Age, Height, and Measurement Expressions | Icelandic Grammar

Saying how old you are, how tall, and how warm it is outside are bread-and-butter conversations, and Icelandic handles them with a couple of fixed idioms that look strange until you see the grammar inside. The headline surprise: age uses a frozen genitive — Ég er þrítugur is one option, but the everyday "I'm thirty" is Ég er 30 ára, where ára ("of years") never changes no matter the number. This page covers age, the age question (which agrees with your gender), height and weight, the measurement nouns, and temperature. Number declension for 1–4 lives on its own page; here we focus on the idioms.

Age: the frozen genitive ára

To say your age, you use the number plus ára — and ára is invariant. It is, historically, the genitive plural of ár (hk, "year"): þrjátíu ára means literally "of thirty years." Once you know that, the strangeness dissolves — it is the same logic as English "a man of thirty years," frozen into a fixed phrase. Whatever the number, ára stays ára: never ár, never árir, never a plural that agrees.

Icelandic	English
Ég er fimm ára.	I am five years old.
Ég er þrjátíu ára.	I am thirty years old.
Hún er sextán ára.	She is sixteen years old.
Hann er hundrað ára.	He is a hundred years old.

You do not add a word for "old" — ára carries the whole meaning. Ég er 30 ára is complete; there is no *gamall tacked on. (English "thirty years old" tempts you to translate "old," but Icelandic doesn't.)

Ég er þrjátíu og fimm ára.

I am thirty-five years old. 'ára' stays ára — it's a frozen genitive plural, the same for every number.

Strákurinn er bara fjögurra ára.

The boy is only four years old. Note: with 1–4 the NUMBER goes genitive too — fjögurra (gen. of fjögur) + ára.

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ára is the genitive plural of ár ("of years") and never changes. "Thirty years old" = þrjátíu ára, "two years old" = tveggja ára. Don't make it agree, don't add a word for "old" — ára does it all.

With 1–4, the number goes genitive too

Here is the subtlety that trips people up. Because ára is a genitive ("of _ years"), the number in front of it must also be genitive — but only the numbers 1–4 actually have distinct genitive forms (5 and up don't change). So for small ages you get:

Age	Icelandic	Number form
1	eins árs	eins (gen) + árs (gen sg!)
2	tveggja ára	tveggja (gen of tveir)
3	þriggja ára	þriggja (gen of þrír)
4	fjögurra ára	fjögurra (gen of fjögur)
5+	fimm ára, sex ára ...	number unchanged

Watch the special case of "one year old": it is eins árs — the singular genitive árs, because "one" is singular. Everything from two up uses the plural genitive ára. So þriggja ára "three years old" stacks two genitives: þriggja (gen. of þrír) + ára (gen. pl. of ár).

Barnið er bara eins árs.

The child is just one year old. Singular: 'eins árs' (one + singular genitive árs), not 'eins ára'.

Dóttir mín er þriggja ára.

My daughter is three years old. 'þriggja' (gen. of þrír) + 'ára' — two genitives stacked.

Asking someone's age: gamall / gömul

The age question uses the adjective gamall ("old"), and here the adjective must agree with the gender of the person you're asking:

Hvað ertu gamall? — to a male (gamall, masculine)
Hvað ertu gömul? — to a female (gömul, feminine)

The vowel change gamall → gömul is the u-umlaut (a → ö before a feminine ending). Get the gender wrong and you've effectively misgendered the listener, so it's worth locking in. The answer, of course, comes back with the frozen ára:

Hvað ertu gamall? — Ég er tuttugu og fimm ára.

How old are you? (to a man) — I'm twenty-five. Question uses masculine 'gamall'; answer uses frozen 'ára'.

Hvað ertu gömul? — Ég er nítján ára.

How old are you? (to a woman) — I'm nineteen. Feminine 'gömul' (u-umlaut of gamall).

Hvað er hún gömul?

How old is she? Feminine subject 'hún' → 'gömul'.

For a child of unknown or neuter reference (barnið, n) you'd use gamalt: Hvað er barnið gamalt? So the adjective has three genders — gamall (m), gömul (f), gamalt (n) — and you pick the one matching the person.

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The age question agrees with the listener's gender: gamall to a man, gömul to a woman, gamalt for a neuter noun like barn. The answer always uses frozen ára.

Height and weight

For height Icelandic uses á hæð ("in height," with hæð kvk "height" in the dative), and the measurement is read like a decimal said as two numbers. 1,80 m is read einn áttatíu ("one eighty") — the metre and the centimetres, no word for "point":

Icelandic	English
Ég er einn sjötíu á hæð.	I'm 1.70 tall.
Hann er einn áttatíu á hæð.	He's 1.80 tall.
Hún er einn sextíu og fimm.	She's 1.65 (the 'á hæð' is often dropped).

Note that Icelandic, like the rest of Europe, writes the decimal with a comma: 1,80, not 1.80. For weight you use the verb-free frame with kíló (hk) or simply vega ("to weigh"): Ég er áttatíu kíló "I weigh eighty kilos," or Ég vigta áttatíu kíló.

Ég er einn áttatíu á hæð.

I'm 1.80 tall. Read '1,80' as 'einn áttatíu' — one (metre) eighty (cm), no word for 'point'.

Hann er einn sjötíu og vigtar sjötíu kíló.

He's 1.70 and weighs seventy kilos. 'einn sjötíu' = 1.70; 'kíló' (hk) stays singular here.

The measurement nouns

These are the everyday units, with their genders (most are loanwords):

Icelandic	Gender	English
metri	kk	metre
sentimetri	kk	centimetre
kílómetri	kk	kilometre
kíló (kílógramm)	hk	kilo(gram)
gramm	hk	gram
lítri	kk	litre
gráða	kvk	degree

The -i units — metri, sentimetri, lítri — are weak masculine nouns (kk) and take the plural -ar: tveir metrar, þrír lítrar. Kíló and gramm are neuter (hk) and, conveniently, don't change in the plural (tvö kíló, fimm hundruð grömm — though gramm does take the u-umlaut plural grömm).

Það eru fimm kílómetrar í næsta bæ.

It's five kilometres to the next town. 'kílómetrar' — weak masculine plural -ar.

Get ég fengið hálft kíló af osti?

Can I have half a kilo of cheese? 'kíló' (hk) — half a kilo = hálft kíló (neuter agreement).

Temperature: gráða and stiga hiti

Temperature has two common patterns. The first uses gráða (kvk, "degree") in the plural gráður: Það eru tíu gráður "it is ten degrees." The second, more idiomatic, uses stiga hiti — stiga is the genitive plural of stig (hk, "degree/point"), and hiti (kk) is "heat/warmth," so tíu stiga hiti is literally "ten-degrees' warmth":

Icelandic	English
Það eru tíu gráður.	It's ten degrees.
Það er tíu stiga hiti.	It's ten degrees (of warmth).
Það er fimm stiga frost.	It's minus five (five degrees of frost).

For below-zero temperatures Iceland naturally says frost (hk): fimm stiga frost "five degrees of frost" = −5 °C. You can also say mínus fimm gráður, but stiga frost is more idiomatic for the cold.

Það er tíu stiga hiti úti í dag.

It's ten degrees out today. 'stiga' = gen. pl. of stig; 'hiti' = warmth — '(of) ten degrees warmth'.

Í gær var fimm stiga frost.

Yesterday it was minus five. 'stiga frost' is the idiomatic way to say below-zero.

Common Mistakes

❌ Ég er þrjátíu ár.

Incorrect — age uses the frozen genitive 'ára', not the nominative 'ár'.

✅ Ég er þrjátíu ára.

I'm thirty years old.

❌ Ég er þrjátíu ára gamall.

Awkward/redundant — 'ára' already means 'years old'; don't add 'gamall' in the statement.

✅ Ég er þrjátíu ára.

I'm thirty years old. ('gamall' belongs in the QUESTION, not the answer.)

❌ Hvað ertu gamall? (said to a woman)

Incorrect — the adjective must agree with the listener's gender; use 'gömul' for a woman.

✅ Hvað ertu gömul?

How old are you? (to a woman)

❌ Barnið er eins ára.

Incorrect — 'one' is singular, so use the singular genitive 'árs': eins árs.

✅ Barnið er eins árs.

The child is one year old.

❌ Það eru tíu gráða.

Incorrect — 'ten degrees' is plural: gráður, not the singular gráða.

✅ Það eru tíu gráður.

It's ten degrees.

Key Takeaways

Age = number + ára, where ára (gen. pl. of ár) is frozen — same for every number, and it already means "years old," so don't add gamall.
With 1–4 the number is genitive too: eins árs (1, singular!), tveggja ára, þriggja ára, fjögurra ára.
The age question agrees with the listener: gamall (m) / gömul (f) / gamalt (n).
Height: einn áttatíu á hæð (1,80) — read the decimal as two numbers, comma not point.
Measurement nouns: metri, lítri (kk, plural -ar); kíló, gramm (hk, no plural change); gráða (kvk).
Temperature: tíu gráður or tíu stiga hiti; below zero: fimm stiga frost.

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