How to Calculate Paper Size Converter

What is Paper Size Converter?

ISO 216 defines the A-series paper sizes (A4, A3, A0...) using a √2:1 ratio so each size is exactly half the area of the one above. A4 (210×297mm) is the global standard.

Formula

A-series: A0=1 m² | Each step (A1, A2...) = previous / 2 | B-series: between A sizes | C-series: envelope sizes

Step-by-Step Guide

1A0 = 841×1189mm (exactly 1m² area)
2Each subsequent size = fold in half along long edge
3√2:1 aspect ratio preserved throughout the series
4US Letter = 216×279mm (slightly different ratio)

Worked Examples

Input

A4 dimensions

Result

210 mm × 297 mm = 8.27" × 11.69"

Frequently Asked Questions

What is Paper Size?

ISO 216 defines the A-series paper sizes (A4, A3, A0. ) using a √2:1 ratio so each size is exactly half the area of the one above

How accurate is the Paper Size calculator?

The calculator uses the standard published formula for paper size. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

What units does the Paper Size calculator use?

This calculator works with inches, square metres. You can enter values in the units shown — the calculator handles all conversions internally.

What formula does the Paper Size calculator use?

The core formula is: A0 = 841×1189mm (exactly 1m² area). Each step in the calculation is shown so you can verify the result manually.

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