Most of us are familiar with an A4 sheet of paper, but it can be harder visualising how large an A1 poster will look or how an A6 postcard might fit into your hand.
Here’s a handy collection of all the ‘A’ paper sizes together measured in mm, as well as a standard business card.
And just to give it some scale – here are A3 to AO posters next to a silhouette (in this case me!).
For more info check out my blog on visualising even larger format displays here.