Dimensions / Building materials / Plywood / Baltic birch plywood
Baltic birch plywood is sold as 1525 × 1525 mm (5 × 5 ft) sheets, a size Koskisen and UPM’s WISA-Birch Premium list, and as 1220 or 1250 × 2440 or 2500 mm and 1500 or 1525 mm wide panels up to 3660 mm long. Every ply is birch: Riga Ply is made of 1.45 mm veneers, so an 18 mm sheet has 13 plies at Latvijas Finieris, Metsä, UPM and Koskisen, and may measure 17.1–18.1 mm. At 680 kg/m³, 18 mm weighs 12.2 kg/m². The glue is phenolic to EN 314-2 Class 3, and faces are graded S, BB or WG; BB allows a limited number of patches.
| Square sheet (Koskisen, WISA-Birch Premium) | Plies in an 18 mm sheet; limits (Riga Ply) | Weight of 18 mm (Metsä) |
|---|---|---|
| 1525 × 1525mm5 × 5 ft | 1317.1–18.1 mm | 12.2kg/m² |
Sources: Koskisen, UPM, Latvijas Finieris. Checked October 2026.
Koskisen’s 1525 × 1525 mm, 18 mm sheet is filled in. Enter your parts, the plies you count and a measured thickness; each check follows a figure on this page.
Parts are laid out in a plain grid, all the same way round; mixing directions or nesting may fit more, and the grain direction is up to you.
A 1525 × 1525 mm sheet gives 4 parts of 720 × 560 mm with a 3 mm kerf, so 20 parts take 5 sheets. Your 5 sheets are enough.
Koskisen’s 1525 × 1525 mm sheet is filled in, with 720 × 560 mm cabinet sides and a 3 mm saw kerf as examples.
Birch plywood makers build 18 mm from 13 plies, and you count 13.
Latvijas Finieris, Metsä, UPM and Koskisen all build an 18 mm sheet from 13 plies.
Birch panels of 18 mm may be 17.1–18.1 mm; your 17.8 mm is within it.
Riga Ply 18 mm may be 17.1–18.1 mm at 9 ± 3% moisture; 17.8 mm is an example measurement.
Exporting birch plywood? Photograph a sheet and its edge, mark the size, the plies and the real thickness in SizeMarker and send it with your quote.
Mark a photoMakers’ sheets; Forest Plywood is a US distributor. Paged’s BirchPly may not be birch throughout.
| Range | Sizes | Thickness; plies | Density; grades |
|---|---|---|---|
| Koskisen birch plywoodThis page | 1525 × 1525 / 2440 / 2500 / 3050 / 3600 / 4000 mm; 1200–1250 × 2400–4000 mm | 4–50 mm; 18 mm 13 plies, 12.2 kg/m² | Birch 680 kg/m³ |
| UPM WISA-Birch PremiumSheet of 2013 | 1220 × 1220 / 2440 / 2500 / 3050, 1525 × 1525 / 2440 / 2500 / 3050 mm; ±1 mm | 18 mm 13 plies | Faces I (B) and II (S) to EN 635 |
| UPM WISA-Birch | 1220/1250 × 2440–3660, 1500/1525 × 2500–3660 mm | 6.5–50 mm; 5–37 plies | Mean density 680 kg/m³ |
| Latvijas Finieris Riga PlyLatvia | 1220/1250 or 1500/1525 × 2440–3660 mm; no square size | 4–50 mm; 3–35 plies of 1.45 mm | 670–760 kg/m³; S, BB, WG |
| Metsä Wood BirchFinland | 1200–1525 × 2400–4110 mm | 6.5–50 mm; 18 mm 13 plies, 12.2 kg/m² | 680 kg/m³; BB standard grade |
| Paged BirchPlyPoland | 1500 × 2500 / 3000 / 3300, 2500 × 1250 / 1500 mm | 4–45 mm; 35 sheets of 18 mm to a pack | 640–760 kg/m³ |
| Forest Plywood Baltic BirchDistributor, US | 5’ × 5’ (60” × 60”), 4’ × 8’, 10’ × 5’ | — | B/BB, BB/BB, BB/CP, CP/CP, C/C |
Sources: Koskisen · UPM · UPM · Hanson Plywood · UPM · Forest Plywood · Latvijas Finieris · Metsä Wood · Paged
At 9 ± 3% moisture, tolerances to EN 315. Metsä, UPM and Koskisen build the same plies up to 30 mm.
| Nominal | Plies | Lower limit | Upper limit |
|---|---|---|---|
| 4 mm | 3 | 3.5 mm | 4.1 mm |
| 6.5 mm | 5 | 6.1 mm | 6.9 mm |
| 9 mm | 7 | 8.8 mm | 9.5 mm |
| 12 mm | 9 | 11.5 mm | 12.5 mm |
| 15 mm | 11 | 14.3 mm | 15.3 mm |
| 18 mm | 13 | 17.1 mm | 18.1 mm |
| 21 mm | 15 | 20 mm | 20.9 mm |
| 24 mm | 17 | 22.9 mm | 23.7 mm |
| 30 mm | 21 | 28.7 mm | 29.9 mm |
Sources: UPM
| Item | Figure |
|---|---|
| The 1525 × 1525 mm sheetKoskisen; UPM; Latvijas Finieris; Metsä | Koskisen and WISA-Birch Premium list it; Riga Ply and Metsä list 1525 mm only with longer lengths; no maker says where the size comes from |
| Birch throughoutLatvijas Finieris; Metsä; Koskisen | Riga Ply: birch throughout, 1.45 mm veneers; Metsä: 100% birch from Finland; Koskisen’s combi panels have conifer inner plies |
| VoidsLatvijas Finieris; Forest Plywood | No maker claims void-free panels; Latvijas Finieris permits no overlaps in any grade; only distributors say “nearly void free” |
| BB gradeMetsä; Latvijas Finieris; Hanson Plywood | Metsä: wooden patches up to 3% of the area; Latvijas Finieris: up to 10 inserts per m²; Hanson: eight repairs per m² |
| GrainKoskisen | The face grain runs along the first dimension stated, for Finnish panels generally the shorter one |
| GlueLatvijas Finieris; UPM | Phenol formaldehyde to EN 314-2 Class 3, exterior; EN 636-1, -2 and -3 S in the declarations |
| Inch labelsRigaWood handbook | 18 mm is listed against 0.7188 in (23/32) and 19 mm against 0.7500 in (3/4) |
| Per palletMetsä | 1525 × 1525 or 1220 × 2440 mm at 18 mm: 50 panels |
| Weight of a square sheetOur calculation | 680 kg/m³ × 18 mm = 12.24 kg/m², printed 12.2; 1525 × 1525 mm is 2.33 m², about 28 kg |
| In the check aboveOur calculation | (1525 + 3) ÷ (720 + 3) = 2, (1525 + 3) ÷ (560 + 3) = 2: 4 parts a sheet, so 20 parts take 5 sheets; 13 plies; 17.8 mm within 17.1–18.1 mm |
Sources: Koskisen · UPM · UPM · Latvijas Finieris · Paged · Latvijas Finieris · Metsä Wood · Hanson Plywood · Forest Plywood
1525 × 1525 mm (5 × 5 ft) is the size it is known for, listed by Koskisen and WISA-Birch Premium. Mills also make 1220 or 1250 × 2440 or 2500 mm, and 1500 or 1525 mm wide panels up to 3660 mm long; Riga Ply has no square size.
13. Latvijas Finieris, Metsä, UPM and Koskisen all build 18 mm from 13 birch plies; Riga Ply’s veneers are 1.45 mm. 12 mm has 9 plies and 24 mm 17.
Not quite: Latvijas Finieris lists 18 mm against 0.7188 in (23/32) and 19 mm against 0.7500 in (3/4). A Riga Ply 18 mm sheet may be 17.1–18.1 mm.
No maker says so. Latvijas Finieris permits no overlaps in any grade and Metsä patches its BB faces; “nearly void free” is a distributor’s phrase.
About 12.2 kg/m² at 18 mm (Metsä, 680 kg/m³), so a 1525 × 1525 mm sheet is about 28 kg.
Buyers ask for the size and which way the face grain runs, the nominal and real thickness, the number of plies and whether the core is all birch, the face and back grades and how many patches they allow, the glue and bond class, the formaldehyde class, and sheets and weight per pallet. Mark the real sheet and its edge on your own photo in SizeMarker, as in the picture at the top, and send one product card for WhatsApp or WeChat.
