The thickness of a sheet of paper is shown by its weight.

This is measured either in grams per square meter (gsm) or pounds (lb) per ream (500 sheets) of a given size .

¼"  =  6mm

3/8"  = 10mm

½  =  12mm

¾ "  = 19mm

Foolscap octavo F8 6 x 4

Crown octavo C8 7 x 5

Large crown octavo lC8* 8 x 5

Demy octavo D8 8 x 55/8

Medium octavo M8 9 x 6

Royal octavo R8 10 x 6

Imperial octavo Imp8 11 x 7

Foolscap quarto F4 8 x 6

Crown quarto C4 10 x 7

Demy quarto D4 11 x 8

Medium quarto M4 12 x 9

Royal quarto R4 12 x 10

Imperial quarto Imp4 15 x 11

Foolscap folio Ffol 13 x 8

Crown folio Cfol 15 x 10

Royal folio Rfol 20 x 12

Imperial folio Impfol 22 x 15

British paper sizes

Royal 20 x 25 Royal 8vo 61/8 x 97/8

Royal, Double 25 x 40 Royal 4to 97/8 x 123/8

Crown, Double 20 x 30 Boards

Crown, Quad 30 x 40 Index Boards

Imperial 22 x 30 Index Royal 20 x 25

Imperial, Double 30 x 44