The A4 paper size, measuring 21 x 29.7 cm, is the most popular size in the International Standard paper size ISO 216 and is used by most countries across the globe, with the exception of the United States, Canada and some areas of Mexico. Its closest equivalents in the North American paper size series are Letter and Legal. A4 is a bit longer than the Letter, a bit shorter than the Legal, and a bit narrower than both.
Given its popularity, A4 has broad applications across various personal and professional settings. From correspondence to flyers, resumes, magazines official forms to catalogues, A4 paper can be used to create a wide variety of communication and promotional materials.
DL paper series
The DL (Dimension Lengthwise) envelope usually goes hand in hand with A4, being exactly one third of its size. Thus, DL is a common size for envelopes that can hold a sheet of A4 folded into thirds, With Compliments slips and is also used for promotional materials such as brochures, flyers, cards, and invitations.