papersizes-guide

Every standard paper size, offline. No network calls, no API key, no dependencies.

Covers 324 sizes across 23 series: ISO A, B and C, US and ANSI, ARCH, envelopes, photo prints, business and ID cards, book trim sizes, newspapers, billboards, and regional standards from Japan, China, France, Canada, Colombia and the British Imperial system.

pip install papersizes-guide

Use

import papersizes_guide as paper

a4 = paper.get("A4")
a4.width_mm        # 210.0
a4.height_in       # 11.69
a4.pixels(300)     # (2480, 3508)
a4.ratio_label     # '1:√2'
a4.weight(80)      # 4.992  (grams, one sheet at 80 gsm)

Look a size up by slug, name or alias:

paper.get("a4")
paper.get("DIN A4")
paper.get("No. 10 envelope")

Identify a sheet you have measured. Orientation does not matter:

paper.find(8.5, 11, unit="in")[0].size.name   # 'Letter'
paper.find(216, 356)[0].size.name             # 'Legal'
paper.find(297, 210)[0].rotated               # True — that is A4, turned

Work with a whole series:

[s.name for s in paper.series("a")]   # A0 … A10, plus 2A0 and 4A0
paper.series_list()                   # every series with its governing standard

Why derived, not stored

Only the millimetre dimensions are stored. Inches, points, pixels, ratio, area and sheet weight are properties computed on access, so the package cannot contradict itself and adding a resolution costs nothing.

API

Each PaperSize exposes width_mm, height_mm, width_cm, height_cm, width_in, height_in, width_pt, height_pt, ratio, ratio_label, area_mm2, area_m2, diagonal_mm, orientation, plus pixels(dpi) and weight(gsm). Frozen dataclasses, fully typed, py.typed included.

When two sizes share exact dimensions, such as Letter and ANSI A, find returns the more familiar one first.

Data and licence

The dataset comes from papersizes.guide and is released under CC BY 4.0. Use it commercially, modify it, redistribute it. The only condition is credit.

ISO and ANSI values are generated from the standard formulas rather than transcribed. Regional and historical sizes are cross-checked against at least two published references, and any size whose sources disagree carries a note on its page. The full process is documented at papersizes.guide/methodology.

To cite the dataset:

PaperSizes.guide paper size dataset, version 2026.09.07.
https://papersizes.guide/data/ — CC BY 4.0

A live REST API of the same data, with no key, is documented at papersizes.guide/data.

Found an error in a dimension? Report it and it will be corrected with the correction noted.

Source, and where to report a wrong dimension in code: github.com/nanosani/papersizes-guide.