A conditional sentence has two parts: a condition (wenn...) and a result. German makes a clear grammatical difference between REAL conditions (things that can genuinely happen) and UNREAL/hypothetical ones (imaginary situations) — and Konjunktiv II is the signal that tells you which one you're in.
Types you should know
reale Bedingung
real condition — present tense
irreale Bedingung
unreal/hypothetical condition — Konjunktiv II
See it in action
Type
German
English
Real
Wenn ich Zeit habe, komme ich mit.
If I have time, I'll come along. (genuinely possible)
Unreal
Wenn ich Zeit hätte, würde ich mitkommen.
If I had time, I would come along. (I don't have time)
Memory trick: Real condition = ordinary present tense in both halves. Unreal condition = Konjunktiv II in both halves (hätte...würde). Never mix a real 'wenn' clause with a würde-result — that's the #1 learner error.
⚠ Common mistake: Don't write "Wenn ich Zeit habe, würde ich mitkommen" — mixing real present tense with an unreal würde-result is inconsistent; match the two halves.
🎯 Quick check
Which sentence describes a truly hypothetical (unreal) situation?