How Strong Is The Engine?

The Ladder

What each difficulty level is worth on the CCRL Blitz scale, measured rather than guessed:

Levels 1–4 play with deliberate limits and suit players from beginners to strong club players, about 400 points apart. Level 5 is the engine at full strength, with no handicaps — which is why the last step is the big one.

How It Was Measured

1,750 games of classic chess against Stash, an open-source engine whose versions are rated on the CCRL Blitz list — a public rating list for chess programs. Every level played one to three Stash versions close to its own strength: 100 games against each, and level 5 400 games each against Stash 25.0 (rated 2933) and Stash 27.0 (rated 3049).

• 60 seconds per game plus 0.6 seconds per move, one core and 64 MB of hash for each engine.
• Every game started from a book of balanced openings, each played twice with the colours swapped.
• The games were run by cutechess-cli on an Intel Xeon E5-2680 v4 (2.4 GHz, turbo off).
• Ratings from the CCRL Blitz list of 17 October 2026.

Every game is public: download all games (PGN).

Phone Or Desktop

• Levels 1–4 are identical on any device. They stop at a fixed search depth rather than when the clock runs out, so even a slow phone reaches it in time and chooses the same move as a desktop.
• Level 5 depends on the processor. It thinks for a set time on every move, so the faster the processor, the deeper it calculates and the stronger it plays. On a phone level 5 is usually weaker than in the table — noticeably on older and budget models, hardly at all on new flagships. Our slowest test phone, a Nokia 6.1, calculates about 5× slower on one core than the test computer.

Even on the slowest phone, level 5 is far stronger than any human player.

Several Cores

Modern processors have several cores. With Multi-threaded Engine turned on in the settings, Maharajah thinks on several cores at once and plays stronger; the more cores, the bigger the gain. It only matters at level 5 — levels 1–4 already reach their depth on one core.

On the test computer, level 5 on 4 cores scored 64% against Stash 27.0, where one core scored 40% — roughly 3150 instead of 2995. On the Nokia 6.1, four cores calculate almost four times as fast as one.

The cost is faster battery drain and a warmer phone during long games. If battery life matters more, turn the switch off.

What The Numbers Do Not Say

• CCRL is a scale for chess programs, not people, so it cannot be compared directly with a FIDE rating. Treat the numbers as a guide to picking a level, not as a rating you can compare with a tournament certificate.
• They cover classic chess. The Maharajah variant, with its compound pieces, is a different problem and was not part of this measurement.
• The ladder is the engine with its neural network, which both the app and the board on this site play with. How it works is on how the engine works.

Credits

The reference opponent was Stash by Morgan Houppin and contributors, licensed under the GPLv3, with ratings from the CCRL team. Stash was used only as a measuring tool on a developer machine. It is not part of Maharajah, is not included in any build of the app, and does not run on our servers — every engine move you see in a game comes from our own engine.