White 247 vs Black 255
White starts from setup 247 (NRBKQNRB), Black from setup 255 (NRKQNRBB). 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 #247 N R B K Q N R B
King on the d-file, rooks on b, g, queen on the e-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 247 gives White +0.18 (Morozov Balance Index, 400M nodes).
Black: setup #255 N R K Q N R B B
King on the c-file, rooks on b, f, queen on the d-file; one bishop starts in a corner; the knights start away from the centre. The king already stands on a castled square, so one of the castlings moves only the rook. In ordinary symmetric play setup 255 gives White +0.16 (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 55.
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 agreed early: from 100 thousand to 128 million nodes the evaluation never left ±8 cp.
For comparison, in symmetric play setup 247 gives White +0.18 and setup 255 gives White +0.16: 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 d3, and 3 first moves are within 10 cp of it.
Along the engine's main line (20 moves) the evaluation stayed within ±29 cp the whole way: the balance holds as the pieces come out, not only on move one.
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 | -6 | 1. d3 f5 2. Nb3 c6 3. Bd2 g6 4. g3 Bg7 |
| S1 | 500 000 | 18 | -2 | 1. Nb3 f5 2. d4 c6 3. Bd2 g6 4. Bh6 Bg7 |
| S2 | 2 000 000 | 22 | +8 | 1. Nb3 f5 2. d4 c6 3. Bf4 Nac7 4. O-O-O a5 |
| S3 | 8 000 000 | 27 | 0 | 1. Nb3 f5 2. d4 d6 3. g4 fxg4 4. Rxg4 Qd7 |
| S4 | 32 000 000 | 32 | -4 | 1. Nb3 f5 2. d3 c6 3. g3 Nd6 4. f4 b6 |
| S5 | 128 000 000 | 42 | 0 | 1. Nb3 f5 2. d3 c6 3. g3 Nd6 4. e4 fxe4 |
| S6 | 400 000 000 | 45 | 0 | 1. d3 f5 2. Nb3 Nd6 3. f4 g6 4. g4 a5 |
| S7 | 800 000 000 | 54 | 0 | 1. d3 f5 2. Nb3 Nd6 3. f4 g6 4. g4 a5 |
| S8 | 1 600 000 000 | 55 | 0 | 1. d3 f5 2. Nb3 Nd6 3. f4 g6 4. g4 fxg4 |
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: +1
- 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 +58, Black +28, difference +30. 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 | +3 | 43 | 1. d3 f5 2. Nb3 c6 3. Bd2 e5 4. g3 g6 5. e4 fxe4 |
| 2 | 0 | 43 | 1. Nb3 f5 2. d3 c6 3. Bf4 Nac7 4. g3 Nd6 5. Be5 b6 |
| 3 | 0 | 42 | 1. g3 f5 |
Main-line play-out
20 moves, 5 000 000 nodes per half-move. Largest |evaluation| 29 cp, mean 2.2 cp, final 0 cp.
| # | White | cp | Black | cp |
|---|---|---|---|---|
| 1 | Nb3 | +3 | f5 | -10 |
| 2 | g4 | -14 | f4 | -13 |
| 3 | d4 | -20 | Nb6 | -29 |
| 4 | e3 | 0 | g5 | 0 |
| 5 | h4 | 0 | Nd6 | 0 |
| 6 | hxg5 | 0 | e5 | 0 |
| 7 | dxe5 | 0 | Bxe5 | 0 |
| 8 | Nc5 | 0 | Qxg5 | 0 |
| 9 | Nd3 | 0 | Re8 | 0 |
| 10 | b3 | 0 | Bd5 | 0 |
| 11 | e4 | 0 | Bc6 | 0 |
| 12 | a4 | 0 | Qg7 | 0 |
| 13 | Nxe5 | 0 | Qxe5 | 0 |
| 14 | Bb2 | 0 | Qc5 | 0 |
| 15 | O-O-O | 0 | Nxe4 | 0 |
| 16 | a5 | 0 | Nc4 | 0 |
| 17 | bxc4 | 0 | O-O-O | 0 |
| 18 | Bd4 | 0 | Qa3+ | 0 |
| 19 | Bb2 | 0 | Qc5 | 0 |
| 20 | Bd4 | 0 | Qa3+ | 0 |
| 21 | Bb2 | 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 29.4 moves.
Sample game 1 (1/2-1/2)
1. Nb3 f5 2. d4 d6 3. g3 Nb6 4. Qa5 Qd7 5. Nfd2 g6 6. O-O Nf6 7. Re1 Bd5 8. Bxd5 Nbxd5 9. Nf3 Nb6 10. Bh6 Rg8 11. Red1 Qa4 12. c3 Kd7 13. Ne5+ Ke6 14. Nf3 Rgc8 15. Qxa4 Nxa4 16. c4 Kd7 17. Be3 Ne4 18. Ne1 c5 19. f3 cxd4 20. Bxd4 Bxd4+ 21. Rxd4 Nf6 22. Nd3 Ke8 23. Nb4 b6 24. Nc2 Nd7 25. Ne3 Ne5 26. Kf2 a6 27. h3 Kd7 28. g4 fxg4 29. hxg4 Rh8 30. Re4 Rbc8 31. f4 Nc6 32. Nd5 e6 33. Nf6+ Ke7 34. Nd5+ Kd7 35. Nf6+ Ke7 36. Nd5+
Sample game 2 (1/2-1/2)
1. d3 f5 2. Be3 b6 3. c4 e5 4. g3 Qe7 5. Nc2 c6 6. f4 exf4 7. Bxf4 Nac7 8. Qc3 b5 9. Nd2 bxc4 10. dxc4 Bf7 11. Be5 d6 12. Bd4 c5 13. Qe3 Qxe3 14. Bxe3 Nf6 15. O-O a5 16. Rfd1 g5 17. Bxg5 Ne6 18. Bxf6 Bxf6 19. b3 Bg6 20. e3 Bc3 21. Rbc1 Bb2 22. Rb1 Bc3 23. Na3 f4 24. gxf4 Bb4 25. Ne4 Bxa3 26. Rxd6 Re8 27. Rc6+ Kd7 28. Nf6+ Ke7 29. Nd5+ Kd7 30. Nf6+ Ke7 31. Nd5+ Kd7
Play it in the CH960 app
Open this page on a phone with the CH960 app installed, or find pair 247 / 255 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): nrkqnrbb/pppppppp/8/8/8/8/PPPPPPPP/NRBKQNRB w BGbf - 0 1
Mirror twin (the same position mirrored): White 610 vs Black 608.
Current place in the live balance rating: 175.