German Age and Birthday Questions: Parsing the Numbers

Wie alt bist du? is one of the first questions you can answer in German, and one of the first you fail at when the reply comes back fast. Age and birthdays are everywhere in small talk, on forms read aloud, at parties, in introductions, and the whole exchange almost always hinges on a single number: an age, a birth year, a date. Miss that number and you have understood the entire sentence except the one word that mattered.

The catch is that age and birthday talk packs three different number patterns into a few short questions. An age is a reversed two-digit number. A birthday is a spoken date with an ordinal. A birth year follows its own rules and switches form completely after the year 2000. This guide walks through each one as it actually sounds, so the next time someone asks wann bist du geboren, the year lands cleanly.

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Asking and answering age

The question comes in two registers, informal and formal, and you should know both by ear because the answer is identical either way:

Two things to notice. First, Jahre alt ("years old") is optional and gets dropped constantly, so the whole answer is often just Ich bin plus a number. Second, the verb werden ("to become") is how you say turning an age: Ich werde vierzig means I'm turning forty. In both cases the number is the only part carrying information, which is exactly what makes age so unforgiving to mishear.

How German age numbers sound out loud

An age is a plain cardinal number, which means everything you know about reversed German numbers applies. From 21 upward the units come before the tens, so the age is spoken back-to-front:

Because acht and achtundzwanzig start the same way, your brain wants to commit to "eight" before the undzwanzig arrives. Hold off. If two-digit numbers still slip past you in general, age questions are a good reason to drill the numbers 1 to 100 until they are automatic.

Children's ages add one wrinkle: they are often given in halves. A small child is zweieinhalb (two and a half) or viereinhalb (four and a half), with -einhalb tacked straight onto the number. It is the same halb you meet in spoken fractions, just fused into a single word.

Birthday questions and dates

A birthday question wants a date, not an age, and the answer switches to ordinals:

The day is an ordinal with a -ten ending (fünfzehnten, dritten), and it works exactly like any other spoken German date. Milestone birthdays get their own flavour. A birthday that lands on a round decade is a runder Geburtstag, and the birthday number itself often shows up as an ordinal noun:

• Sie feiert ihren Fünfzigsten. — She's celebrating her fiftieth.
• Wir sind auf seinem Vierzigsten. — We're at his fortieth.
• Herzlichen Glückwunsch zum Dreißigsten! — Happy thirtieth!

The -sten ending is the tell: dreißig is the age thirty, but Dreißigsten is the thirtieth birthday. Same root, different job.

Birth years: the two patterns

Ask Wann bist du geboren? ("When were you born?") and the answer is a four-digit year, said by ear in one of two completely different ways depending on whether it falls before or after 2000.

Years up to 1999 are built in hundreds: neunzehnhundert… ("nineteen hundred…") followed by the last two digits, themselves reversed. Years from 2000 on simply start with zweitausend and add the rest. There is no zwanzighundert for 2024, so a learner who expects the hundreds pattern to continue gets stranded the moment a recent year comes up. The mechanics of stacking hundreds into one long word are the same as in any larger spoken number; the only new thing is which century word leads.

You will also hear birth years framed as a Jahrgang (a birth cohort): Ich bin Jahrgang achtundsiebzig means I was born in '78. Same number, just labelled as the year-group rather than spelled out as a full year.

Vague ages: Anfang, Mitte, Ende

Germans often give an approximate age rather than an exact one, and these forms are common in gossip, descriptions, and dating-app talk:

Here the decade word is the anchor (zwanzig, dreißig, vierzig) and the framing word (Anfang, Mitte, Ende) tells you where in the decade. Listen for the pair together: missing the Mitte in Mitte dreißig leaves you thinking someone said an exact thirty.

The listening traps

Four things make age and birthday numbers harder than the tables look:

• The age is reversed. Sechsundsiebzig is 76, not 67. The units land first, so wait for the whole word before you settle on a number.
• Age versus birth year. The cue word decides the shape of the answer. After Wie alt… you expect a small two-digit number; after Wann… geboren you expect a four-digit year said in hundreds or thousands. Catch the question word and you know what kind of number is coming.
• Two year patterns. Neunzehnhundert… versus zweitausend… sound nothing alike, and there is no bridge form for the 2000s. Train both so a recent birth year does not throw you.
• Cardinal versus ordinal birthdays. Vierzig is the age forty; Vierzigsten is the fortieth birthday. The extra -sten ending is small and easy to miss at speed.

Catching age numbers by ear: a listening routine

Reading these tables is the easy part. Catching achtundzwanzig the instant someone answers wie alt bist du, or pulling neunzehnhundertzweiundneunzig out of a fast introduction, is the real skill. A short routine that builds it:

1. Lock onto the question word. Alt means an age is coming; geboren means a year. Knowing the shape in advance halves the work.
2. Wait for the whole number. Practise holding off until the word finishes, so achtundzwanzig never collapses into acht in your head.
3. Drill both year patterns. Run neunzehnhundert… and zweitausend… years back to back until switching between them is instant.
4. Practise in context, at speed. An age almost never arrives alone and slow. It is buried in Mein Bruder wird nächste Woche dreißig and gone in a beat, so practice that mirrors real speech is what actually transfers.

That last point is the whole reason Zahlhaus exists: real German voices, numbers at conversational speed, and instant scoring so you find out the moment sechsundsiebzig slips past as siebenundsechzig. It is the fastest way to train your ear for German numbers until ages, birthdays, and birth years land correctly without a second's hesitation.

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