A mirror with an integrated hanging mechanism. Drilled hole. Very minimalist. What size is it?

The A4 format (often also called DIN A4) is the most common format worldwide and one of the formats for writing paper standardized in DIN standard "DIN 476" and in ISO standard "DIN EN ISO 216".

A4 is 210 mm x 297 mm in size.

A nail is included with the mirror.
A lot of text for such a concise article.

Design: Theo van Egmond, 1996 (2019)
Dimensions: approx. W 21 x H 29.7 cm (A4)
with beveled polished edge / glass thickness 5 mm