EPER Levels for Graded Readers by Publisher, Series

			Penguin	Oxford				MacMillan		Cambridge
EPER level	Students	TOEFL/ TOEIC	P-GR	O-BW	O-FF	O-S	O-PER	H-NW	H-GR	CER
G	Starters	-/-	EasyStarts	-	-	-	-	1	Starter	-
F	Beginner	-/-	1	Starters	1	1	-	2,3	Beginner	-
E	Elementary	350/150	-	1	2	-	-	4	Beginner L	1
D	Low Int. (1)	400/300	2	2	3	2	1	5	Elementary	2
C	Intermediate	450/450	3	3	4	3,4	2	-	Intermediate	3
B	High Int. (2)	480/530	4	4	-	-	3	-	Upper Level	4
A	Advanced	520/650	5	5	-	-	4	-	-	5
X	Bridge	550/730	6	6	-	-	5	-	-	6

KEY

EPER: The Edinburgh Project on Extensive Reading. ..."seek[s] to promote the systematic use of graded readers within an extensive reading programme that forms an integral part of the ELT syllabus."
TOEFL: The Test of English as a Foreign Language
TOEIC: The Test of English for International Communication
P-GR: Penguin Graded Readers. Original titles, modified classics and movie novelizations for teen through adult.
O-WB: Oxford Bookworms. "The Oxford Bookworms Library [includes OFF, below] provides a wide range of carefully-graded reading material across six stages. Each book now incorporates an extensive Activities section. Activity Answer Keys, Tests, and Activity Worksheets are available for download."
O-FF: Oxford (Bookworms) Fact Files (non-fiction)
O-S: Oxford Storylines. "Storylines offer a motivating selection of short, original stories - from mystery and humour to science fiction and ghost stories. Graded at four levels, all the titles are illustrated in colour and are available on cassette."
O-PER: Oxford Progressive English Readers. "Adaptations of popular classics and modern fiction [for] young adults and adults."
H-NW: MacMillan (old Heineman) New Wave
H-GR: MacMillan (old Heineman) Guided Readers
CER: Cambridge English Readers
(1): Transition to L1 for 10-12 year olds.
(2): Transition to L1 for 13-15 year olds.

Sources:
Hill, David R.; Graded (Basal) Readers -- Choosing The Best, The Language Teacher: Issue 21.05 - May 1997
Hill, David R.; Graded Readers, ELT Journal, Volume 55/3 July 2001

This table reflects several changes that have taken place since the publication of the original data in Hill (1997). Publishers have merged titles into fewer series and some new levels have been added in some series.

This table should be considered as a guide only. Hill's data reflect substantial research into the average reading difficulty of the various series' levels, whereas my modifications are simply guesses made necessary by the various publishers' changes. Teachers should always consider the needs and interests of their students.