IF I WERE vs IF I WAS :
their difference and use explained

WERE :
‘Were’ is the subjunctive mood of the verb ‘be’.
We use were when talking about something that is not true, something hypothetical or imaginery, or to express a wish.
We use ‘if I were’ instead of ‘if I was’ to introduce an imaginery, hypothetical or unlikely situtation.
(The same applies to other pronouns: ‘he’, ‘she’, ‘it’...)
- If I were rich (imaginery situation), I would travel around the world.
(I am not rich. I’m imagining being rich and what I would do in that case.)
- I wish I were rich. (wish)
I am not rich but I would like to have a lot of money.

WERE : More examples of the use of 'were' in imaginery/hypothetical situations

• If I were you, I would book a flight now.
• If I were you, I would accept the offer.
• If I were your father, I would not allow you to do that.
• If it were possible for human beings to fly, I would be very happy.
• If that lady were to change seats, we could all sit down.

WAS :
'Was' is the standard past tense of the verb 'be'.
We use ‘was’ to talk about real events or real possibilities, things that possibly or probably happened in the past.
If I was not clear, I will explain it again.
(This is a real possibility. It is possible that I was not clear.)

WAS : More examples of the use of 'was' for facts and real possibilities

• If I was the cause of the argument, I’m really sorry. (I could be the cause.)
• I thought I gave you the right information. If I was wrong, I’m sorry. (It is possible that I was wrong.)
• If I was inattentive, it was because the topic was boring. (I was probably inattentive.)
• If it wasn't for the life jacket, I would have drowned. (There was a lifejacket .)
• If this was a mistake, it was the only one he made. (A mistake is possible.)
• If it wasn’t so far away,I would walk to work. (The long distance is a fact)

Sentences where ‘when’ can replace ‘if’ :
During my childhood I used to go to the beach every day.
- If/when I was alone, I would spend the time swimming.
- If/when I was with other children, I would play with them.