--- title: "Search depth in chess" url: "https://georgelichess.com/glossary/search-depth.md" canonical_url: "https://georgelichess.com/glossary/search-depth" last_updated: "2026-11-07" type: "reference" summary: "Search depth is how many moves ahead an engine has looked in a position, counted in half-moves called plies. Glance at the depth before you rely on a score." related: ["https://georgelichess.com/glossary/principal-variation.md", "https://georgelichess.com/glossary/alpha-beta-pruning.md", "https://georgelichess.com/glossary/minimax.md", "https://georgelichess.com/glossary/chess-engine.md", "https://georgelichess.com/glossary/evaluation.md", "https://georgelichess.com/glossary/engine-analysis.md", "https://georgelichess.com/glossary/category/computer-chess.md", "https://georgelichess.com/glossary.md"] --- # Search depth in chess > **For AI agents:** the complete index of GeorgeLiChess pages is [llms.txt](https://georgelichess.com/llms.txt). Every page is also served as markdown at its URL plus .md. Search depth is how many moves ahead an engine has looked in a position, counted in half-moves called plies. Glance at the depth before you rely on a score. Search depth is how many moves ahead an engine has looked in a position, counted in half-moves called plies, and deeper searches generally give more reliable evaluations and moves. In practice: glance at the depth before you rely on a score. Search depth tells you how far into the future an [engine](https://georgelichess.com/glossary/chess-engine.md) has calculated. It is counted in plies, where one ply is a single move by one side, so a depth of twenty means ten moves by each player. Analysis boards display the depth beside the [evaluation](https://georgelichess.com/glossary/evaluation.md), and it rises as the engine thinks for longer. Greater depth usually means a better result, because the engine has seen more consequences of each move. Early in a search the top move can change as the engine finds a [tactic](https://georgelichess.com/glossary/tactic.md) that was beyond its horizon. Once the depth has grown and the [best move](https://georgelichess.com/glossary/best-move.md) stays steady, you can trust the suggestion more. As a student, glance at the depth before you rely on a score. A quick glance at depth 10 may miss a deep [combination](https://georgelichess.com/glossary/combination.md), while depth 30 or more on a quiet position is quite dependable. Engines also extend important lines, such as checks and [captures](https://georgelichess.com/glossary/capture.md), further than the stated depth, so the number is a rough guide and not an exact limit. Give the engine a few seconds on critical positions, and do not draw firm conclusions from a very shallow reading. Also called: depth. It sits close to [Principal variation](https://georgelichess.com/glossary/principal-variation.md). The principal variation is the line of best play for both sides that an engine has found, shown as a sequence of moves and tied to the evaluation it reports. A neighboring idea is [Minimax](https://georgelichess.com/glossary/minimax.md). Minimax is a decision method in which one side tries to maximize the evaluation while the opponent tries to minimize it, forming the basis of how traditional chess engines choose moves. Compare it with [Alpha-beta pruning](https://georgelichess.com/glossary/alpha-beta-pruning.md). Alpha-beta pruning is a search technique that skips branches of the move tree that cannot change the minimax result, letting engines look much deeper using the same amount of computing time. Computer terms such as "Search depth" are most useful next to a coach who reads your games with you, which is how a [first lesson](https://georgelichess.com/book/first-lesson.md) with George Li works. ## Related terms - [Principal variation](https://georgelichess.com/glossary/principal-variation.md) - [Alpha-beta pruning](https://georgelichess.com/glossary/alpha-beta-pruning.md) - [Minimax](https://georgelichess.com/glossary/minimax.md) - [Chess engine](https://georgelichess.com/glossary/chess-engine.md) - [Evaluation](https://georgelichess.com/glossary/evaluation.md) - [Engine analysis](https://georgelichess.com/glossary/engine-analysis.md) ## Guides that go further - [How to choose a chess coach](https://georgelichess.com/how-to-choose-a-chess-coach.md): What to decide first, the questions to ask, what a first lesson should show and the red flags to avoid. - [How much does chess coaching cost?](https://georgelichess.com/chess-coaching-cost.md): Published rates for private, group and subscription chess coaching, with the source and the date of each. - [The first lesson](https://georgelichess.com/book/first-lesson.md): A game review, a read on your level and a written study plan from George Li. [Book your first lesson](https://georgelichess.com/book.md) and George Li reviews your games and builds a study plan around them. Questions about lessons: write to hello@georgelichess.com. ## Related - [Principal variation in chess](https://georgelichess.com/glossary/principal-variation.md) - [Alpha-beta pruning in chess](https://georgelichess.com/glossary/alpha-beta-pruning.md) - [Minimax in chess](https://georgelichess.com/glossary/minimax.md) - [Chess engine](https://georgelichess.com/glossary/chess-engine.md) - [Evaluation in chess](https://georgelichess.com/glossary/evaluation.md) - [Engine analysis in chess](https://georgelichess.com/glossary/engine-analysis.md) - [Chess terms: Computer chess and analysis](https://georgelichess.com/glossary/category/computer-chess.md) - [Chess terms glossary: plain definitions](https://georgelichess.com/glossary.md)