What openings should I know as an 1300 Elo rated player ??

Your opening choice depends on your taste not your rating 

And as far opening is concerned you can even learn highly theoretical oepnings and complicated openings but the fact is if you memorise 20 move theory against grunfeld , you are even gonna see grunfeld very rarely 

But your knowledge of that opening and your study would help u at some point of  your career 

For eg :if you start learning 1.d4 from shankland it is sure you won't get that much theory but if you understood the moves, memorize the moves well that would help u sooner or later 

And as far your question concern take any opening (standard not dubious) learn it, understand it and do lot of tactics because most of the time under 2000 level you would have advantage in opening you would be winning or pawn up and then u suddenly miss a tactic and blunder a piece so dont do that 

Seeing your opponent's threat and neutralizing it and side by side improving your position is the key to success at that level

Every pawn can move to one of two possible positions and same with the knights. That gives your opponent 20 options. You will almost never encounter a rook pawn advancement, nor knights to the edge. This leaves 14 of your opponents options you could look into. You don't have to know them all. Learn c,d,e, & f file pawn advancements and knights inward openings. I would familiarize myself with these: Sicilian, french, QGD, caro kann, italian, spanish, Vienna, scotch, english, KID, Dutch, Alkekine, Benoni, Nimzo-indian, Grunfeld, Pirc, Modern, Kings Gambit, Evans gambit, Blackmar/diemer gambit, Catalan, & just in case, Scandinavian. Following opening principles (control the center, propagate your pieces & getting your King to a safe position) should keep you in the game against a, b, g, & h pawn openings. Learn tactics (forks, deflection, battery, discovery, bishop sacrifice, etc.). Know end game mating strategies and, of course, practice. 1400 should be a cake walk from here.

Well as a 1300 player one should only play openings like Sicilian when they are ready to devote their time into learning all the variations and preparing cuz openings like Grunfeld, Sicilian, English are either really difficult to play or have many variations. So first off for e4 I'd say you should have minimum 3 openings prepared against it. Which are 1e4-e5. e5 might seme like a very simple opening but it's like a basic people don't understand sometimes how important this opening is. 1e4-c6 karo and 1e4-c5 Sicilian only if u are ready to learn almost 20 variations if not try 1e4-e6 french. Well for the queens pawn learn queens gambit, at this level accepting it is the worst nightmare, and it's very easy to play against it (as an opening) cuz all the main opening such as Marshal Defence, slave, semi slave, queens gambit declined usually lead to the exact same opening. Also prepare Indian game against d4 i.e 1d4-nf6. But if you'r doing this you are either gonna end up in the Nimzo Indian or the Kings indian. And both openings require some prep so only play that if you are ready to devote time untill then the only good option to d4 is d5

By 1500 rating, I knew pretty much all the main openings by name and the first few moves. I only knew the openings I played slightly deeper, but most of my opening theory didn't pass move 10 and most openings I only knew about 5 moves deep or so around that time.

At 1300, I say you should be experimenting a little and learning what you like, but memorizing specific variations isn't too important unless it is the opening you choose to regularly play. I would pick an opening and stick with it though. For example, what to play against 1. e4? You mentioned Caro-Kann and Sicilian you knew, but these are two openings against 1. e4 and you can only choose one. I recommend picking the one you like most for now and using that opening consistently each time you are in this position.

@25

"what other opening should i learn ?"
++ None at all. You do not win or lose because of the opening, but because of tactical mistakes.
'forget about the openings and spend all that time on the endings' - Capablanca

I find this website really helpful for learning my openings

chessbook.com/?ref=Joshforthewin

it has a free plan but you can also upgrade for $48 a year its pretty good my tutor IM Brandon Clarke recommened it to me.

copy and paste the link into your browser if you want to try it out

I am not 1300 elo but my friend is and he told me that the best opening is the king gambit because most player don’t know how to play it

First grasp Opening Principles deeply.

Then as white always go for e4 !!!

E4 vs caro= exchange variation. Easy to remember as you need to play on the kingside.

E4 vs e5= scotch opening for its dynamics.

e4 vs c5= go for grand prix as it will teach you basics of attacking .

Other openings are less known at your level and less playable.

As black go for always Sicilian Accelerated Dragon and against d4 go for benko gambit.

How to study openings?

Do not focus on variations. Focus on the model games of each above openings based on that you will improve your overall understanding of the variation .

I hope my comment is useful.

Looks like OP has absolutely smashed their Elo rating since this post was made. Well done OP.

My coach said that don’t think with think think with chess with ever piece and don’t think of piece value think with what piece place is in like a pawn is about to be a queen then that pawn is worth not 1 point but 9 point or a knight fork make the knight worth 6 points so in a day in 900 elo my rating gone up to 1000 elo