First-syllable word stress

While the basic rule is simple—stress the first syllable—there are a few important details that affect the rhythm of a sentence:

• Primary one-syllable prepositions become the new first syllable: Basic short prepositions (like na, za, or do) fuse with the following word to form a single rhythmic unit (a prosodic word). Because the basic rule is to always stress the first syllable, the stress naturally falls on the preposition. For example, do Prahy (to Prague) is pronounced as DO-pra-hy. Just like nouns, pronouns lose their stress to the preposition (e.g., pro mě is pronounced PRO-mě, bez něj is pronounced BEZ-něj). If an adjective comes before the noun, the preposition fuses with the adjective instead (e.g., do velkého města is pronounced DO-vel-ké-ho MĚS-ta). Exceptions: Certain prepositions (like skrz) are secondary prepositions (derived from other parts of speech). They do not steal the stress from the following noun; instead, they either retain their own stress or are completely unstressed, leaving the main stress on the noun (e.g., skrz okno is pronounced skrz OK-no or SKRZ OK-no). Also, if the following word is unusually long (usually 5 or more syllables), it is common and natural to shift the stress to the noun (e.g., do ČES-ko-slo-ven-ska). However, stressing the preposition (DO-čes-ko-slo-ven-ska) remains completely correct in standard pronunciation. Finally, if you want to emphasize the word (contrastive stress), the stress stays on the word: do Prahy, ne do Brna (to Prague, not to Brno) is pronounced do PRA-hy, ne do BR-na. Note: Failing to stress the preposition is a common marker of a foreign accent. DO-pra-hy is the natural pronunciation in both formal and casual speech.
• Glottal stop (ráz): When a preposition ends in a consonant and the following word begins with a vowel (like pod oknem), standard Czech inserts a slight catch in the throat called a glottal stop before the vowel. This prevents the words from linking smoothly together like they do in English or French. It is pronounced POT-'ok-nem (the glottal stop acts as a voiceless boundary, causing the preceding consonant to devoice). However, in fluent speech, the glottal stop is frequently omitted, causing the preposition to fully fuse with the noun (e.g., PO-dok-nem). This resyllabification is fully standard and correct.
• Non-syllabic prepositions: Prepositions without a vowel (k, v, s, z) attach to the word but cannot take the stress. The stress stays on the first syllable of the word. Note that these prepositions often change their sound to match the following consonant due to voicing assimilation, so v Praze (in Prague) is pronounced f-PRA-ze. However, when these prepositions gain a vowel to break up consonant clusters or when the following word starts with the same or a similar consonant (ke, ve, se, ze), they become syllabic and steal the stress just like primary prepositions (e.g., ve škole is pronounced VE-ško-le, ve vodě is pronounced VE-vo-dě).
• Two-syllable prepositions: Words like vedle or kolem carry their own word stress on the first syllable and do not steal the main stress from the following word. They do not fuse into a single stress unit like short prepositions do. For example, vedle auta is pronounced VED-le AU-ta (with two distinct stresses), but never VED-le-au-ta.
• Clitics are unstressed: Short grammatical words cannot take stress. Enclitics (like the ones in second-position clitics) lean on the word before them. For example, jmenuju se (my name is) is pronounced JME-nu-ju-se. On the other hand, proclitics (like short conjunctions such as a, i, že) lean forward onto the next word. For example, a proto (and therefore) is pronounced a-PRO-to.
• Secondary stress: Words with 3 or more syllables can take a weaker secondary stress on odd syllables (third, fifth) to maintain a regular rhythm. However, this secondary stress is extremely weak and more of a rhythmic feeling rather than a clearly audible stress.

Remember to keep all your vowels clear! English speakers often mumble unstressed syllables, but Czech has no vowel reduction. Every vowel must be fully pronounced, even if it doesn't have the stress. Also, do not confuse stress with long vowel letters—they are completely separate systems!