The best flyer size is around 8.5 x 11 inches in the US, which is very similar to A4 paper size (21 × 29.7 cm) for the rest of the world. It’s perfect if you’re printing flyers to use as signs on bulletin boards, utility poles, centers, or entry ways. Smaller sizes are also quite popular, specifically the A5 paper size (14.8 × 21 cm), but the A4 paper size is made to truly get noticed.