Skip to content
World Paper Index · since 2026 · 0 grades indexed

The reference
index of paper.

Every paper grade, mill, brand and certification, catalogued, cross-referenced and assigned a permanent WPI ID. Free, open, and obsessively maintained by people who love a good watermark.

0Grades indexedPermanent WPI IDs
0Mills catalogued0 countries
0CertificationsFSC · PEFC
0Editorial articleslong-form, sourced
API queries / moFree forever
Coating · top layer-01
Size press layer-02
Base fibre web layer-03
Size press layer-04
Coating · back layer-05
Reference · anatomy of a sheet

One sheet,
five questions.

What is the fibre? How is it held together? What is on its surface? How flat is it made? And how white is white? Every entry in the index answers those five questions, the same way, in the same order, every time.

That is why a WPI ID is useful: it pins one specific answer-set to one specific grade, forever. Mills change, brand names shift, but WPI-g-000001 is always the same indexed record.

Open the glossary →
Step · 01

Observe.

Trade catalogues, mill datasheets, ISO standards, customs codes. We read the boring stuff so you don't have to.

Step · 02

Normalize.

We reconcile a thousand trade names into one canonical grade with a single spec sheet and a permanent ID.

Step · 03

Cross-reference.

Every grade links to its mills, brands, certifications, and articles. Every mill links to every grade it runs.

Step · 04

Publish.

Free, open, CC-BY. No paywall, no login, no hidden “pro” tier.