EN 13986 → EN 315
Thickness · EN 315
Allowed 17.06–18.74 mm
+(0.2 + 0.03×t) / −(0.4 + 0.03×t)
+0.74 / −0.94 mm · sanded
Within-panel ≤ 0.6 mm
Tools/Thickness & dimensions
Thickness & dimensions referencer
Look up mm ↔ inch and US trade thicknesses, screen a measured panel against EN 315 / EN 13986 or PS 1 bands, and read panel-size nicknames without confusing Euro sheets for US 4×8. Cross-check durability and emission families in the standards matrix.
Thickness, tolerances & panel sizes
Convert mill millimetres to US colloquial thickness, then look up EN 315 (via EN 13986) and PS 1 dimensional rules for a stated thickness × width × length — no measured fields, rules only.
18 mm ≈ 3/4" US trade (23/32" exact). Face 1220×2440 mm — “4×8” (metric).
US / APA Performance Category
Thickness · PS 1
Treating 18 mm as Perf Cat 0.7087″
Allowed 17.6–18.4 mm
±1/64″ (Perf Cat ≤ 3/4)
±0.4 mm · sanded
EN 315 · ±3.5 mm
Width
Nominal 1220 mm → 1216.5–1223.5 mm
EN 315 · ±3.5 mm
Length
Nominal 2440 mm → 2436.5–2443.5 mm
√(W² + L²)
Diagonal
Nominal 2728 mm
Envelope from ±3.5 mm on W & L: 2723.31–2732.7 mm
EN 315 · 1 mm/m
Squareness
Max |d1 − d2| ≤ 2.44 mm
Based on longer side 2440 mm · measure both diagonals per EN 324-2
Edge straightness: also 1 mm/m
- · Reference moisture for EN 315: about 10% (±2%). Measure per EN 324.
- · Length and width (on nominal): ±3.5 mm.
- · Face diagonal: √(W²+L²); allowed envelope follows ±3.5 mm on both edges.
- · Squareness (and edge straightness): 1 mm per metre — typically |d1 − d2| ≤ 1 mm/m × longer side.
- · Thickness on nominal depends on sanded vs unsanded — see checker formulas.
- · Within-panel thickness variation is a separate EN 315 limit (band by thickness class).
Planning / literacy tool only. EN 13986 points to EN 315 for dimensional tolerances at ~10% MC (±2%). US figures follow PS 1 Performance Category thickness rules as summarised by APA / TPC guidance. Mill contracts, CE DoPs, APA stamps, and the buyer’s written QC plan always win. This is not a certification or acceptance certificate.
Frequently asked
Is 18 mm the same as 3/4 inch plywood?
As a US trade nickname, export 18 mm is often sold as “3/4”, but exact conversion is ≈0.709″ (nearest fraction 23/32″). True 3/4″ is 19.05 mm — domestic North American stock is often closer to 19 mm. Always put millimetres (or a PS 1 Performance Category) on the PO.
What does EN 13986 have to do with thickness tolerance?
EN 13986 is the construction wood-based panels umbrella. For plywood dimensional tolerances it points to EN 315 (thickness, length/width, squareness, edge straightness), with measurements per EN 324. This tool applies the widely published EN 315 sanded/unsanded thickness formulas for literacy — confirm the edition on your CE file.
Are 1220×2440 and 1250×2500 both “4×8”?
Only as informal nicknames. 1220×2440 is the global export “4×8”. 1250×2500 is the Euro sheet — larger on both sides. True 4′×8′ is 1219.2×2438.4 mm. Do not assume they fit the same CNC nest or wall bay.
What is a PS 1 Performance Category?
On APA / PS 1 stamps, PERF CAT (e.g. 15/32 CAT, 3/4 CAT) is the thickness designation tied to building-code span tables. The stamp also shows a measured thickness in thousandths of an inch. Tolerances depend on sanded vs unsanded and whether the category is above or below the 3/4 or 13/16 thresholds.
Can I use this checker to reject a shipment?
No. Use it to understand the bands and prepare questions. Contractual acceptance needs the mill’s stated standard, sampling plan, calibrated gauges, moisture condition, and written QC agreement.
Standards notes & sources
Planning / literacy tool only. EN 13986 points to EN 315 for dimensional tolerances at ~10% MC (±2%). US figures follow PS 1 Performance Category thickness rules as summarised by APA / TPC guidance. Mill contracts, CE DoPs, APA stamps, and the buyer’s written QC plan always win. This is not a certification or acceptance certificate.
EN 13986
Wood-based panels for use in construction — references EN 315 for plywood dimensional tolerances.
Reference ↗EN 315
Plywood — tolerances for dimensions (thickness, length/width, squareness, edge straightness).
Reference ↗EN 324-1 / EN 324-2
Measurement methods for thickness, length/width, squareness, and edge straightness.
Reference ↗US PS 1 (APA)
Structural plywood — Performance Category thickness labelling and finish-dependent tolerances.
Reference ↗