Some of the most commonly asked questions about paper sizes are asked about those paper sizes that are, or were, most often used in the office environment. These are the A4 paper size used internationally, Letter and Legal paper sizes in the US and the old imperial foolscap paper size that was used in the British Commonwealth prior to the introduction of the ISO 216 standard.

Letter at 279mm (11.0") is slightly smaller than A4 at 297mm (11.7"), both Legal at 356mm (14.0") and Foolscap at 330mm (13.0") are longer than A4 with Legal being the longest. Foolscap is the narrowest at 203mm (8.0"), followed by A4 at 210mm (8.3") and then Letter and Legal at 216mm (8.5").

The following comparison table gives the sizes in millimeters and inches of A4, Letter, Legal and Foolscap Folio paper together with the areas and aspect ratios for these types of paper.

Size	Width x Height (mm)	Width x Height (in)	Area sq m	Area sq yd	Aspect Ratio
A4	210 x 297 mm	8.3 x 11.7 in	0.062 sq m	0.074 sq yd	1:1.4142
Letter	216 x 279 mm	8.5 x 11.0 in	0.060 sq m	0.072 sq yd	1:1.2941
Legal	216 x 356 mm	8.5 x 14.0 in	0.077 sq m	0.092 sq yd	1:1.6471
Foolscap	203 x 330 mm	8.0 x 13.0 in	0.067 sq m	0.080 sq yd	1:1.625

What Is The Difference Between A4 And Letter Paper Sizes?

The international A4 paper size is 6mm (0.2") narrower and 18mm (0.7") longer than the US Letter paper size. Overall the area of the A4 is slightly bigger than that of Letter by 0.002 square metres (approx 0.002 square yards).

What Is The Difference Between A4 And Legal Paper Sizes?

As with the Letter paper size A4 size paper is 6mm (0.2") narrow than US Legal paper, however unlike previously A4 has a smaller length than Legal paper by 59mm (2.3"). Thus Legal paper is bigger in area than A4 by 0.015 square metres (0.18 square yards).

What Is The Difference Between A4 And Foolscap Paper Sizes?

The old UK imperial Foolscap Folio paper is 7mm (0.3") narrower than A4 and 33mm (1.3") longer than A4. Its overall area is 0.005 square metres (approx 0.006 square yards) bigger than the current international A4 standard paper size. Foolscap Folio is no longer in everyday use and you are most likely to come across it if you are looking through old records.

What Is The Difference Between Legal And Letter Paper Sizes?

US Letter and Legal paper both have the same width at 8.5" (216mm) with the Legal paper size being 3" (77mm) longer than the Letter paper size. Nowadays with the proliferation of cheap printers Legal paper is becoming less common as the cost of having two paper trays in a printer is significantly greater than just having one and Letter size paper is winning out when printers only have a single tray. The difference in area is 0.020 sq yd (0.017 sq m) with the longer Legal paper being the bigger of the two.

What Is The Difference Between Letter And Foolscap Paper Sizes?

The Letter paper size is 0.5" (13mm) wider than the Foolscap paper size and Foolscap is 2.0" (51mm) longer than Letter. The difference in overall area is 0.008 sq yd (approx 0.007 sq m) with Foolscap being the larger.

What Is The Difference Between Legal And Foolscap Paper Sizes?

The Legal paper size is 0.5" (13mm) wider than the Foolscap paper size and 1.0" (25mm) longer. The difference in overall area is 0.012 sq yd (approx 0.010 sq m) with Legal paper being bigger.