As if and as though

An impression, not a confirmed fact

As if and as though introduce a comparison. An impression is what you think or feel from what you notice. It is not necessarily a fact you have checked. The two expressions have similar meanings and can replace each other in these comparison patterns.

• The room looks as if someone has just left.
• The room looks as though someone has just left.

You may be right: perhaps someone has just left. Or you may be making a comparison without believing it is literally true. As if does not mean that the situation is definitely false, and as though does not mean it is definitely true.

• The empty station felt as if we were the last people in the city.

The speaker is describing a feeling, not reporting that everyone else has disappeared. Cambridge says as if is more common than as though; that does not make as though a different tense pattern or a guarantee of formality.

Build a clause after the comparison

A clause is a group of words with a verb and, in the full pattern here, its own subject. After as if or as though, put the subject before the verb, as in an ordinary statement. Do not use question word order.

• The motor sounds as if it needs oil.
• You seem as though you are waiting for someone.
• She carried the tray as if it weighed nothing.

The subject after as if can be different from the subject before it: the motor... it; the room... someone. Keep the subject when you are using this full-clause pattern. Shorter patterns are explained below.

After look, sound and feel

You can compare an appearance with look, a sound with sound, or an experience with feel. These verbs connect the person or thing to your impression.

A noun comparison has a different shape. Compare looks like a lake with looks as if it is a lake. A noun phrase is a noun with words that belong with it, such as a small lake. Like can come before that phrase; as if introduces the fuller idea with it is.

• The flooded field looks like a lake.
• The flooded field looks as if it is a lake.

A short description is another option: the field looks wet. Choose the structure that gives the detail you need. See As and like for like, as and other comparisons.

A situation that may be true

When you think the explanation is possible, choose a verb form that fits its time. You can use a present form for a state now, a continuous form for an activity in progress, or a perfect form for something earlier that matters now.

• The visitors look as if they need directions.
• The cat sounds as though it is trying to get out.
• The desk looks as if someone has moved it.

These are possible explanations, not proof. You could find out that the visitors know the way or that the desk has not moved. The grammar presents an impression.

A future prediction can use will after as if. This is a comparison clause, not the ordinary if-clause of a future condition.

• With that broken wheel, it looks as if we will need another trolley.

Do not take the rule for if in a sentence such as if the wheel breaks, we will stop and apply it to every as if comparison. See Zero and first conditionals: real conditions for that separate pattern.

Acting as if something were true

As if and as though can follow other verbs to compare a way of acting with an imagined situation.

• He guards his lunch as if it were a bag of gold.
• She waved at the empty window as though someone was watching.

When you want to stress that you do not believe an idea is true, you can use a past form with a present meaning. This is sometimes called an unreal past. The form shows distance from reality, not a past date.

• My cousin explains the route as if she knew every street, but she has never been there.
• He handles that wooden spoon as though it were made of glass.

Knew compares her way of speaking with having that knowledge now. It does not say that she knew the streets before. A present form can also occur in an imagined comparison; the past form is a way to stress the distance from reality, not a requirement after every as if.

Was and were in unreal comparisons

With I, he, she or it, were can replace was in an unreal comparison. This subjunctive were is a form used for an imagined situation. Collins records it in written English and very formal speech; Swan also gives were as a formal-style option.

• The child speaks as if she were the guide.
• The child speaks as if she was the guide.

Both can express the unreal comparison. Was is accepted in ordinary English; do not mark it wrong just because the child is not the guide. Were makes the unreal form visible, especially when the context could be unclear. With you, we and they, were is also the ordinary past form, so the spelling alone does not settle the meaning.

This were is not a plural agreement error after she. It belongs to the imagined comparison. See Unreal time: it's high time, would rather and as if and The second conditional: unreal situations now or in the future for related uses.

Past time and past perfect: read the context

A past form after as if can also belong to a story about the past. Do not decide that a comparison is unreal just because you see a past verb.

• At the workshop, Leo looked as if he understood the instructions.

Perhaps Leo really understood them. Or perhaps he only gave that impression. The sentence does not settle it. Compare now he looks as if he understands with then he looked as if he understood.

The past perfect, had plus a past participle such as left, can place something before a past impression. It can also be part of an unreal comparison about an earlier event. Context tells you whether the event really happened.

• The floor was wet. It looked as though someone had washed it before we arrived.
• She greeted me as if we had met before, but that was our first meeting.

In the first example, washing is a possible explanation for the wet floor. In the second, the friendly greeting is compared with an earlier meeting that did not happen. Had met is not, by itself, a signal that every past-perfect comparison is false.

The same caution applies to a vivid comparison such as a room looking as if a storm had passed through it. The speaker may be exaggerating its untidiness, not claiming there was a storm. Read the situation as well as the form.

Shorter comparisons

You can also use as if or as though without a full subject-and-finite-verb clause. A finite verb has tense or a modal such as can; to reach and reaching are non-finite forms. These shorter comparisons describe the same person or thing understood from the sentence.

• He raised his hand as if to ask a question.
• She bent closer as though listening for a reply.
• The visitors stood still as if in a photograph.

To ask suggests the action his movement seemed to prepare for; it does not say he actually asked. Listening describes what her movement seemed to show. In a photograph is a phrase beginning with a preposition. These are not unfinished versions of the full pattern: they are shorter comparison structures.

Cambridge also gives non-finite clauses and preposition phrases after both as if and as though, without assigning a level to each.

Informal like and a separate reply

In informal English, like can introduce a clause with the meaning of as if. Cambridge notes that this use is not always accepted in formal contexts. As if or as though is a safer choice when your writing needs to avoid that objection.

• It sounds like the neighbours are moving furniture.
• It sounds as if the neighbours are moving furniture.

Do not confuse like plus a comparison clause with feel like plus an -ing form to say what you want to do. That is a different pattern; see Verb + -ing: enjoy, stop, avoid.

As if can also stand alone as a very informal reply showing disbelief. This is a separate conversational use, not the full comparison-clause pattern.

• A: Will you finish all that painting in ten minutes? B: As if.

B means that the suggestion is not believable. Cambridge labels the reply informal and BBC calls it very informal. It is not a neutral answer to use in every conversation.

What comes next

See As and like for noun comparisons and roles, Unreal time: it's high time, would rather and as if and Wish and if only: wishes about now, the past and the future for unreal forms, The past perfect simple for earlier past events, and The second conditional: unreal situations now or in the future for imagined conditions.