Dass or Ob

Q: What are common mistakes with Dass or Ob?

Ich frage, dass er kommt → Ich frage, ob er kommt: When asking a question or expressing uncertainty, use 'ob' (whether), not 'dass' (that). Ich weiß, ob er kommt → Ich weiß, dass er kommt: When stating something you know for certain, use 'dass' (that), not 'ob' (whether). Ich weiß nicht, dass er kommt → Ich weiß nicht, ob er kommt: When expressing uncertainty (don't know), use 'ob' (whether), not 'dass' (that).

A2-B1

'Dass' and 'ob' are both subordinate conjunctions, but they are used in different contexts.

'Dass' means 'that' and introduces a statement or fact that is certain.

'Ob' means 'whether' or 'if' and introduces an indirect question or uncertainty.

This lesson explains when to use each one correctly.

Explanation

'Dass' (that) introduces a statement or fact that is certain: 'Ich weiß, dass er kommt' (I know that he comes).

'Ob' (whether/if) introduces an indirect question or uncertainty: 'Ich frage, ob er kommt' (I ask whether he comes).

Use 'dass' when you're stating something you know or believe to be true.

Use 'ob' when you're asking about something uncertain or when the clause is a question.

Both send the verb to the end of the clause.

Dass vs Ob - Usage Guide

Conjunction	Meaning	Use	Example	Translation
dass	that	Certain statement/fact	Ich weiß, dass er kommt	I know that he comes
ob	whether/if	Uncertainty/question	Ich frage, ob er kommt	I ask whether he comes
dass	that	After verbs like wissen, glauben	Ich glaube, dass es wahr ist	I believe that it is true
ob	whether/if	After verbs like fragen, wissen nicht	Ich weiß nicht, ob er kommt	I don't know whether he comes

Examples

Ich weiß, dass er kommt.

I know that he comes. (certain)

Ich frage, ob er kommt.

I ask whether he comes. (uncertain)

Ich glaube, dass du recht hast.

I believe that you are right. (certain)

Ich weiß nicht, ob er kommt.

I don't know whether he comes. (uncertain)

Er sagt, dass er müde ist.

He says that he is tired. (certain statement)

Ich frage mich, ob das richtig ist.

I wonder whether that is correct. (uncertain)

Common Mistakes

✗

Ich frage, dass er kommt

✓

Ich frage, ob er kommt

When asking a question or expressing uncertainty, use 'ob' (whether), not 'dass' (that).

✗

Ich weiß, ob er kommt

✓

Ich weiß, dass er kommt

When stating something you know for certain, use 'dass' (that), not 'ob' (whether).

✗

Ich weiß nicht, dass er kommt

✓

Ich weiß nicht, ob er kommt

When expressing uncertainty (don't know), use 'ob' (whether), not 'dass' (that).

Practice Exercises

Test your understanding with interactive exercises. Practice makes perfect!

Start Exercises →

Subordinate Conjunctions Dass or Weil Als, Wenn, Wann or Ob

Frequently Asked Questions

How do I know which article to use?

German articles (der, die, das) depend on the gender of the noun. While there are some patterns, many nouns must be memorized. Practice and exposure to German will help you learn them naturally.

What's the difference between definite and indefinite articles?

Definite articles (der, die, das) mean 'the' and refer to specific things. Indefinite articles (ein, eine) mean 'a/an' and refer to non-specific things. Both must match the noun's gender: use 'ein' for masculine/neuter and 'eine' for feminine.

Are there rules for determining noun gender?

While there are some helpful patterns (e.g., words ending in -ung are usually feminine), there are many exceptions. The best approach is to learn nouns with their articles from the beginning.

What happens if I use the wrong article?

While using the wrong article is a common mistake, native speakers will usually still understand you. However, using the correct article is important for sounding natural and fluent in German.