Is — where will I have left my keys? — grammatical?

Question

Where will I have left my keys?

Is this structure grammatical and used?

I'm trying to say something like

where did I leave my keys?

but using will.

Answer 1

You're actually adding both "will" and "have" in your proposed sentence. So, there are three options:

1. Where will I have left my keys?
2. Where will I leave my keys?
3. Where have I left my keys?

They're all grammatical but it would significantly more likely that you would say either 2 or 3 than 1. So, let's look at 2 and 3 first:

Where will I leave my keys?

One might say this in a situation like this:

I left my keys at the office yesterday and at home the day before... where will I leave my keys today, I wonder?

In this case, the speaker is implying that it's inevitable that they will leave their keys somewhere after having left them somewhere the two days prior.

Where have I left my keys?

This is equivalent to "where did I leave my keys" but using have. In the US, it's probably less common that the "did" version but still perfectly fine.

Now, as to version 1... This would be an extremely unlikely construction. You could probably find a tortured example that will work but it would take some trying. If you really want to use "will" use version 2.

Answer 2

Commonly you will see this two ways:

1- Where are my keys? -- blaming the keys for being lost.

2- Where have I left my keys? -- blaming yourself for losing the keys.

Using the Future Perfect, without any context, suggests rhetorical devices - monologue or conversational dialogue.

Answer 3

For what it's worth:

Where would I leave my keys? is probably what you have in mind.

Suppose you've got a date, or there's an opera performance at the local theatre you just can't miss (Giacomo Puccini's Tosca, to pick an opus at random). You've already called all your friends, asking them not to bother you till at least midnight with their petty concerns and stupid questions. You've had your snack. You've showered, shaved, brushed your teeth, etc. You've put on your best underwear, shirt, socks, suit, and shoes. You've brushed your hair. You've made sure you've got your wallet. Now you've got to pick up your keys. Where are the keys? No keys. They're supposed to be on the phone stand by the front door. Nope. They're not there. You panic. You check the living room: the bookshelf; the TV stand; the piano. Nothing. You rush into the bedroom. The night table. The dresser. The window sill. Nothing. You look at your watch. You're not late yet. So you decide to approach this whole thing rationally. You draw a glass of water, drink it, and sit down by the piano. You strike a pose - you now resemble Rodin's thinker. You're sitting like this:

And you ask yourself:

"Hmm. Now where would I put my keys?"

Images start flashing through your mind: the piano; the book shelf; the bathroom sink; the phone stand; the left-hand pocket of your stylish overcoat ...

The left-hand pocket of your stylish overcoat! Of course!

You rush to the closet. You fling open the door. You check the left-hand pocket of your stylish overcoat, and then the right-hand pocket. And then the inside pocket. Nothing.

You go back to the piano and resume thinking. But it's a different question you have to ask yourself now:

Where would I leave my keys?

Where, indeed? The library? The pool? Your mistress' place? The cafe you had lunch at? Where would a red-blooded, moderately temperamental person like yourself leave his keys?

And now, finally, it dawns on you: of course. At your best friend's house last night. You were having some beers, watching a game, etc. Damn.

So you stand up, shake your head in wonderment at the world's idiotic social set up, and reach into your pocket. Because that's where your phone is. You've got to call your friend and tell him to look for your keys. You reach for your phone. In your pocket. Whoa. You realize your keys are in your pocket! Wow.

I hope this helps.

Answer 4

Where will I have left my keys?

Where did I leave my keys?

Both the sentences are correct grammatically, but they are in different tenses. The former is in the future perfect, whereas the latter is in the past simple. So they convey different meanings.

You use the future perfect (Will have + past participle) for something that is expected or planned to be over before a time of reference in the future. On the other hand, you use the past simple for something that was over in the past. Look at the following sentences to understand the difference:

Let's say it's five o'clock now. You can say "I will have finished my work by seven o'clock** (future perfect).

I finished my work at three o'clock (past simple).

As the OP is referring to something happened recently in the past, he can say "Where did I leave my keys?" or "Where have I left my keys?".

Answer 5

Yes, it is grammatical, but, as others have pointed out, it seems a bit forced in your example.  Constructions of the form

(subject) (have) (verb)ed

are called “perfect” tenses; “will have (verb)ed” is future perfect.  As Khan says, the perfect tenses are used when you refer to two different times in one sentence; your sentence doesn’t do that.  A somewhat “tortured” construction that makes this work is

If I will need to go somewhere urgently in the middle of the night, I wonder, where will I have left my keys?

Although,

1. “If I will need …” seems awkward.  When the sentence states a future time (assuming that “in the middle of the night” is obviously in the future, from context), it might be more natural to say “If I need …”.

2. Since this sentence is about going somewhere urgently, the fact that you left your keys somewhere is of secondary importance.  It might be more natural to say “… where will my keys be?”

A somewhat less forced example: Your boss tells you to go to a meeting at 2PM at a place that is unfamiliar to you; it is a three hours’ drive away.  You might ask,

If I’m there at 2PM, where will I have eaten lunch?

Note, again, the idiomatic use of present tense with a future time: “If I am there [this afternoon] …” ≅ “If I need to go somewhere in the middle of the night …”.