6 mm = 0.23622 in; 9 mm = 0.35433 in; 12 mm = 0.47244 in; 15 mm = 0.59055 in; and 20 mm = 0.78740 in. These are the decimal-inch equivalents of the five nominal metric thicknesses.
For a quick ruler comparison, the nearest 1/64-inch marks appear below. Keep the millimeter thickness on a slab drawing or purchase order: the fraction is an approximation, not another product size.
6, 9, 12, 15 and 20 mm to inches
These enlarged technical cross-sections show a short cut edge, not the proportions of an entire slab. Each uses the same 5 mm grid, so their heights are comparable. The inch decimals are rounded to five places; the fractions are rounded to the nearest 1/64 inch.
On a phone, swipe the table sideways. Tap a cross-section to enlarge it.
| Nominal thickness | Decimal inches | Nearest 1/64 in | Familiar reference |
|---|---|---|---|
 6 mm
|
0.23622 in | ≈ 15/64 in | Just under 1/4 in |
 9 mm
|
0.35433 in | ≈ 23/64 in | Just under 3/8 in |
 12 mm
|
0.47244 in | ≈ 15/32 in | Under 1/2 in |
 15 mm
|
0.59055 in | ≈ 19/32 in | Under 5/8 in |
 20 mm
|
0.78740 in | ≈ 25/32 in | Over 3/4 in |
Why 12 mm is not exactly 1/2 inch
A true half inch is 12.7 mm, so it is 0.7 mm thicker than a nominal 12 mm slab. Likewise, 3/4 inch is 19.05 mm, which is 0.95 mm thinner than 20 mm. Those familiar fraction names are useful conversational shortcuts, but replacing a metric size with them changes the number.
“12 mm” and “1/2 in” are different dimensions. If one appears on a drawing and the other on a quotation, confirm which size is intended before fabrication.
The comparisons below use one scale for each pair. The green bar is the metric size; the dark bar is the familiar inch fraction. Their ends do not meet, even though the everyday names sound equivalent.
Convert another millimeter value
The inch is defined as exactly 25.4 mm. For example, 18 ÷ 25.4 = 0.70866 in when rounded to five decimal places. To go the other way, multiply inches by 25.4. Round only for display; keep the original metric designation in the product specification.
Material thickness versus finished assembly depth
The chart converts the slab itself, measured between its two broad faces. It does not include adhesive, backing, a support frame, or a constructed front edge. A wall facing relies on its specified backing and fixing system; a countertop needs its own support plan even when the visible stone edge looks substantial.
Funtek's quality and inspection standard specifies a thickness tolerance of ±0.3 mm from the nominal slab value. Thus an accepted nominal 12 mm slab can measure 11.7–12.3 mm; the nominal size is still 12 mm, and it is still distinct from 12.7 mm. Use the selected product's specification and the approved drawing to control the order.
A photograph of a sample face or finished wall cannot establish material thickness. For a loose sample, check an accessible straight edge with a suitable caliper and compare the result with its product specification; avoid reading from a bevel or built-up edge.
Use the metric size when selecting a Funtek slab
In Funtek's technical data sheet, standard printed-body slab production includes 6, 9, 12 and 15 mm. The 20 mm option is confirmed by project rather than assumed available in every design and finish. The suitable thickness also depends on the application and support: a thin wall or furniture facing has a different job from a countertop or large island.
- 6 or 9 mm: confirm the intended facing application and its backing or support; do not specify from thickness alone.
- 12 or 15 mm: compare the countertop, island or furniture design with its support and finished edge.
- 20 mm: confirm the selected design, format, processing and production terms for the project.
The countertop thickness and support guide covers the choice among worktop configurations. The conversion table here remains the quick reference for translating those metric sizes.
On a drawing or enquiry, write the nominal mm thickness first, then add the inch conversion in parentheses if it helps another team read the dimension. Include the application, intended panel size and any required finished edge separately. This keeps material thickness and assembly depth from being confused.
Specify “nominal 12 mm slab (0.47244 in reference)” instead of substituting “1/2 in slab.”
Match a slab thickness to your project
Send your application, nominal thickness, approximate panel size and quantity. Funtek can share relevant slab options, sample information and quotation details; add the destination if you know it.