@1
Play 15|10, thanks to increment you have time to win a won position or draw a drawn position.
Losing on time in winning positions.

Your opponents are doing better time management. He who finds the moves quickest has the advantage. You might be "winning", but if it took you too long to figure out how to be "winning", you're not really "winning". I have the same problem.
Play faster.
1g1yy. I appreciate you responding to my post. Would you mind rereading the post as I believe you misunderstood what I was asking.

I think I understood it completely. We have a similar problem. It takes us too long to come up with accurate moves. If we don't spend the time, our moves are not accurate and we're losing. If we do spend the time, our position is fine but we run out of time.
The clock is a big part of the game. Hence the reason high rated players offer a handicap to lower rated players like 5 minute vs 2 minute, or such. I've seen Daniel Naroditsky play 30 seconds vs someone else with 3 minutes. Getting in time trouble is just part of the game. Everyone does it.
If you want to get better at that sort of thing, try Puzzle Rush. But take it seriously.
Hi, tygxc. Thanks for responding to my post. I have considered playing with increment but feel like that is more like avoiding my issue than solving it. Though maybe by playing with increment I can get better at endgames and apply that to not increment games. Thanks for the suggestion.
Recommend working on time management, move selection and end game play.
Play 15-30 min controls to remove the "time pressure" element the move selection process. The tendency for cautious play, over thinking or deep analysis is not best suited for speed games. Start slow, build experience and confidence, then try faster controls.
Limit of 6 games per day to allow for analysis and study. Make notes during play for review later. Analyze each game after its completion before next game. Use self-analysis then engine. Replay each move, why was it made, better move, missed hanging pieces, etc. Compare with engine. This will identify weaknesses.
Understand concept of reducing opponent attacking capabilities via exchanges when you have a strong advantage. Don't delay exchanges without good reason.
Work on end game principles of pawn promotion, mating with Q+N, R+R; narrow the board to confine K. Averbakh's Chess Endings or any End Game book works.
Time was managed poorly: Opening 10 moves took 50 sec, too long. 10% of your time spent on simple moves. Make these moves confidently and quickly (1-2 sec each). Move 12 took 37sec on g4; Bg5 was better. Move 12 was not critical. Compare this to moves 43-76, which took 55 sec. You lost the game by move 12.
Move 36 RxR was a poor choice and not under time pressure. If you cannot track 3 pieces, you will not do well in chess. Develop a mental premove checklist such as king safety, checks, captures, threats and improving piece activity. Going thru this list, you have a R & B hanging; NxR is only move. Move 76. Qa8??; you had M2 and perhaps a win before time expired. Puzzles, puzzle rush and game analysis will help with this.
Some moves appeared to go counter to the flow of the game; however, you had a good game and winning position! While it worked in this game, it may not against higher-rated players. Game analysis will help.
Apologies for the long post.

To convert a position you need to figure out how you will win it. This is best done by analyzing the game afterwards, and not finding BETTER moves, but more PRACTICAL moves, to make the position easier.
There was a lot of good responses earlier, so I will mainly focus on how to play faster, not better. After all, everyone gets in time pressure.
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A simple example: Let's say you are white here with low time (<10 seconds). You panic and start checking your opponent with your rook repeatedly while trying to checkmate them, but you end up losing on time (hypothetically).
After the game, you may want to spend some time trying to see if there was something easier. There was. Move the rook next to your king, protecting it - and then premove the pawn up the board, and then ladder mate the black king. You'd need a bit of mouse speed but it is very easy to do.
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Here is a game I played. Notice how in the endgame, my opponent knew that to win he needed to push his pawn, and focused only on pushing his pawn. Although it wasn't immediately winning, I ended up blundering with both sides under 20 seconds.
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Some things that might help:
1. drilling endgames. There are drills on chess.com - with the ones you can do, try to do them as fast as you can. When I was around 1800 online, I worked through rook endgames a lot simply because they appear very, very often in blitz and rapid - and it helps.
2. Post game analysis: if you lose a winning game on time, look it over and try to see if you can find a simpler winning plan. Use the engine for assistance if you need to, but it is important that you develop the skill of finding the path of least resistance.
3. Watching GM blitz games: They are very good at converting positions with under 15 seconds. It is bewildering, and sometimes fascinating, to watch them win such games.
@7
"playing with increment but feel like that is more like avoiding my issue than solving it."
++ Originally chess was without clocks. People played so slowly, that first hour glasses and then clocks were necessary. Then speed chess emerged and with it flagging. Flagging is no part of pure chess: drawing / winning / losing on the board as originally intended. In that sense flagging distracts from pure chess. Then increment was invented to return speed chess to the pure form.
If you insist on playing without increment, then these apply:
If you lose on the board with time left on your clock, then you played too fast.
Identify your mistake and see if thinking longer could have avoided it.
If you lose on the clock with a good position on the board, then you played too slowly.
Identify the move that took you most time and see if you could have found it faster.
There is also a paradox.
Sometimes thinking longer allows you to find a faster win.
By playing faster and missing the fast win, the game may get longer and you may lose on time.
You have to understand why in a completely winning position you go from 50 seconds to 14 seconds in three moves. Your oponent had no threat and you just had to play one move. Then you have no time left, you panic and miss opportunies (it happens to all of us).

The clock is a part of the game, if your opponent makes suboptimal moves but makes them fast and imposes practical problems to you that you can't punish, than it's not THAT BAD of a move.... But there are a few things that can be done:
Play longer time formats with increments as was mentioned.
Play some blitz to train yourself to move faster, you will lose a lot but when you go back to rapid you should be able to play faster (not necessarily better tho, which is why I would not recommend)
Learn how to convert winning positions. Not going to dwell much on that but there's plenty of material online on how to that, like bizmark mentioned the very best engine move is not always the most practical, but to summon it up avoid your opponents counterplay and try to trade down as much material as you can. Also, in the case you mentioned, if you have a bunch of pieces, make sure they're defended so your opponent can't capture them.
With time you'll learn how to convert winning endgames faster.
Good Luck

One thing I noticed is you spend a lot of time thinking in the early to mid game about what the best move could be. I noticed while watching your game you spent a lot of time thinking only to then make a simple, easier move (like moves 12 and 16). It looks like you searched all your pieces for a good move, didn’t find one, and then played a simple move because you were still unsure and wanted to play safe. Another possibility is that you were searching all of your pieces and then evaluating the position for the best possible option.
Either way, you spend a lot of time calculating as opposed to the simpler solution, which is pattern recognition.
Puzzles are probably your best bet for that, as their quick little bits to hammer a specific theme. Rushes are great as their quick bursts of energy to find whatever the best move is.
Another thing you could do is find what you’re willing to trade and what you’d wanna hold on to. Maybe you find you have more success when you hold on to your bishops over your knights, or maybe you have a stronger mid game if there aren’t queens to worry about (I quite like it that way, but maybe you don’t). Those kind of quirks help you speed up your mid game, as a lot of the thinking is done for you.
Endgames are something where knowing the theory is how you finish. In your example game, you gave their king a ton of room to maneuver, which made them harder to mate. Instead, after taking the rook, you could’ve gone Qe5, and then premoved promoting and laddering the king.
I think you’re really close to what you’re looking for, you just need to keep pushing.
Good luck
Hi, tygxc. Thanks for responding to my post. I have considered playing with increment but feel like that is more like avoiding my issue than solving it. Though maybe by playing with increment I can get better at endgames and apply that to not increment games. Thanks for the suggestion.
Why not start with very small increments? Say, 10|2 perhaps? Once you are able to master it, you can slowly find a good time to remove increments later on.
Recently, I keep losing on time in winning positions. But I don't understand how to rectify this. Take this game for example: https://www.chess.com/analysis/game/live/56385639385?tab=analysis (draw by timeout). This is a 10:0 game, which I have decided to start playing because of the problem I'm having being way more common in 5:0.
This is a typical game for me: I slowly gain an advantage though the opening and middle game with about equal time as my opponent. But in the endgame I end up running out of time.
I feel like if I don't spend enough time thinking about my moves I will through away the win because a vast majority of the time my opponents will punish any inaccuracy I make. This is demonstrated in the example game at move 36. I believe this to be a material tracking problem. If your opponent only has one piece to play with but you have 4, you have to make sure you don't misplace 4 times as many pieces as him.
So my question is, how do I train my self to not have to spend so much time on my moves, whilst also not throwing away my advantage? I keep playing thinking to myself that this is something that improves with experience but I have played thousands of games (on old accounts and lichess) and I still keep losing winning games on time.
(If there is an equivalent forum post somewhere that you know of that gives a good answer to my question, please link it here.)