Paper Sizes Explained

Six paper sizes drawn nested and to scale from a shared bottom-left corner: A3, Tabloid, Legal, A4, Letter and A5, with each outline labelled and its millimetre dimensions listed alongside.
Every common size drawn to scale from one corner. Letter is wider than A4 but shorter, which is the whole of the A4 versus Letter problem in one picture.

Complete guide to understanding paper sizes: US formats, ISO standards, and choosing the right size for your graph paper

Overview of Paper Size Standards

Paper sizes vary around the world, with two main systems in use:

Quick Comparison: The most common sizes are US Letter (8.5" × 11") and ISO A4 (210 × 297mm or 8.27" × 11.69"). A4 is slightly narrower and taller than Letter.

US/Imperial Paper Sizes

The United States uses a system of paper sizes based on inches, with no consistent mathematical relationship between sizes.

Common US Paper Sizes

Letter (8.5" × 11")

Legal (8.5" × 14")

Tabloid/Ledger (11" × 17")

Half Letter (5.5" × 8.5")

Junior Legal (8" × 5")

ISO Paper Sizes (International Standard)

The A series shown as repeated halving: an A0 sheet divided into A1, that half divided into A2, and so on down to A6, each region shaded and labelled.
Each A size is the one before it folded in half across the long edge. The proportions never change, which is why scaling A3 artwork down to A4 never leaves an odd margin.

The ISO 216 standard defines paper sizes used in most of the world. The system is based on a consistent aspect ratio of √2:1 (approximately 1.414:1), which has the unique property that when you cut or fold the paper in half, the resulting pieces maintain the same aspect ratio.

The √2 Advantage: The ISO system's aspect ratio means that scaling between sizes is seamless. An A4 page folded in half becomes A5, and two A4 sheets side-by-side equal A3. This mathematical elegance makes the system highly practical.

ISO A Series (Most Common)

The A series is the most widely used and is based on A0, which has an area of 1 square meter.

A0 (841 × 1189mm)

A1 (594 × 841mm)

A2 (420 × 594mm)

A3 (297 × 420mm)

A4 (210 × 297mm) Most Common

A5 (148 × 210mm)

A6 (105 × 148mm)

ISO B Series

The B series is a geometric mean between consecutive A sizes, used when A sizes don't quite fit the need.

Common B Sizes

ISO C Series (Envelopes)

The C series is designed for envelopes. A C-size envelope fits an A-size sheet unfolded.

Common C Sizes

A4 vs Letter: Key Differences

A4 and US Letter overlaid from a shared bottom-left corner. Letter is six millimetres wider and A4 is eighteen millimetres taller, and the two strips that belong to only one of them are shaded and dimensioned.
The overlap is what prints safely on both. Anything in a shaded strip is what gets clipped when the wrong size is selected.

Since these are the two most common paper sizes worldwide, understanding their differences is important:

Dimension Comparison

Key Differences

Practical Implications

Choosing the Right Paper Size for Graph Paper

A sheet with its unprintable border shaded around all four edges, the printable area marked inside it, and a grid sized to finish on a whole square within that area instead of being cut off mid-square.
No consumer printer reaches the paper edge. Sizing the grid to end on a whole square inside the printable area avoids a fringe of slivers.

For Mathematics and Education

For Engineering and Technical Work

For Personal Organization

For Home and Garden Planning

For Art and Design

Paper Size Selection Tips

Consider Your Location

Consider Your Printer

Consider Your Project

Custom Paper Sizes

Our graph paper generator allows you to create graph paper in any custom size:

Quick Reference Table

US Sizes

ISO A Series

Pro Tip: When creating graph paper, always match your paper size selection to the actual paper loaded in your printer to avoid scaling issues and ensure accurate grid dimensions.

Generate your custom graph paper now with the exact paper size you need!

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