pdf — Read July 25, 2026. Source for 156 lb/ft³ (2,500 kg/m³), the mean and design strength values, and their stated conditions.
7. National Glass Association. NGA Publishes Updated Glass Technical Papers, 1 October 2025. https://www.glass.org/news/2026/nga-publishes-updated-glass-technical-papers — Read July 25, 2026. Source for updated and consolidated FB23-25 and its 156 lb/ft³ (2,500 kg/m³) density assumption.
8. National Institute for Occupational Safety and Health. Applications Manual for the Revised NIOSH Lifting Equation, DHHS (NIOSH) Publication No. 94-110, revised September 2021. https://stacks.cdc.gov/view/cdc/110725 — Full official PDF read July 25, 2026. Source for the 23 kg / 51 lb load constant and its optimal-condition definition.
9. Occupational Safety and Health Administration. OSHA procedures for safe weight limits when manually lifting, 4 June 2013. https://www.osha.gov/laws-regs/standardinterpretations/2013-06-04-0 — Read July 25, 2026. Confirms that OSHA has no universal numeric lifting standard and describes the NIOSH manual as voluntary guidance.
10. U.S. Consumer Product Safety Commission. 16 CFR Part 1201, Safety Standard for Architectural Glazing Materials. https://www.ecfr.gov/current/title-16/chapter-II/subchapter-B/part-1201 — eCFR current through 23 July 2026; read July 25, 2026. Source for scope, impact and environmental requirements, labeling and effective date.
11. U.S. Consumer Product Safety Commission. Safety Standard for Architectural Glazing Materials, final rule, 81 FR 15427, 23 March 2016. https://www.federalregister.gov/documents/2016/03/23/2016-06523/safety-standard-for-architectural-glazing-materials — Read July 25, 2026. Source for Category I / Class B and Category II / Class A equivalence and the 150/400 ft-lb impact levels.
12. Vitro Architectural Glass. Glass Technical Document TD-138: Heat Treated Glass for Architectural Glazing, Revision 9, 11 September 2025. https://www.vitroglazings.com/media/acmdf3a5/tech_doc_138.pdf — Read July 25, 2026. Source for heat-strengthened and tempered strength characterizations, compression criteria and heat-strengthened safety-glazing status.
13. Vitro Architectural Glass. Glass Technical Document TD-124: Fabrication of Heat Treated Glass, Revision 1, 4 October 2016. https://www.vitroglazings.com/media/rocj2kmu/tech_doc_124.pdf — Read July 25, 2026. Source for the manufacturer’s no-further-fabrication position after heat treatment.
14. Vitro Architectural Glass. Glass Technical Document TD-140: Large Insulating Glass Units – Design Considerations, Revision 3, 26 April 2021. https://www.vitroglazings.com/media/fzzavcjr/tech_doc_140.pdf — Read July 25, 2026. Source for the standard 1 in insulating-glass example of two 1/4 in lites with a 1/2 in airspace.
15. Indiana Department of Homeland Security. Rules of the Indiana Fire Prevention and Building Safety Commission. https://www.in.gov/dhs/boards-and-commissions/fpbsc-rules/ — Read July 25, 2026. Source for 675 IAC 13-2.6, its model-code basis, effective date and currently-in-effect listing; the page itself identifies the overview as an informal navigation resource.
16. Indiana Fire Prevention and Building Safety Commission. FPBSC Meeting Materials. https://www.in.gov/dhs/boards-and-commissions/fpbsc-meeting-materials/ — Read July 25, 2026. Source showing a Building Code LSA Document listed under the 2 June 2026 meeting materials.
17. Indiana Fire Prevention and Building Safety Commission. Building Code LSA Document, file posted with the 2 June 2026 meeting materials. https://www.in.gov/dhs/files/Building-Code-LSA-Document-6.1.2026.pdf — Read July 25, 2026. Source for the proposed 675 IAC 13-2.7 / 2024 IBC basis and the still-unfilled LSA and effective-date fields.
18. Allen County, Indiana, Building Department. Building Department. https://www.allencounty.in.gov/234/Building-Department — Read July 25, 2026. Source for Allen County’s published 2012 IBC first-printing basis with Indiana amendments.
19. Allen County, Indiana, Building Department. Frequently Asked Questions – Permits & Planning. https://www.allencounty.in.gov/m/faq?cat=20 — Read July 25, 2026. Source for the county’s statement that state-level review assigns the construction design release number used at permit submission.

Fort Wayne Commercial Glass Repair Research is the independent research and reference section of FortWayneCommercialGlassRepair.com.

Last verified: July 25, 2026