There are several methods for the romanization of Greek, especially depending whether the language written with Greek letters is Ancient Greek or Modern Greek and whether a phonetic transcription or a graphemic transliteration is intended.

Table

This table lists several transcription schemes from the Greek alphabet to the Latin alphabet.

Greek	Ancient			Modern
	Clas- sical	Scien- tific	Beta code	ISO	BGN/ PCGN	UN/ ELOT	Greeklish†
α	a	a	A	a	a	a	a
β	b	b	B	v	v	v	b, v
γ	g	g	G	g	g, y1	g	g, y
δ	d	d	D	d	dh, d2	d	d
ε	e	e	E	e	e	e	e
ζ	z	z, (dz)	Z	z	z	z	z
η	e	ē	H	í	i	i	h, i
θ	th	th	Q	th	th	th	th
ι	i	i	I	i	i	i	i
κ	c	k	K	k	k	k	k, c
λ	l	l	L	l	l	l	l
μ	m	m	M	m	m	m	m
ν	n	n	N	n	n	n	n, v
ξ	x	x	C	x	x	x	ks, x
ο	o	o	O	o	o	o	o
π	p	p	P	p	p	p	p
ρ	r, rh3	r, (rh3)	R	r	r	r	r
σ	s	s	S	s	s4	s	s
τ	t	t	T	t	t	t	t
υ	y	y, (u)	U	y	i	y	y
φ	ph	ph	F	f	f	f	f, ph
χ	ch	ch	X	ch	kh	ch	ch, x, h
ψ	ps	ps	Y	ps	ps	ps	ps
ω	o	ō	W	ō	o	o	w, o

Vowel digraphs11
Greek	Ancient			Modern
	Clas- sical	Scien- tific	Beta code	ISO	BGN/ PCGN	UN/ ELOT	Greeklish†
αι	ae, e	ai	AI	ai	e	ai	ai, e
αυ	au	au	AU	au	av	av5, af6	ay, au, af, av
ει	i	ei	EI	ei	i	ei	ei, i
ευ	eu	eu	EU	eu	ev	ev5, ef6	ey, eu, ef, ev
ηυ	eu	ēu	HU	īy	iv	iv5, if6	hy, hu, if, iv
οι	oe, e	oi	OI	oi	i	oi	oi, i
ου	u	ou	OU	ou	u	ou	ou, u, oy
υι	ui	ui	UI	yi	i	yi	yi, gi, i

Consonant digraphs
Greek	Ancient			Modern
	Clas- sical	Scien- tific	Beta code	ISO	BGN/ PCGN	UN/ ELOT	Greeklish†
γγ	ng	ng	GG	gg	ng	ng	gg, gk, ng
γξ	nx	nx	GC	gx	nx	nx	gks, gx
γκ	nc	nk	GK	gk	g7, ng8	gk	gk
γχ	nch	nch	GX	gch	nkh	nch	nx, nch
μπ	mp	mp	MP	mp	b7, mb8	b7, mp8	mp, b, mb
ντ	nt	nt	NT	nt	d7, nd8	nt	nt, d, nd

Modifiers (only classical Greek)
Greek	Ancient
	Clas- sical	Scien- tific	Beta code
̔	h9	h9	(	(spiritus asper, δασεῖα)
̓	none	none	)	(spiritus lenis, ψιλή)
ͺ	i?	i?	|	(iota subscript, ὑπογεγραμμένη)10

Archaic letters
Greek	Ancient
	Clas- sical	Scien- tific	Beta code
ϝ	w		V	(digamma)
ϛ	st		#2	(stigma)
ͱ	h9		h9	(heta)
ϻ	s, ś		#711	(san)
ϸ	sh			(sho)
ϟ	q		#3	(qoppa)
ϡ	ss		#5	(sampi)

Special letter
Greek	Ancient
	Clas- sical	Scien- tific	Beta code
ȷ	j			(yot)

Notes:

1. before αι, ε, ει, η, ι, οι, υ, υι.
2. between ν and ρ.
3. with spiritus asper.
4. sometimes doubled between vowels (ex. Larissa).
5. before β, γ, δ, ζ, λ, μ, ν, ρ and vowels.
6. before θ, κ, ξ, π, σ, τ, φ, χ, ψ and at the end of a word.
7. at the beginning of a word.
8. in the middle of a word.
9. on vowel: h before the vowel; on ρ: rh.
10. under long vowels.
11. except when there is a diaeresis ( ¨ ) on the second vowel

† The use of 'Greeklish' (here: writing Greek in the Latin alphabet) has risen enormously with the advent of SMSs, email, online chatting, and other digital media, where Greek fonts are not always readily available.

Examples:

Θέλω → Thelo
Ξανά → Ksana or Xana etc
Ψυχή → Psyhi etc

Diacritics

The traditional polytonic orthography of Greek uses several distinct diacritic signs to render what was originally the pitch accent of Ancient Greek, and the presence or absence of word-initial h. In 1982, monotonic orthography was officially introduced for modern Greek. The only diacritics that remain are the acute accent (indicating stress) and the diaeresis (indicating that two consecutive vowels should not be combined). The acute accent and the diaeresis are kept in both the BGN/PCGN and the UN/ELOT romanization systems. There is one exception: in the vowel combinations αυ, ευ and ηυ the accent moves from the υ (that becomes v or f) to the preceding vowel.

See also

12. Beta code
13. Classical compound
14. English words of Greek origin
15. List of Latin and Greek words commonly used in systematic names for help with Greek-derived scientific names of organisms
16. List of Greek words with English derivatives

References

• Transliteration of Non-Roman Scripts, a collection of writing systems and transliteration tables, by Thomas T. Pedersen. Includes PDF reference charts for many languages’ transliteration systems.
• The Working Group on Romanization Systems of the United Nations.
• Transliteration chart of the Library of Congress.
• Online transliteration tool (Greek characters into Latin characters), based on the ELOT 743 (ISO 843) standard - Free php tool hosted on a translation-related website (Lexicon SA Greece).