White 226 vs Black 243
White starts from setup 226 (BNRQKBNR), Black from setup 243 (BNRKQNRB). In the encyclopedia since 2026-10-03: neither side starts better.
|cp| ≤ 5 at 400M · 800M · 1.6B · 4B nodes, two independent engines agree
The two setups
White: setup #226 B N R Q K B N R
King on the e-file, rooks on c, h, queen on the d-file; one bishop starts in a corner; the knights start on central files. Castling follows the Chess960 rule: king and rook end on the classical squares. In ordinary symmetric play setup 226 gives White +0.06 (Morozov Balance Index, 400M nodes).
Black: setup #243 B N R K Q N R B
King on the d-file, rooks on c, g, queen on the e-file; one bishop starts in a corner; the knights start on central files. Castling follows the Chess960 rule: king and rook end on the classical squares. In ordinary symmetric play setup 243 gives White +0.27 (Morozov Balance Index, 400M nodes).
Why the pair is balanced
At the deepest rungs (400M, 800M, 1.6B nodes) the evaluation is exactly 0.00 each time, reaching search depth 58.
Admission rule: |cp| ≤ 5 at four budgets up to 4 billion nodes, no one-sided drift along the ladder, and confirmation by two independent engines — Berserk and Lc0 — each below its own median on symmetric positions.
The shallow rungs wandered between -22 and +4 cp before settling — a reminder that quick engine checks overstate imbalances, and why the ladder goes deep.
For comparison, in symmetric play setup 226 gives White +0.06 and setup 243 gives White +0.27: with both sides on the same rank the first move is worth something. In this pair Black's own setup absorbs that edge completely.
The engine's first choice for White is d4; the alternatives are slightly weaker but keep the game level.
Along the engine's main line (30 moves) the largest swing was 101 cp (around move 10), ending at -30 cp — the position stays playable for both sides.
Engine self-play agrees: 10 games, White won 0, drawn 9, Black won 1 (White scored 45.0%).
Verification ladder
Nine independent searches of the starting position, each with a larger node budget. Evaluation in centipawns from White's point of view.
| Stage | Nodes | Depth | Eval, cp | Main line |
|---|---|---|---|---|
| S0 | 100 000 | 13 | +4 | 1. b4 e5 2. Nf3 g5 3. d4 exd4 4. Bxd4 Bxd4 |
| S1 | 500 000 | 20 | +2 | 1. b4 e5 2. h4 d6 3. c4 b6 4. e3 g6 |
| S2 | 2 000 000 | 22 | -19 | 1. b4 e5 2. e3 b6 3. h4 g6 4. c4 d6 |
| S3 | 8 000 000 | 27 | -22 | 1. b4 e5 2. h4 d5 3. d4 exd4 4. Nf3 b6 |
| S4 | 32 000 000 | 33 | -7 | 1. d4 g5 2. h4 gxh4 3. Rxh4 b6 4. g3 O-O-O |
| S5 | 128 000 000 | 39 | 0 | 1. d4 g5 2. h4 gxh4 3. Rxh4 b6 4. Rh2 d5 |
| S6 | 400 000 000 | 46 | 0 | 1. d4 g5 2. h4 gxh4 3. Rxh4 b6 4. Nf3 e5 |
| S7 | 800 000 000 | 55 | 0 | 1. d4 g5 2. h4 gxh4 3. Rxh4 b6 4. Nf3 e5 |
| S8 | 1 600 000 000 | 58 | 0 | 1. d4 g5 2. h4 gxh4 3. Rxh4 b6 4. Nf3 e5 |
Deep verification
The search ladder reaches 1.6 billion nodes; admission needs a 4-billion rung and two further engines on top of that. Beyond even that, every pair was re-checked at budgets up to ten times larger and in thousands of self-play games. This section shows what each check returned for this pair.
| Nodes | Eval, cp |
|---|---|
| 4 000 000 000 | not checked |
| 8 000 000 000 | not checked |
| 16 000 000 000 | not checked |
This pair held exactly 0.00 up to 1 600 000 000 nodes.
Independent engines, run on the same position:
- Berserk 14: -5
- Lc0 0.32.1: -4
Independent confirmations: 2 of 3. An engine counts as confirming when its reading of the pair is closer to equality than its own reading of a typical symmetric Chess960 position (+10 for Berserk, +18 for Lc0). Where only one engine confirms, the pair is balanced according to that engine alone, and this page says so.
Own weight of each setup, measured against the classical array: White +49, Black +116, difference -67. A balanced pair needs White's setup to be weaker by about the price of the first move.
Extended self-play: 10 games, 0 White wins, 9 draws, 1 Black wins, White scored 45.0%.
Best first moves
The 3 best first moves for White, searched together at 400 000 000 nodes.
| # | Eval, cp | Depth | Main line |
|---|---|---|---|
| 1 | -6 | 40 | 1. d4 g5 2. h4 g4 3. e3 b6 4. Ne2 e6 5. c4 c5 |
| 2 | -33 | 40 | 1. h4 e5 2. b4 d5 3. g3 O-O-O 4. Bg2 g6 5. c4 dxc4 |
| 3 | -46 | 40 | 1. b3 e5 |
Main-line play-out
30 moves, 5 000 000 nodes per half-move. Largest |evaluation| 101 cp, mean 66.4 cp, final -30 cp.
| # | White | cp | Black | cp |
|---|---|---|---|---|
| 1 | b4 | -23 | e5 | -32 |
| 2 | e3 | -34 | b6 | -52 |
| 3 | Ne2 | -50 | g5 | -54 |
| 4 | d4 | -47 | Nc6 | -49 |
| 5 | d5 | -43 | Nxb4 | -50 |
| 6 | Nbc3 | -60 | c6 | -58 |
| 7 | d6 | -54 | Ng6 | -54 |
| 8 | e4 | -69 | c5 | -86 |
| 9 | Nb5 | -95 | Nc6 | -95 |
| 10 | Nec3 | -101 | Nd4 | -95 |
| 11 | Nxa7 | -101 | Rb8 | -95 |
| 12 | Nab5 | -94 | Qf8 | -62 |
| 13 | Bc4 | -60 | Nh4 | -52 |
| 14 | Rg1 | -51 | Bc6 | -45 |
| 15 | a4 | -52 | f5 | -31 |
| 16 | Bxg8 | -37 | Qxg8 | -90 |
| 17 | Na7 | -75 | Ba8 | -67 |
| 18 | Nd5 | -62 | fxe4 | -71 |
| 19 | Ne3 | -73 | Ng6 | -56 |
| 20 | g3 | -71 | Nf3+ | -84 |
| 21 | Kf1 | -90 | g4 | -89 |
| 22 | a5 | -96 | Bf6 | -85 |
| 23 | Nb5 | -79 | Bg5 | -86 |
| 24 | Nc7 | -90 | Bc6 | -84 |
| 25 | Rb1 | -76 | Qf8 | -81 |
| 26 | c4 | -82 | Bxe3 | -83 |
| 27 | fxe3 | -71 | Nd4+ | -73 |
| 28 | Kg2 | -71 | Qf3+ | -59 |
| 29 | Qxf3 | -63 | exf3+ | -35 |
| 30 | Kf2 | -31 | Nf5 | -30 |
Engine self-play
10 games at 500 000 nodes per move: White won 0, drawn 9, Black won 1 — White scored 45.0%. Average length 45.6 moves.
Sample game 1 (1/2-1/2)
1. d4 g5 2. e3 Ng6 3. c4 b6 4. b4 f5 5. h4 Nxh4 6. Rh2 Qf7 7. Nc3 e6 8. b5 Bf6 9. Qa4 d6 10. g3 Ng6 11. Qxa7 Nd7 12. O-O-O O-O 13. Qa3 e5 14. Kb1 f4 15. Bh3 exd4 16. exd4 Bg7 17. Qb3 Nf6 18. Bf5 c5 19. bxc6 Bxc6 20. Nh3 h6 21. gxf4 Nh4 22. Bxc8 Rxc8 23. fxg5 Ng4 24. gxh6 Nxh2 25. hxg7 Qf5+ 26. Kc1 Ng2 27. Rh1 Qxh3 28. c5+ d5 29. Nxd5 Qxb3 30. Ne7+ Kf7 31. axb3 Kxe7 32. Rxh2 Bd5 33. Kd2 Kf7 34. Rh5 Rd8 35. f3 Kxg7 36. Rg5+ Kf7 37. c6 Bxc6 38. Rxg2 Rd5 39. f4 Ra5 40. Rg1 Rf5 41. Rf1 Bd5 42. Kc3 Rh5 43. Kb4 Ke6 44. Re1+ Kd6 45. Bc3 Rh3 46. Rf1 Ke6 47. f5+ Kf6 48. Re1 Rf3 49. Re8 Rxf5 50. Rb8 Rh5 51. Rxb6+ Kf5 52. Rb5 Ke4 53. Ka3
Sample game 2 (1/2-1/2)
1. b4 d6 2. e3 b6 3. d4 g5 4. c4 Ng6 5. Nc3 e6 6. Nb5 Nh4 7. Ne2 Nc6 8. d5 Bxa1 9. dxc6 Be5 10. Nxa7 Bxc6 11. Nxc8 Kxc8 12. Nd4 Nxg2+ 13. Bxg2 Bxg2 14. Rg1 Bb7 15. c5 bxc5 16. bxc5 dxc5 17. Rxc5 Bxh2 18. Rgxg5 Bd6 19. Rb5 Rxg5 20. Rxg5 Bd5 21. Qd3 Qa4 22. f3 Kd7 23. a3 h6 24. Rg7 Ke7 25. Qg6 Qa5+ 26. Kf1 Bc4+ 27. Ne2 e5 28. Qc2 Qd5 29. Kf2 Bd3 30. Nc3 Qxf3+ 31. Kxf3 Bxc2 32. Rg2 e4+ 33. Kg4 Bb3 34. Kf5 Bxa3 35. Rh2 Bb4 36. Nxe4 Be6+ 37. Ke5 f6+ 38. Kd4 Ba5 39. Rxh6 Bb6+ 40. Kc3 Ba5+ 41. Kb2 Bb6 42. Rh7+ Kd8 43. Kc3 Bxe3 44. Nxf6 c6 45. Rh8+ Ke7 46. Kd3 Bc1 47. Rh1 Ba3 48. Ne4 Bd5 49. Rh7+ Ke6 50. Rh6+ Ke5 51. Rh5+ Ke6 52. Kd4 Bxe4 53. Kxe4 Bf8 54. Kd4 Kd7 55. Rh7+ Ke6
Play it in the CH960 app
Open this page on a phone with the CH960 app installed, or find pair 226 / 243 in the app's encyclopedia, then choose how to play.
- Local game — two players on one device, with a clock.
- With a mentor — a clearly labelled training bot with hints, at your level.
- Challenge a friend — an online game by link; both players get the same pair, colours swap on rematch.
Play this pair against the computer, right here Play a friend
FEN (Shredder, castling rights by rook files): bnrkqnrb/pppppppp/8/8/8/8/PPPPPPPP/BNRQKBNR w CHcg - 0 1
Mirror twin (the same position mirrored): White 631 vs Black 611.