Trouble calculating deep lines

Calculation is a mandatory skill as a player of chess, and at certain positions, it is crucial to be able to calculate lines as deep as 10.
The problem I have is that I am unable to go further than maybe a few lines such as 3, because I do not know what the opponent's next move should be, I know what my next move should be but I do not know what the opponent's next hypothetical move should be, at let's say depth 3 or 7.
The calculation then becomes invalid or useless when the calculation is played out and the opponent makes a move that counters your entire plan.

How do you know to calculate not only your move, but also your opponent's ?

Calculation is important but calculating 10 moves ahead is not. There are good players who rely on intuition and prep instead of doing 10 move calculation in game.

Everyone has their own quirks. Some can calculate much better than others but doesn't always mean they are better than their competitors.

I would calculate enough to a point where it looks I am not blundering. Sometimes that's just a 2 move calculation. Sometimes 7 moves.

If I am playing classical and I have plenty of time, I will calculate as much as I can but faster time controls, 2 or 3 moves is probably good enough for me. I would rely more on prep and intuition.

Remember the adage long analysis, wrong analysis and analysis paralysis.

It's an old, apocryphal story, and I don't even recall who said it. But what the hey..

"Grandmaster, how many moves ahead can you see?"
"Only one. The best"

GMs do calculate, sometimes to great depth. When they have to. When they can, they rely on their experience, intuition and judgement.

@verylate said in #3:

It's an old, apocryphal story, and I don't even recall who said it. ...
https://www.chesshistory.com/winter/extra/movesahead.html

"... Most of the time you can find a good move - if not the best move - with a low level of calculation. How low? Two and a half moves into the future. ..." - GM Andrew Soltis (2010)
I guess an example would be the position after 1 d4 Nf6 2 Nd2 e5 3 dxe5 Ng4 4 h3, when Black perceives that 4...Ne3 can be played because of 5 fxe3 Qh4+ 6 g3 Qxg3#.

Don't worry about 10.
Practice longer time controls at depth 3 then 4 then 5.
If you can get to 5 with 20+ or 30+ you can play just fine.
The super GMs might calculate 30 moves once or twice during big games. Worry about it at super GM level. 5 is fine. Sometimes 6 or 7 if many exchanges. Grunfeld kinda needs 12. Don't play Grunfeld lol or Najdorf.

@schizoplayer said in #1:

The problem I have is that I am unable to go further than maybe a few lines such as 3, because I do not know what the opponent's next move should be, I know what my next move should be but I do not know what the opponent's next hypothetical move should be, at let's say depth 3 or 7.
The calculation then becomes invalid or useless when the calculation is played out and the opponent makes a move that counters your entire plan.

How do you know to calculate not only your move, but also your opponent's ?
Part of the calculation skill is evaluating the position you've calculated. That seems intuitive, but in practice we tend to only look at what we're doing and not consider what happens when our opponent doesn't cooperate. It's a skill that's only improved with practice, and I"m afraid shorter time controls don't lend themselves to learning it.

CM Azel Chua has calculation courses on Chessable which are pure gold. They are not free, but well worth the small expense ($40 US). There's a beginner one and a more advanced one. Go there and search Calculation: A complete guide for tournament players. I don't 'recall the name of the beginner course but I suspect it's also great. If you currently don't have a good structured way of calculating, that'll definitely give you one.

You can also search Youtube and see interviews he did talking about chess. You'll quickly see he's got a great insight for what blocks improvement.

Another skill which is hugely important is visualization. I like practicing that on listudy.org doing blind tactics, though I don't do it often enough. That really helps point out when you're ignoring an opponent response because like you said, that mistake makes all subsequent calculation invalid.

As a side note, in a recent C-Squared podcast, Fabiano discussed a won game that he failed to convert due to a missed evaluation of a position. That position in a R/Ps v R/Ps endgame was after he'd calculated what appeared to be 20+ moves deep. He recalled all that without a board and could clearly see how his evaluation had been incorrect. I don't think I ever heard a player recall a line that long calculated OTB before, and it was only one nuance he'd not even overlooked, just misjudged. That nuance allowed a draw. It's incredible how far out there, top players are.

@kindaspongey said in #5:

I guess an example would be the position after 1 d4 Nf6 2 Nd2 e5 3 dxe5 Ng4 4 h3, when Black perceives that 4...Ne3 can be played because of 5 fxe3 Qh4+ 6 g3 Qxg3#.

Where did you take this variation from? 2. Nd2 is not a move, I wouldn't consider 2...e5, I wouldn't even look at 4. h3... These moves make no sense to me, for either side!

Calculation is useful in positions with tension because there are forcing continuations. In a position with no tension maneuvering becomes more important and designing plans. Deep calculation is more useful in endgames, in middlegames its more common with short bursts to keep track of positions 2-3 moves ahead.