White 27 vs Black 488
White starts from setup 27 (NQNRBKRB), Black from setup 488 (QBRNBKNR). In the encyclopedia since 2026-10-03: neither side starts better.
|cp| ≤ 5 at 400M · 800M · 1.6B · 4B nodes, two independent engines agree
How to play with different setups
White sets up the pieces by position No. 27, Black by position No. 488, mirrored on their own side; the pawns stand as usual.
Moves as usual: White starts; everything else follows the Chess960 rules.
The two setups
White: setup #27 N Q N R B K R B
King on the f-file, rooks on d, g, queen on the b-file; one bishop starts in a corner; the knights start away from the centre. Castling follows the Chess960 rule: king and rook end on the classical squares. In ordinary symmetric play setup 27 gives White +0.27 (Morozov Balance Index, 400M nodes).
Black: setup #488 Q B R N B K N R
King on the f-file, rooks on c, h, queen on the a-file; no 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 488 gives White +0.38 (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 56.
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 same corridor is required at every deeper budget (8 G, 16 G) at which the pair has been evaluated.
The shallow rungs agreed early: from 100 thousand to 128 million nodes the evaluation never left ±13 cp.
For comparison, in symmetric play setup 27 gives White +0.27 and setup 488 gives White +0.38: with both sides on the same rank the first move is worth something. In this pair Black's own setup absorbs that edge completely.
White is not forced into a single path: the best first move is g3, and 2 first moves are within 10 cp of it.
Along the engine's main line (30 moves) the largest swing was 36 cp (around move 14), ending at 0 cp — the position stays playable for both sides.
Engine self-play agrees: 10 games, White won 0, drawn 10, Black won 0 (White scored 50.0%).
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 | -2 | 1. g3 c5 2. c4 h5 3. h4 d6 4. Nc2 Bc6 |
| S1 | 500 000 | 19 | +2 | 1. g3 c5 2. c4 h5 3. Nc2 d6 4. d3 Bc6 |
| S2 | 2 000 000 | 25 | -4 | 1. g3 Nf6 2. c4 c5 3. Nc2 h5 4. Nb3 d6 |
| S3 | 8 000 000 | 28 | +13 | 1. c4 Nf6 2. g3 c5 3. d3 h5 4. Ncb3 h4 |
| S4 | 32 000 000 | 36 | -8 | 1. c4 c5 2. g3 d6 3. Nc2 Bc6 4. Bxc6 Nxc6 |
| S5 | 128 000 000 | 43 | -5 | 1. c4 c5 2. g3 d6 3. d3 Bc6 4. Bxc6 Nxc6 |
| S6 | 400 000 000 | 51 | 0 | 1. c4 c5 2. g3 d6 3. d3 Bc6 4. Bxc6 Nxc6 |
| S7 | 800 000 000 | 56 | 0 | 1. c4 c5 2. g3 d6 3. d3 Bc6 4. Bxc6 Nxc6 |
| S8 | 1 600 000 000 | 56 | 0 | 1. c4 c5 2. g3 d6 3. d3 Bc6 4. Bxc6 Nxc6 |
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 | 0 |
| 8 000 000 000 | not checked |
| 16 000 000 000 | not checked |
This pair stays within the ±5 cp corridor up to 4 000 000 000 nodes.
Independent engines, run on the same position:
- Berserk 14: -8
- Lc0 0.32.1: +5
Independent confirmations: 3 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 +30, Black +65, difference -35. 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, 10 draws, 0 Black wins, White scored 50.0%.
Best first moves
The 3 best first moves for White, searched together at 400 000 000 nodes.
| # | Eval, cp | Depth | Main line |
|---|---|---|---|
| 1 | +5 | 43 | 1. g3 c5 2. c4 d6 3. Nc2 Bc6 4. Bxc6 Nxc6 5. d3 b6 |
| 2 | +4 | 43 | 1. c4 c5 2. g3 d6 3. Nc2 Bc6 4. Bxc6 Nxc6 5. d3 b6 |
| 3 | -20 | 42 | 1. b3 c5 2. g3 d6 3. c4 Bc6 4. Bxc6 Nxc6 5. d3 Nf6 |
Main-line play-out
30 moves, 5 000 000 nodes per half-move. Largest |evaluation| 36 cp, mean 17.1 cp, final 0 cp.
| # | White | cp | Black | cp |
|---|---|---|---|---|
| 1 | c4 | +13 | Nf6 | +14 |
| 2 | g3 | +12 | c5 | +10 |
| 3 | Nc2 | +21 | a5 | +11 |
| 4 | b3 | +27 | h5 | +22 |
| 5 | d4 | +19 | cxd4 | +21 |
| 6 | Nxd4 | +23 | Qa6 | +32 |
| 7 | Qf5 | +22 | e5 | +14 |
| 8 | Nb5 | +30 | Ne6 | +27 |
| 9 | Nc3 | +26 | Nd4 | +32 |
| 10 | Qd3 | +29 | d6 | +26 |
| 11 | e3 | +30 | Ne6 | +32 |
| 12 | h4 | +27 | Nc5 | +27 |
| 13 | Qe2 | +25 | Bd7 | +28 |
| 14 | O-O | +34 | O-O | +36 |
| 15 | Nd3 | +28 | Bg4 | +35 |
| 16 | Nxc5 | +25 | Rxc5 | +18 |
| 17 | Qd3 | +25 | Bxd1 | +21 |
| 18 | Qxd1 | +22 | Ba7 | +21 |
| 19 | a4 | +28 | g6 | +19 |
| 20 | Nb5 | +16 | d5 | +20 |
| 21 | cxd5 | +16 | Rd8 | +16 |
| 22 | Bg2 | +12 | Rcxd5 | +10 |
| 23 | Bxd5 | +5 | Rxd5 | +9 |
| 24 | Qf3 | +11 | Bb8 | 0 |
| 25 | Bc3 | 0 | Rd7 | 0 |
| 26 | Rd1 | 0 | Qc6 | 0 |
| 27 | Qe2 | 0 | b6 | 0 |
| 28 | Rxd7 | 0 | Qxd7 | 0 |
| 29 | e4 | 0 | Qg4 | 0 |
| 30 | Qd3 | 0 | Nxe4 | 0 |
Engine self-play
10 games at 500 000 nodes per move: White won 0, drawn 10, Black won 0 — White scored 50.0%. Average length 44.0 moves.
Sample game 1 (1/2-1/2)
1. g3 Nf6 2. c4 c5 3. Nc2 a5 4. b3 Qa6 5. d4 cxd4 6. Nxd4 h5 7. Qf5 e5 8. Nb5 Ne6 9. Nc3 Nd4 10. Qd3 d6 11. e3 Ne6 12. h4 O-O 13. O-O Nc5 14. Qe2 Bd7 15. Nd3 b5 16. cxb5 Bxb5 17. Nxb5 Qxb5 18. Nf4 Qxe2 19. Nxe2 Nce4 20. Bf3 Rc2 21. Bxa5 g5 22. Rfe1 Rxa2 23. Ra1 Rb2 24. Reb1 Rxb1+ 25. Rxb1 g4 26. Bg2 d5 27. Nc3 Nxc3 28. Bxc3 Bd6 29. Rd1 Rc8 30. Be1 Kf8 31. Bxd5 Nxd5 32. Rxd5 Rc1 33. Rxd6 Rxe1+ 34. Kg2 Kg7 35. Rd5 Kf6 36. Rd8 Kg6 37. Rd6+ Kg7 38. Rd5 Kf6 39. Rd8 Kg6 40. Rg8+ Kh6 41. Re8 Rb1 42. Rxe5 Rxb3 43. e4 Rb4 44. Kf1 Ra4 45. Rf5 Rxe4 46. Rxf7 Kg6 47. Rd7 Re5 48. Kg2 Ra5 49. Rd3 Kf5 50. Rb3 Ra6 51. Rb2 Ra3 52. Rb5+ Kg6 53. Rg5+ Kh6 54. Rd5 Ra2 55. Kf1 Kg6 56. Rg5+ Kh6 57. Re5 Ra1+ 58. Kg2 Ra2 59. Kf1 Ra1+ 60. Re1 Ra2
Sample game 2 (1/2-1/2)
1. g3 h5 2. d4 a5 3. c4 Qa6 4. Qd3 d6 5. O-O Nf6 6. h4 b5 7. b3 O-O 8. Nc2 Ba7 9. Bc3 bxc4 10. bxc4 Bc6 11. d5 Bd7 12. c5 Bb5 13. Qd2 Bxc5 14. Nd3 Ba7 15. Ne3 Bd7 16. Nf4 Re8 17. Bf3 c6 18. Bxf6 exf6 19. dxc6 Nxc6 20. Ned5 Bg4 21. Nxh5 Bxh5 22. Bxh5 Re5 23. Bg4 f5 24. Bh5 Nd4 25. Nf4 Rc2 26. Qd3 Qc6 27. e3 Rc3 28. Qd2 Rc2 29. Qd3 Rc3 30. Qd2 Rc2
Play it in the CH960 app
Open this page on a phone with the CH960 app installed, or find pair 27 / 488 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): qbrnbknr/pppppppp/8/8/8/8/PPPPPPPP/NQNRBKRB w DGch - 0 1
Mirror twin: White 929 vs Black 573 — a different position (castling squares are fixed), not evaluated by the search.
Current place in the live balance rating: 153.