how big is a3

The A3 paper size measures exactly 297 mm by 420 mm (29.7 cm by 42 cm), which is approximately 11.7 inches by 16.5 inches. This size is twice as large as A4 and half the size of A2, following the ISO 216 standard with a unique 1:√2 ratio that allows it to be easily folded into two A4 sheets. It is commonly used for small posters, diagrams, drawings, charts, brochures, and other projects requiring more visual space than A4 provides.