"If I Were" — the Subjunctive Were
The 'if I were' construction is the single most recognizable surviving piece of the English subjunctive, and it's also the one most commonly 'corrected' into 'if I was' by speakers who've never been told the two forms are doing genuinely different jobs — one marks something hypothetical or contrary to fact, the other marks an ordinary past-tense statement.
The core rule: hypothetical and contrary-to-fact statements
When a sentence describes something that isn't true, or that's purely hypothetical, the subjunctive 'were' replaces 'was' for every subject, including I, he, she, and it: If I were you, I'd apologize. If she were taller, she could reach the shelf. He acts as if he were in charge. In each case, the statement is explicitly not describing reality — I am not you, she isn't taller, he isn't actually in charge — which is exactly the signal the subjunctive 'were' is built to send.
When 'was' is actually correct instead
Ordinary past-tense 'was' is correct when the situation being described is a real, factual past state rather than a hypothetical one: If I was tired yesterday, it was because I stayed up late (this describes an actual, uncertain-but-possible past fact, not a contrary-to-fact hypothetical). The test is whether the if-clause could, in principle, turn out to be true or false as a statement about reality — if so, 'was' fits; if the sentence is explicitly imagining something false or purely hypothetical, 'were' is called for.
Wishes trigger the same subjunctive pattern
The identical 'were' pattern shows up after 'wish,' for the same underlying reason — a wish is inherently describing something that isn't currently true: I wish I were taller. She wishes she were finished by now. Because 'wish' always implies the wished-for state doesn't currently hold, 'was' never fits grammatically correct formal usage here, even though 'I wish I was' is extremely common in casual speech.
'As if' and 'as though' clauses
The same subjunctive 'were' appears after 'as if' and 'as though' when the comparison being drawn is explicitly false or exaggerated: He talks as if he were an expert (implying he isn't). She looked at me as though I were speaking a foreign language (implying I wasn't). When the 'as if' comparison could plausibly be literally true, though, 'was' is acceptable: She acted as if she was tired (she may genuinely have been tired) versus she acted as if she were a queen (she plainly is not one).
Why 'if I was' is so common despite being technically nonstandard here
Because 'was' is the ordinary past tense of 'be' for I/he/she/it, and because the subjunctive has otherwise nearly vanished from spoken English, many speakers regularize 'if I were' to 'if I was' by analogy with normal past-tense agreement, without any loss of communicative clarity — a listener understands the hypothetical either way. This is a textbook case of a language's regular pattern (matching 'was' to singular subjects) pulling against a shrinking irregular survivor (the subjunctive 'were'), and in casual speech the regular pattern is winning, even though formal written English still expects 'were.'
The famous song lyric test case
Beyoncé's 'If I Were a Boy' is frequently cited by grammar writers as a rare example of pop music actually using the grammatically 'correct' subjunctive form where a less careful lyric might have used 'was' — it's become something of an informal teaching example precisely because it's a widely known, easily quoted instance of the construction used exactly as formal grammar prescribes it, unlike much casual and song-lyric English, which regularly substitutes 'was.'
Does this rule apply to plural subjects too?
Not in the same way — 'were' is already the standard past tense for we/you/they regardless of subjunctive mood, so the hypothetical-versus-real distinction that matters for I/he/she/it simply doesn't create a visible fork in the road for plural subjects: If they were here, they'd help (this sentence is unambiguous either way, since 'were' is simply the only past-tense form plural subjects ever take).
Is insisting on 'were' ever actually wrong?
Using 'were' in a context where the statement is genuinely a real, uncertain past fact rather than a hypothetical one is itself a (much rarer) overcorrection error: 'If I were late yesterday, I apologize' should usually be 'If I was late yesterday, I apologize,' since this describes an actual, possibly-true past state rather than something explicitly contrary to fact — a reminder that the choice tracks meaning, not just formality.
Subjunctive were in formal writing versus fiction dialogue
Formal essays, academic prose, and edited journalism consistently maintain 'were' in hypothetical if-clauses, treating 'if I was' in the same slot as a noticeable register slip. Fiction dialogue, by contrast, often deliberately uses 'if I was' for characters written in a more casual, naturalistic voice, since real spoken English overwhelmingly favors 'was' here regardless of a speaker's education level — a novelist matching how people actually talk will often choose 'was' on purpose, not by error, precisely because rigid subjunctive 'were' can sound unnaturally formal in quoted speech.
How this construction is taught versus how it's tested
Standardized tests and style guides still treat the hypothetical 'were' as a fixed, testable rule, which is part of why it remains one of the more commonly drilled subjunctive points in school grammar instruction, even as its use in unscripted speech continues to erode. This gap between what's taught as correct and what's actually said aloud mirrors the broader pattern seen with whom — a grammatical form propped up by formal writing convention well past the point where most speakers reliably produce it without conscious effort.
Common overcorrection: inserting 'were' where 'was' is factually correct
Because some writers absorb 'if I were' as a blanket formal-sounding upgrade rather than a meaning-based choice, 'were' sometimes gets inserted into ordinary factual past statements where it doesn't belong: 'I wondered if she were coming to the party' misapplies the hypothetical form to what is, in context, simply an open factual question about the future, not a contrary-to-fact hypothetical — 'was' (or 'is,' depending on tense) is what this sentence actually wants, since the writer isn't asserting that she isn't coming.
A closing test to apply confidently
The reliable diagnostic across every case above is to ask directly: is this statement asserting something untrue, imagined, or wished-for, as opposed to something that might genuinely be or have been the case? If the answer is 'asserting something untrue or imagined,' use were regardless of subject. If the answer is 'describing something that might really be true,' was is correct for I/he/she/it, exactly as ordinary past tense would predict.
Subjunctive were after 'suppose' and 'imagine'
Verbs that invite the listener into a hypothetical scenario, like suppose and imagine, often pair naturally with the subjunctive were in the clause that follows: Suppose she were elected president — what would change? Imagine if he were in your position. As with other hypothetical triggers, 'was' is common informally in exactly this slot, but the formal subjunctive were remains the construction most style guides prefer for clearly counterfactual scenarios like these.
How this pattern is likely to keep changing
Linguists tracking long-term shifts in English mood marking generally expect the subjunctive were to keep receding in casual spoken use, following the same trajectory as whom and the mandative subjunctive covered elsewhere — surviving longest in formal writing and set phrases, while ordinary speech continues regularizing toward the simpler, more broadly applicable 'was.' Whether this eventually reaches formal written English too is unclear, but for now the distinction remains actively taught and actively enforced in edited prose, which is reason enough to keep it in any serious writer's toolkit.
Frequently asked questions
Is 'if I was' ever correct?
Yes, when describing a real, possibly-true past situation rather than a hypothetical or contrary-to-fact one: 'If I was rude earlier, I'm sorry' is standard, because it's not asserting the statement is false — it's leaving open that it might genuinely have happened.
Why does 'were' replace 'was' only in hypotheticals?
Because 'were' in this context is a surviving fragment of the English subjunctive mood, a grammatical form specifically reserved for hypothetical, wished-for, or contrary-to-fact statements, distinct from ordinary indicative past tense, which simply reports real past events.
Is 'if I were you' a fixed expression or a live grammar rule?
Both — it's common enough to function almost like a fixed phrase in speech, but it's also a live, productive application of the broader subjunctive rule, which is why the same 'were' pattern extends naturally to other subjects and other hypothetical if-clauses beyond just this one famous phrase.
Does 'wish' always require 'were' instead of 'was'?
In formal usage, yes, for singular subjects like I, he, she, and it, since a wish inherently describes something not currently true. Casual speech very often uses 'was' here instead, but formal written English still expects 'were.'
Is 'as if it were yesterday' correct?
Yes — this common idiom is a textbook subjunctive were, marking a comparison to something not literally true (it is not, in fact, yesterday), which is exactly the contrary-to-fact meaning the subjunctive were is reserved for.