Choosing ei vs ey | Icelandic Grammar

This is the sibling problem to i/y, and it bites for exactly the same reason: ei and ey are pronounced identically — both are the diphthong [ei], the "ay" of English day — so your ear cannot tell them apart. leið ("way") and leysa ("to solve") carry the same opening diphthong; only the spelling differs. As with i/y, the choice is therefore lexical and etymological, never phonetic: you decide by which root or word-family the word belongs to, not by listening. The default, by a wide margin, is ei; ey is the smaller, marked set you learn to spot. And there is a reliable trick for spotting it. (This page is only about ei/ey; the parallel i/y and í/ý problem lives on its own page.)

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The instinct to "sound it out" is useless here — ei and ey are perfect homophones. The useful instinct is the same as for i/y: stop listening and hunt for a related word, especially one with au, which betrays an ey.

Same sound, different letter

Reading is effortless: whether a word is written ei or ey, you say [ei], so you read aloud correctly on sight. Writing is where it bites — given a spoken word, nothing in the sound tells you which to write. bein ("bone") and þeysa ("to dash") rhyme perfectly; one takes ei, the other ey. Only history decides, and ei is the heavy default: the great majority of "ay"-words are spelled ei, and ey is the minority case you have to recognise.

leið — bein — steinn

way — bone — stone: three ordinary ei-words, the common default. Nothing special marks them; they simply are not ey-words.

heyra — eyra — leysa

to hear — ear — to solve/loosen: three ey-words pronounced exactly like ei-words, but written ey for historical reasons.

So leið ([leiːð]) and the first syllable of leysa ([ˈleiːsa]) carry the identical [ei] diphthong; only the spelling separates them. No amount of careful listening will help.

The default is ei

Because ei is so much more frequent, the safest baseline is: if you have no reason to write ey, write ei. A large share of everyday vocabulary is ei — einn ("one"), leið ("way"), heim ("home"), beint ("straight"), bein ("bone"), steinn ("stone"), heitur ("hot"), seinn ("late"), leika ("to play"), teikna ("to draw"). None of these has an au-relative or belongs to an ey-root, so none of them takes ey.

Förum beint heim — það er styttri leið.

Let's go straight home — it's the shorter way. beint, heim, leið: three plain ei-words, no ey anywhere.

Það er bara einn steinn eftir í veggnum.

There's only one stone left in the wall. einn, steinn: ordinary ei-words.

The ey set: roots and the island word

There is a smallish family of ey-roots you simply learn as ey-words, because ey is baked into the root. The most important is the word ey itself — ey / eyja ("island") — which shows up in countless place-names (Vestmannaeyjar, Heimaey, Surtsey) and as the suffix -ey. Alongside it sit a cluster of high-frequency roots:

heyra ("to hear"), and its relatives heyrn ("hearing"), áheyrandi ("listener")
eyra ("ear") — note: a different word from heyra, but both happen to be ey
eyða ("to destroy, to spend"), eyðimörk ("desert")
deyja ("to die"), dauði/deyja alternations
þeysa ("to dash, gallop")

Heyrðu, ég heyri ekkert í þér — talaðu hærra.

Hey, I can't hear you at all — speak up. heyra (and heyrðu) is an ey-root; don't be tempted by ei.

Hann fæddist í Vestmannaeyjum.

He was born in the Westman Islands. The place-name carries ey 'island' — eyjar is the plural.

Ég er búinn að eyða öllum peningunum.

I've spent all the money. eyða 'to spend/destroy' is an ey-root.

The reliable trick: an au-relative betrays ey

Here is the heuristic that does the real work, and it is the exact parallel of the i/y strategy. A great many ey-spellings are fossils of an au that was fronted to ey by i-umlaut. (I-umlaut is the older alternation that pulls a back vowel forward; au → ey is one of its outcomes.) That history leaves a clue: a related word in the same family still shows au. Find that au-relative, and the ey is justified — and predicted.

The cleanest case is laus → leysa:

laus ("loose, free") has au.
leysa ("to loosen, to solve, to release") is the derived verb, with the au fronted to ey.

The au in laus is exactly the signal that the verb is leysa (with ey), not *leisa. The same fossil links other pairs:

rjúka ("to smoke, billow") → reykur ("smoke"), Reykjavík ("Smoky Bay") — the jú/au-grade root surfaces as ey.
kaupa ("to buy") → keypti ("bought", past) — the au of the present fronts to ey in the past tense.
hraustur ("robust") → hreysti ("vigour") — au → ey in the derived noun.

Skórinn er laus — geturðu leyst skóreimina fyrir mig?

The shoe is loose — can you untie the lace for me? laus (au) → leysa/leyst (ey): the au-relative predicts the ey.

Ég keypti nýjan síma í gær.

I bought a new phone yesterday. kaupa (au) → keypti (ey): the past tense fronts au to ey.

Reykurinn liðast upp úr eldfjallinu.

The smoke is curling up out of the volcano. reykur is the ey-noun to the rjúka family — same au/ey fossil that gives Reykjavík its name.

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The single best test for ey: look for a relative with au. If one exists (laus → leysa, kaupa → keypti, rjúka → reykur), the fronted member is ey. No au-relative and not an ey-root? Default to ei.

Putting the two tests together

So the working procedure mirrors the i/y page exactly:

You are unsure whether a word takes ei or ey.
Is it one of the ey-roots (the ey "island" family, heyra, eyra, eyða, deyja, þeysa)? If yes, write ey.
Is there a related word with au? If yes, the fronted member is ey (laus → leysa).
If neither — no ey-root, no au-relative — default to ei (leið, bein, einn, heim).

This is spelling by family, not by ear — the strategy the whole spelling group rewards.

How this differs from English

English has no ei/ey homophone problem of this kind, and crucially no morphological tell behind its spellings. When English has variant spellings of the same sound (ei in receive, ey in key, ay in day), there is no living word-family rule that predicts them — you memorise each word. Icelandic is better behaved: the ey spelling is frequently the visible end of an au → ey alternation, so a related word actually tells you which to write. The skill an English speaker has to build is the one English never trained — instead of memorising each word blind, learn to look sideways to the family and let the au-relative decide.

Common Mistakes

❌ Defaulting to ei everywhere: writing 'heyra' as *heira

Incorrect — heyra is an ey-root. The ei default is only for words with no ey-root and no au-relative.

✅ heyra

to hear — fixed ey-root.

❌ Writing 'leysa' as *leisa, ignoring its relative laus

Incorrect — leysa is derived from laus (au), and that au is exactly the signal that the verb takes ey.

✅ laus → leysa

loose → to loosen/solve: au in the base → ey in the verb.

❌ Spreading ey onto a plain ei-word: writing 'leið' as *leyð

Incorrect — leið has no au-relative and no ey-root, so it is plain ei. ey is the marked minority case, not the default.

✅ leið

way — ordinary ei, no ey-fossil.

❌ Writing the past of kaupa as *keipti

Incorrect — the past tense fronts the au of kaupa to ey: keypti. The au-relative is the giveaway.

✅ kaupa → keypti

to buy → bought: au → ey in the past tense.

❌ Writing the island name element as *-ei (Vestmanna-eiar)

Incorrect — the word ey 'island' is the root; its plural is eyjar. Place-names with 'island' always take ey.

✅ Vestmannaeyjar

the Westman Islands — ey 'island'.

Key Takeaways

ei and ey sound identical ([ei], "ay"); the choice is etymological, never by ear.
The default is ei — far more frequent (leið, bein, einn, heim, steinn). ey is the marked minority case.
Write ey for the ey-roots: the word ey / eyja ("island") and its place-names, plus heyra, eyra, eyða, deyja, þeysa.
The reliable test: a related word with au betrays ey (laus → leysa, kaupa → keypti, rjúka → reykur) — the same au → ey i-umlaut fossil exploited for y/ý.
No ey-root and no au-relative? Default to ei.
Spell by family, not by sound — exactly as with i/y.

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