Futur II for Assumptions

Think of Futur II as a time machine with a rearview mirror. You are standing in the present. You look back at a completed action. You use the "future" structure to express your current uncertainty about that past event. It sounds contradictory, right? Why use a future tense for the past? Think of it this way: you are projecting your guess forward until the truth is eventually revealed. You are saying, "By the time we find out the truth, it will have been like this." It adds a layer of probability. Usually, when you use Futur II for assumptions, you are about 80% sure. It is stronger than vielleicht (maybe) but softer than a direct statement of fact. It is the perfect middle ground for polite conversation and professional analysis.

1. 1Building this is like building a sandwich with three specific layers. You need to keep the order exact, or the whole thing falls apart.
2. 2Start with the present tense of werden. This is your "assumption engine." Conjugate it to match your subject (ich werde, du wirst, er/sie/es wird, etc.).
3. 3Put your main action in the Partizip II form (the "ge-" form). This goes near the end of the sentence.
4. 4Finish with the infinitive of either haben or sein. This depends on which auxiliary the verb usually takes in the perfect tense.
5. 5Structure: [Subject] + [werden] + [...] + [Partizip II] + [haben/sein].
6. 6Example: Er wird wohl den Bus verpasst haben. (He has probably missed the bus.)
7. 7Notice how haben stays in the infinitive at the very end. It never changes! This is the part that usually trips people up. Think of the infinitive as the anchor that holds the whole guess together.

Use this when you see evidence and want to draw a conclusion.

• Scenario: The Office. Your colleague’s desk is empty and her coat is gone. You say: Sie wird wohl schon nach Hause gegangen sein. (She has probably already gone home.)
• Scenario: A Late Friend. You are waiting at a restaurant. Your friend is 20 minutes late. You say: Er wird im Stau gestanden haben. (He must have been stuck in traffic.)
• Scenario: Job Interview. You are discussing a candidate who didn't mention a specific skill. You say: Er wird diese Erfahrung noch nicht gesammelt haben. (He likely hasn't gathered this experience yet.)
• Scenario: History. You are looking at an old building. You say: Die Architekten werden sich dabei etwas gedacht haben. (The architects must have had something in mind when doing that.)

Do not use Futur II if you are 100% certain of a fact. If you saw your friend get on the bus, just use the Perfekt: Er ist in den Bus eingestiegen. Using Futur II there would make you sound like you are doubting your own eyes. Also, avoid it for very simple, everyday things where a simple vielleicht is more natural. If you use it too much, you might sound like a narrator in a historical documentary. It is a powerful spice; don't dump the whole bottle into your soup. Finally, don't use it for future plans. That is Futur I. Futur II is for the "completed" feeling.

Even native speakers sometimes stumble here, so don't be too hard on yourself. The most common mistake is forgetting the infinitive at the end. People often say Er wird das gemacht and just stop. You need that haben or sein! Another mistake is choosing the wrong auxiliary. If the verb is a movement (like gehen), you must use sein. If it's a transitive verb (like machen), you must use haben.

• Wrong: Er wird wohl angekommen haben.
• Right: Er wird wohl angekommen sein.

Also, watch your word order in subordinate clauses. The conjugated werden moves to the very end, jumping over the infinitive. Ich glaube, dass er den Schlüssel vergessen haben wird. It feels like a linguistic gymnastics routine, but you'll get the hang of it.

You might wonder: "Why not just use müssen?"

• Er muss das vergessen haben. (He must have forgotten that.) -> This feels like a logical necessity. There is no other explanation.
• Er wird das wohl vergessen haben. (He probably forgot that.) -> This feels like a strong guess based on his character or the situation. It’s slightly more subjective.
• Er dürfte das vergessen haben. (He might have forgotten that.) -> This is weaker, maybe 50-60% certainty.

Futur II sits in that sweet spot of "I'm pretty sure I know what happened, even if I didn't see it."