Plywood Thickness: Different Types & Sizes In MM & Inches
On this page 6 sections
Key takeaways
- Indian plywood is sold in metric thicknesses: 6 mm is about 1/4 inch, 12 mm about 1/2 inch, 18–19 mm about 3/4 inch and 25 mm about 1 inch.
- Use 18–19 mm plywood for wardrobe, bed, shelf and kitchen carcasses and other parts that carry weight, and 6 mm for backs and drawer bottoms.
- 12 mm plywood suits light partitions and wall panels, while subfloors under tiles need at least 15–16 mm, with 18–19 mm preferred.
- Thickness decides strength and the grade decides water resistance, so wet areas need BWP or marine plywood whatever the thickness.
- Thicker is not automatically better: where a part carries no load, extra thickness only adds weight, bulk and cost.
Use 18–19 mm (3/4″) plywood for anything that carries weight, such as wardrobe, bed, shelf and kitchen carcasses, tables and desks. Use 12 mm (1/2″) for light partitions and wall panels, 6 mm (1/4″) for backs and drawer bottoms, 4 mm for curved and decorative work, and 25 mm (1″) for heavy-duty and structural work.
Plywood thickness chart in mm and inches
Indian plywood is made and sold in metric thicknesses. The inch figures below are the nearest imperial sizes, so a "half-inch" sheet in India is a 12 mm sheet and a "three-quarter-inch" sheet is 18 or 19 mm.
| Thickness (mm) | Nearest inch size | Typical uses |
|---|---|---|
| 4 mm | 5/32″ (just over 1/8″) | Curved work, craft projects, light decorative panels |
| 6 mm | 1/4″ | Wardrobe and cabinet backs, drawer bottoms |
| 9 mm | 3/8″ | Wall panelling and light cladding that carries no load |
| 12 mm | 1/2″ | Light partitions, wall panels, headboards, small shutters |
| 15–16 mm | 5/8″ | Subfloors under tiles (minimum), exterior wall sheathing |
| 18–19 mm | 3/4″ | Wardrobe, bed, shelf and kitchen carcasses; shutters; tables and desks; subfloors |
| 25 mm | 1″ | Heavy-duty tops, structural and industrial use |
MRS Woodcraft makes plywood in thicknesses from 4 mm to 25 mm, in 8 × 4, 7 × 4 and 7 × 3 ft sheets. If you are also planning how to cut your sheets, see our guide to standard plywood sheet sizes.
Which plywood thickness to use for common projects
For most furniture the rule is simple: 18–19 mm for the parts that carry weight, 6 mm for backs and drawer bottoms, and 12 mm for light panels. The notes below cover each project in a little more detail.
Plywood thickness for wardrobes
Use 18–19 mm for the wardrobe carcass (sides, top, bottom and shelves) and 6 mm for the back panel. Shutters are usually 18–19 mm as well; 12 mm can be used for small, light shutters. BWR plywood is the usual grade for wardrobes, and our guide to plywood for wardrobes covers the choice in detail.
Plywood thickness for beds
Use 18–19 mm (3/4″) for the bed frame, slats or platform and any storage box, because these parts carry the mattress and the people on it. Parts that carry little weight, such as the headboard, can be 12 mm (1/2″).
Plywood thickness for kitchen cabinets
Use 18–19 mm for the cabinet carcasses and 6 mm for backs and drawer bottoms. In a kitchen the grade matters as much as the thickness: use BWP or marine plywood for sink and hob units and BWR for units away from water. Read more in our guide to the best plywood for kitchens.
Plywood thickness for tables and desks
Use 3/4″ (18–19 mm) plywood for tabletops, desktops and frames so they support the weight placed on them without bending. Drawer bottoms and decorative panels can be 1/4″ (6 mm).
Plywood thickness for walls and partitions
12 mm (1/2″) is the usual thickness for plywood wall panels and light partitions; it is stiff enough without being bulky. For exterior wall sheathing, where strength matters more, use 15–16 mm (5/8″) in a BWP or marine grade.
Plywood thickness for subflooring
Under tiled floors, use plywood at least 15–16 mm (5/8″) thick; 18–19 mm (3/4″) is preferred because it is sturdier and flexes less under load.
How thickness affects strength, weight and cost
Thickness decides how much load a panel can carry and how much it bends. Too thin, and shelves sag or the structure feels weak; too thick, and the piece is heavier, bulkier and costlier than it needs to be.
- Strength and stability: thicker plywood handles heavier loads and stays flatter over a span.
- Flexibility: thin plywood bends more easily, which suits curved surfaces and intricate designs.
- Insulation and sound: thicker plywood gives somewhat better insulation and sound absorption.
- Weight and cost: every extra millimetre adds weight and material, so match the thickness to the load rather than going thicker everywhere.
Thickness and grade are separate choices
Thickness decides strength; the grade decides how well the plywood copes with moisture. You need to get both right, because a thick sheet of the wrong grade will still fail near water.
| Grade | Where to use it |
|---|---|
| MR / commercial | Dry interiors |
| BWR (boiling water resistant) | Wardrobes, beds and kitchen units away from water |
| BWP (boiling waterproof) or marine | Kitchen sink and hob units, bathroom vanities, utility areas, exteriors |
General-purpose MR, BWR and BWP plywood is covered by the Indian Standard IS 303, and marine plywood by IS 710. Softwood, hardwood and marine plywood are all commonly made in 6, 12 and 19 mm. For the difference between the two water-resistant grades, see BWR vs BWP plywood.
Common mistakes when choosing plywood thickness
The most common mistakes are going thicker everywhere, assuming all plywood of one thickness performs the same, and swapping thicknesses partway through a job.
- Thicker is always better: thicker plywood is stronger, but using it for light or decorative parts only adds bulk, weight and cost.
- All plywood of the same thickness is the same: the wood species, the glue and the number of plies change how a sheet performs, even at the same thickness.
- Substituting thicknesses freely: dropping from 18–19 mm to 12 mm on a load-bearing part weakens it, and mixing thicknesses in one piece makes joints and hardware harder to line up.
To see the grades, thicknesses and sheet sizes MRS Woodcraft makes, visit our plywood page or ask us for a quote.
Frequently Asked Questions
Can plywood thickness vary between manufacturers?
Yes, slightly. A sheet sold as 18 mm or 19 mm can measure a little under or over its nominal size, and a poorly made sheet may not be the same thickness all over. Measure a few sheets at several points before you buy; our guide on how to check plywood quality explains what else to look for.
Should I use 18 mm or 19 mm plywood for furniture?
Both are sold as 3/4-inch plywood and both are used for wardrobe, bed and kitchen carcasses. The difference is about a millimetre, so the grade and build quality matter more. Whichever you choose, use the same thickness throughout one piece of furniture so that joints, edge banding and hardware line up.
