Berta Store · Material Guide
Baltic Birch plywood often uses metric thickness specifications. The familiar 3/4″ and 1/2″ labels commonly correspond to 18mm and 12mm panels, not exact inch measurements. Use the chart to compare sizes, then measure the actual sheet before cutting dados, grooves, or other fitted joints.
Baltic Birch Thickness Chart: Millimeters & Inches
Compare metric sizes with familiar U.S. thickness labels. Converted inches are mathematical values—not measurements of a delivered panel.
| Metric size | U.S. label / comparison | Converted inches |
|---|---|---|
| 3mm | 1/8″ class | 0.1181″ |
| 5mm | 3/16″ class | 0.1969″ |
| 6mm | 1/4″ class | 0.2362″ |
| 9mm | 3/8″ class | 0.3543″ |
| 12mm | 1/2″ class | 0.4724″ |
| 15mm | 5/8″ class | 0.5906″ |
| 18mm | 3/4″ class | 0.7087″ |
| 21mm | Approximately 13/16″Not a full 1″ panel | 0.8268″ |
How to read the chart: “Class” describes a trade label, not exact equality. Convert millimeters to inches by dividing by 25.4; values here are rounded to four decimal places. Some mills specify 6.5mm rather than 6mm, and metric sizes also have manufacturing tolerances. Always check the specification for the exact panel. For thin panels, compare 3/16-inch plywood and nearby metric thicknesses before specifying a back or insert.
Nominal vs. Metric vs. Actual Thickness
The number used to shop for plywood is not necessarily the number to use for a precision joint. Keep these three measurements separate.
18mm vs. 3/4″
18mm ≈ 0.7087″A true 3/4″ equals 19.05mm. That is 1.05mm thicker than 18mm, so a groove cut for a full 3/4″ can leave an 18mm panel loose.
12mm vs. 1/2″
12mm ≈ 0.4724″A true 1/2″ equals 12.7mm. Check the delivered panel instead of assuming a nominal half-inch cutter will produce the fit your design needs.
6mm vs. 1/4″
6mm ≈ 0.2362″A true 1/4″ equals 6.35mm. A quarter-inch trade label does not tell you whether the actual product is specified as 6mm, 6.5mm, or another value.
5mm vs. 3/16″
5mm ≈ 0.1969″A true 3/16″ equals 4.7625mm. This makes 5mm slightly thicker than the exact inch fraction: nominal plywood is not always thinner than its label.
Comparing other plywood types? See our general plywood thickness chart, then confirm the specification of the product you plan to order.
Thicker-panel reference
Is 21mm Baltic Birch 13/16″ or 1″?
21mm is approximately 13/16″—not a full 1″. An exact 13/16″ equals 20.6375mm, about 0.36mm less than 21mm. A full inch is 25.4mm, which is 4.4mm more than 21mm.
Use 21mm (approximately 13/16″) for clarity. Keep the metric specification when checking your drawing, hardware, and joinery rather than treating the inch comparison as an exact substitute.
This is a size reference, not a stock announcement. Confirm the product’s grade, sheet dimensions, thickness specification, and ordering availability before purchasing.
13/16″ = 20.6375mm
1″ = 25.4mm
Use the metric specification.
Choose by application
Which Baltic Birch Thickness Fits Your Project?
Start with the component you are building, then check its span, load, supports, joints, and hardware requirements. These are selection starting points—not load ratings or universal construction rules.
Cabinet boxes & furniture panels
18mm / 3/4″-class Baltic Birch is a starting point for cabinet sides, tops, bottoms, and furniture panels. Follow the project drawing and select the face grade for the surfaces that will remain visible.
Drawer boxes
12mm / 1/2″-class material is an option where the design allows it. Check your slide manufacturer’s permitted side thickness, clearances, bottom position, and notching instructions before cutting.
Backs & drawer bottoms
Thin panels such as 5mm or 6mm may suit supported backs or bottoms. Select around the panel size, expected contents, groove fit, and support—not a rule that every drawer uses the same bottom.
Shelves & wider spans
Thickness alone does not establish shelf capacity. Review the load, support spacing, and construction details. A thicker sheet does not remove the need for suitable supports.
Plan before ordering: use the plywood thickness calculator for preliminary comparisons. Check its assumptions against your project; it is not a certified load rating for an individual sheet.
Explore Baltic Birch at Berta Store
Choose the Right Grade & Finish
Once the thickness is right, choose the surface for your project. BB/BB and B/BB describe face grades; a clear or white factory-finished surface is a separate choice. Check each product page for its offered thicknesses and ordering details.
UNFINISHED · BB/BB
BB/BB Baltic Birch Plywood
Two sanded, unfinished BB-grade faces, with small, sound patches permitted. Compare this option when you plan to paint, stain, or clear-finish your project.
For projects where small face patches are acceptable.
View BB/BB Plywood
UNFINISHED · B/BB
B/BB Baltic Birch Plywood
A cleaner B-grade front face with a BB-grade back that may contain sound patches. Choose the face quality around the parts of your project that will remain visible.
For a cleaner natural-birch show face.
View B/BB Plywood
PREFINISHED · NATURAL BIRCH
Prefinished Baltic Birch Plywood
Natural birch grain with a factory-applied transparent protective surface on both sides. Compare it for cabinet interiors, shelves, and visible furniture components.
For a natural birch look with prefinished faces.
View Prefinished Baltic Birch
PREFINISHED · WHITE MELAMINE
White Melamine Baltic Birch
A factory-applied white melamine surface on both sides over a Baltic Birch core. Compare it for cabinet interiors, closet systems, shelving, and storage projects.
For a finished white surface without painting.
View White Melamine Baltic BirchCompare the complete Baltic Birch range.
Browse unfinished and prefinished options together, then check the exact product specification before ordering.
Baltic Birch Sheet Sizes: 4×8 vs. 5×5
Sheet size describes the panel’s length and width; thickness describes its depth. A 4×8 format covers 32 square feet, while a 5×5 format covers 25 square feet. Your cut layout can make one format more efficient than the other.
Berta’s BB/BB and B/BB listings use a 4×8 sheet format. Do not assume every Baltic Birch finish uses the same footprint or that 5×5 sheets are offered. Confirm the supplier’s exact dimensions and usable cutting area, especially for surface-finished panels.
Read the plywood sheet size guide for format comparisons, and use the plywood sheet calculator to plan quantities.
How Thickness Affects Fit & Performance
Rigidity, handling, and joinery all matter. For otherwise comparable panels, more thickness generally means greater stiffness and weight. But a thickness label alone does not establish a safe span, a screw specification, or a precise groove width.
- Measure the panel.Check several points with a suitable caliper or micrometer. Do not size precision joinery from the nominal label alone.
- Confirm the tolerance.Ask for the tolerance of the exact product. Do not apply another manufacturer’s tolerance to a different panel.
- Make a test joint.Route or cut an offcut first. Confirm the fit before machining the full batch of cabinet or furniture parts.
- Check the complete design.Review span, load, supports, fasteners, and hardware. Plan safe handling for the size and weight of the sheet.
Common questions
Baltic Birch Thickness FAQs
Is 3/4″ Baltic Birch actually 3/4″ thick?
Not necessarily. Berta’s BB/BB 3/4″ option is specified as 18mm, which converts to about 0.7087″. A true 3/4″ is 19.05mm. Measure the delivered panel rather than treating either the nominal label or the conversion as an actual measurement.
What thicknesses does Baltic Birch plywood come in?
The reference chart covers 3mm, 5mm, 6mm, 9mm, 12mm, 15mm, 18mm, and 21mm comparisons. Mill assortments vary and may include 6.5mm or other sizes. This is not a universal stock list; check the particular product and supplier.
Are 3/16″ and 1/4″ Baltic Birch interchangeable?
No. The 5mm and 6mm reference sizes differ by 1mm, and their exact inch labels differ too. That can change groove fit and the suitability of the panel for a supported back or drawer bottom. Check the drawing and the product’s stated thickness.
Why do Baltic Birch listings show both inches and millimeters?
A supplier may use a metric specification for the panel and an inch-based trade label familiar to U.S. buyers. Showing both helps with shopping, but precision work should use the actual measured thickness and the exact product specification.
What Baltic Birch thickness should I choose for cabinets?
18mm / 3/4″-class panels are a starting point for cabinet boxes and furniture components. Drawer parts and supported backs may use thinner material. The appropriate choice depends on your drawing, dimensions, load, joints, supports, and hardware.
Can I use 21mm plywood where a drawing calls for 1″?
Do not treat them as equivalent. A full inch equals 25.4mm, so 21mm is 4.4mm thinner. Confirm any substitution with the project designer and check all affected joints and hardware.
Does a factory finish change the thickness I should measure?
For fitted joints, measure the finished panel as it will be used. Confirm whether the supplier’s stated thickness includes the surface treatment; do not assume that different finishes with the same nominal label have identical measured thickness.
Is every thickness in this chart sold by Berta Store?
No. The chart is a reference, not an availability list. Check each product page for the offered thicknesses, finish, sheet dimensions, and current ordering status. A 21mm reference does not mean a 21mm product is available to order.
From Thickness Selection to Your Cut List
Once you have checked the thickness and finish, plan the sheet format and quantity around your actual parts.
The right sequence: choose the thickness for the design, verify the product’s specification, select the face grade and finish, then measure the delivered panel before machining. That keeps the shopping label from becoming a joinery mistake.
