Acrylic (PMMA) and polycarbonate sheet thickness: nominal vs actual, 1/8 in = 3 mm, 1/4 in = 5.5 mm, inch and mm (two acrylic tables, three polycarbonate listings) — dimension sheet Source: Xem Studio, https://xemstudio.com/objects/acrylic-and-polycarbonate-sheet-thickness/ (sheet CC BY 4.0) Basis: Acme Plastics and A&C Plastics acrylic thickness tables compared row by row; Lexan 9034 listings from Aircraft Spruce, K-Mac and U.S. Plastic Catalog version: 2026-10-20 Sizes: see table below - Acrylic (PMMA) sheet sold in inch sizes is often not the inch thickness on the label: a '1/4 in' cast acrylic sheet is 5.5 mm (0.217 to 0.220 in) because cast sheet is made in metric steps; the A&C chart also lists a 6 mm / 0.236 in sheet under 1/4 in. Acme prints the thickness tolerance as ±10 % (often under 5 %), which can vary across a sheet, so design slots and pockets with the real sheet in hand. - Where the two acrylic tables disagree: 1/4 in is .217 (Acme) vs .220 (A&C), and 3/4 in is .709 vs .708, 1 in is .945 vs .944. Those are rounding of the same 5.5, 18 and 24 mm values (5.5 mm = 0.2165 in, 18 mm = 0.7087 in, 24 mm = 0.9449 in), shown as printed. Acme also lists 0.06 / 0.08 / 0.09 / 0.098 in nominal sheets at 1.5 / 2 / 2.3 / 2.5 mm, without inch values. - Polycarbonate: three distributors list Lexan 9034 in inch nominal thicknesses (.060, .062, .093, .094, .118, .125, .188, .250, .375, plus .220 and .472 at U.S. Plastic with mm 5.5 and 12.7 printed in the product title). Unlike acrylic, the thicknesses .125, .250 and .375 are listed as such, but no distributor's tolerance statement was read, so none is claimed; polycarbonate is also sold in metric thicknesses by other makers (not read). - No STEP/STL: a sheet is a plain box. Left out: sheet widths and lengths (distributors list many; 4 × 8 ft and 48 × 96 in appear in the sources), extruded sheet (thinner tolerance differs), nylon, HDPE, UHMW, PTFE and acetal sheet (no table read). sheet and nominal thickness actual mm actual inch, Acme actual inch, A&C / PC distributors source acrylic, 0.06 in 1.5 — — Acme acrylic, 0.08 in 2 — — Acme acrylic, 0.09 in 2.3 — — Acme acrylic, 0.098 in 2.5 — — Acme acrylic, 1/8 in 3 .118 .118 Acme and A&C acrylic, 3/16 in 4.5 .177 .177 Acme and A&C acrylic, 1/4 in 5.5 .217 .220 Acme and A&C acrylic, 1/4 in (6 mm) 6 — .236 A&C acrylic, 3/8 in 9 .354 .354 Acme and A&C acrylic, 1/2 in 12 .472 .472 Acme and A&C acrylic, 3/4 in 18 .709 .708 Acme and A&C acrylic, 1 in 24 .945 .944 Acme and A&C acrylic, 1-1/4 in 30 1.18 — Acme acrylic, 1-1/2 in 38 1.50 — Acme acrylic, 2 in 50 1.97 — Acme acrylic, 2-1/2 in 60 2.36 — Acme acrylic, 3 in 75 2.95 — Acme polycarbonate (Lexan 9034), 0.060 in — — 0.060 Aircraft Spruce polycarbonate (Lexan 9034), 0.062 in — — 0.062 K-Mac polycarbonate (Lexan 9034), 0.093 in 2.4 (U.S. Plastic title) — 0.093 U.S. Plastic; Aircraft Spruce polycarbonate (Lexan 9034), 0.094 in — — 0.094 K-Mac polycarbonate (Lexan 9034), 0.118 in — — 0.118 Aircraft Spruce polycarbonate (Lexan 9034), 0.125 in — — 0.125 K-Mac polycarbonate (Lexan 9034), 0.188 in — — 0.188 K-Mac polycarbonate (Lexan 9034), 0.220 in 5.5 (U.S. Plastic title) — 0.220 U.S. Plastic polycarbonate (Lexan 9034), 0.250 in — — 0.250 K-Mac polycarbonate (Lexan 9034), 0.375 in — — 0.375 K-Mac polycarbonate (Lexan 9034), 0.472 in 12.7 (U.S. Plastic title) — 0.472 U.S. Plastic Files elsewhere (not hosted by Xem Studio; license as stated by the publisher): - Acme Plastics: Acrylic sheet thickness: nominal vs actual mm and inch (tolerance +/- 10%, often under 5%) — web — Publisher's page; dimensions are facts — https://www.acmeplastics.com/acrylic-sheets/acrylic-cast-clear-sheet - A&C Plastics: Thickness conversion chart: nominal, decimal inch and mm for acrylic sheet — web — Publisher's page; dimensions are facts — https://www.acplasticsinc.com/pages/thicknessconversioncharts - Aircraft Spruce: Lexan polycarbonate sheet thicknesses .060, .093, .118 in — web — Publisher's page; dimensions are facts — https://www.aircraftspruce.com/catalog/mepages/2024_leadedge.php - K-Mac Plastics: Lexan 9034 sheet thicknesses .062, .094, .125, .188, .250, .375 in (48 x 96 in) — web — Publisher's page; dimensions are facts — https://kmac-distribution.com/plastics/lexan-9034-sheets.htm - U.S. Plastic Corp: Clear LEXAN 9034 polycarbonate sheet: 0.093 in (2.4 mm), 0.220 in (5.5 mm), 0.472 in (12.7 mm) — web — Publisher's page; dimensions are facts — https://www.usplastic.com/catalog/item.aspx?itemid=28089 No true-size file yet: the published figures do not fix the whole shape; a measured scan is planned. API: https://xemstudio.com/api/geometry?object=acrylic-and-polycarbonate-sheet-thickness