Fractions and Decimals | Czech Grammar

Fractions and decimals in Czech follow their own quiet logic, and two things ambush English speakers right away. First, Czech writes decimals with a comma, not a point: 3,5, never 3.5. Second, the thing being divided — the "whole" — goes into the genitive: a third of the cake is třetina koláče, with no separate word for "of." This page covers the fraction nouns (polovina, třetina, čtvrtina…), the everyday word půl, how to count fractions above one, and how to read a decimal out loud.

Fractions are feminine nouns

Czech fractions are feminine nouns built from the ordinals, almost all ending in -ina. The exception is "half," which has several everyday words.

Fraction	Czech
1/2	polovina, půlka (informal), půl
1/3	třetina
1/4	čtvrtina
1/5	pětina
1/6	šestina
1/10	desetina
1/100	setina

The whole that gets divided goes into the genitive — this is the same partitive "of" logic you meet after quantities everywhere in Czech.

Snědl jsem třetinu koláče.

I ate a third of the cake. (koláč → koláče)

Polovina obyvatel žije ve městech.

Half the inhabitants live in cities. (obyvatelé → obyvatel)

Counting the fraction: 2–4 versus 5 and up

A fraction noun can itself be counted — two thirds, five sixths — and when it is, it obeys the ordinary Czech number rule. Because the fraction noun is feminine, "two" is dvě and "one" is jedna.

Number	Form	Example
1	nominative singular	jedna třetina
2, 3, 4	nominative plural	dvě / tři / čtyři třetiny
5+	genitive plural	pět třetin, šest šestin

Dvě třetiny studentů u zkoušky uspěly.

Two thirds of the students passed the exam. (dvě → třetiny)

Zbývají nám tři čtvrtiny cesty.

We have three quarters of the journey left. (tři → čtvrtiny)

Pět šestin rozpočtu jde na platy.

Five sixths of the budget goes on salaries. (pět → šestin, genitive plural)

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The fraction noun follows exactly the same 1 / 2–4 / 5+ split as any counted noun in Czech. If you've learned that pět korun takes the genitive plural, then pět třetin does too — same rule, new noun. See five and up + genitive.

půl — the everyday "half"

půl is the workhorse word for "half" in daily life. It takes the genitive of what's being halved, and in normal use it is essentially indeclinable — it just sits there while the noun behind it bends.

Dej mi prosím půl litru mléka.

Give me half a litre of milk, please. (litr → litru)

Přijdu za půl hodiny.

I'll be there in half an hour. (hodina → hodiny)

Bydlel jsem tam jenom půl roku.

I only lived there for half a year. (rok → roku)

Půl Prahy bylo bez proudu.

Half of Prague was without power. (Praha → Prahy; verb stays neuter: bylo)

Its sibling čtvrt ("a quarter") behaves the same way — genitive, indeclinable:

Koupil jsem čtvrt kila šunky.

I bought a quarter kilo of ham. (kilo → kila)

For "and a half," add a půl to the whole number; the noun then sits in the genitive singular because of půl:

Trvalo to dvě a půl hodiny.

It took two and a half hours. (hodina → hodiny, genitive singular)

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Telling the time uses this same půl, but Czech counts toward the next hour: půl osmé is "half past seven" (literally "half of the eighth"). It catches every English speaker at least once. See telling the time.

Decimals: the comma and celá

Czech writes the decimal separator as a comma: 3,5 is read tři celé pět. The word celá means "a whole [unit]" and stands in for the comma. Crucially, celá is a feminine noun that agrees with the integer part, following the very same 1 / 2–4 / 5+ rule:

Number	Read as
1,5	jedna celá pět
2,5	dvě celé pět
3,5	tři celé pět
5,5	pět celý ch pět
0,5	nula celá pět

So it's jedna celá, then dvě / tři / čtyři celé, then pět celých — the integer drives the agreement just as it drives any other counted noun.

Pí se rovná přibližně tři celé čtrnáct.

Pi equals approximately 3.14. (tři → celé)

V neděli naměřili rekordních třicet osm celých dva stupně.

On Sunday they recorded a record 38.2 degrees. (38 ends in 'osm', so 5+ → celých)

For the ,5 case, everyday speech often swaps celá for the simpler a půl: 2,5 hodiny is just as naturally dvě a půl hodiny.

procenta — percentages

Percentages run on the same number rule, and the thing measured goes into the genitive. The noun procento has three shapes: jedno procento (1), procenta (2–4), procent (5+).

Pět procent obyvatel nemá práci.

Five percent of the inhabitants have no work. (pět → procent; obyvatel genitive)

O víkendu byla v obchodě sleva dvacet procent.

There was a twenty percent discount in the shop at the weekend.

For the finer points — decimals with percentages, "percentage points," degrees — see percentages and degrees.

Source comparison

The decimal mark is reversed. English 3.5 becomes Czech 3,5; and where English groups thousands with a comma (1,000), Czech uses a thin space or a dot (1 000). Writing the English way will be misread. See decimal comma and number spelling.
No separate word for "of." English "a third of the cake" becomes the bare genitive třetina koláče — the case carries the "of."
No article in "half an hour." English needs an; Czech just says půl hodiny, genitive and article-free.

Common Mistakes

❌ Pí je přibližně tři tečka čtrnáct.

Incorrect — Czech reads the decimal with celá and writes it with a comma, not a point.

✅ Pí je přibližně tři celé čtrnáct.

Pi is approximately 3.14.

❌ Snědl jsem třetinu koláč.

Incorrect — the divided whole goes into the genitive: koláč → koláče.

✅ Snědl jsem třetinu koláče.

I ate a third of the cake.

❌ Dvě třetina hlasovaly pro.

Incorrect — 2–4 take the nominative plural of the fraction: dvě třetiny.

✅ Dvě třetiny hlasovaly pro.

Two thirds voted in favour.

❌ Pět třetiny rozpočtu.

Incorrect — 5+ takes the genitive plural: pět třetin.

✅ Pět třetin rozpočtu.

Five thirds of the budget.

❌ Přijdu za půl hodina.

Incorrect — půl governs the genitive: hodina → hodiny.

✅ Přijdu za půl hodiny.

I'll be there in half an hour.

Key Takeaways

Fractions are feminine nouns from the ordinals: polovina, třetina, čtvrtina, pětina…, and the divided whole is genitive (třetina koláče).
A counted fraction obeys 1 / 2–4 / 5+: jedna třetina, dvě třetiny, pět třetin.
půl (and čtvrt) takes the genitive and barely declines: půl hodiny, čtvrt kila.
Decimals use a comma, read with celá, which agrees with the integer: dvě celé pět, pět celých pět.
procento → procenta → procent follows the same 1 / 2–4 / 5+ rule.

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