White 243 vs Black 103
White starts from setup 243 (BNRKQNRB), Black from setup 103 (QNBRNKRB). 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 #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).
Black: setup #103 Q N B R N K R B
King on the f-file, rooks on d, g, queen on the a-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 103 gives White +0.17 (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 60.
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 -13 and +21 cp before settling — a reminder that quick engine checks overstate imbalances, and why the ladder goes deep.
For comparison, in symmetric play setup 243 gives White +0.27 and setup 103 gives White +0.17: 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 e4; the alternatives are slightly weaker but keep the game level.
Along the engine's main line (30 moves) the largest swing was 34 cp (around move 9), ending at 0 cp — the position stays playable for both sides.
Engine self-play agrees: 10 games, White won 1, drawn 9, Black won 0 (White scored 55.0%).
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 | +21 | 1. c4 g6 2. Nc3 b6 3. b3 Bb7 4. Ne3 c6 |
| S1 | 500 000 | 18 | +3 | 1. c4 b6 2. b3 d5 3. d3 dxc4 4. bxc4 Qc6 |
| S2 | 2 000 000 | 20 | +17 | 1. b3 d5 2. g4 a5 3. O-O-O O-O 4. d4 g6 |
| S3 | 8 000 000 | 25 | +10 | 1. g4 d5 2. b3 a5 3. O-O-O c5 4. a4 b5 |
| S4 | 32 000 000 | 31 | -13 | 1. g4 d5 2. b3 a5 3. d3 a4 4. b4 Qa7 |
| S5 | 128 000 000 | 45 | 0 | 1. e4 g6 2. Nc3 a5 3. g4 Qa7 4. b3 c6 |
| S6 | 400 000 000 | 51 | 0 | 1. e4 g6 2. Nc3 a5 3. g4 c6 4. b3 Qa7 |
| S7 | 800 000 000 | 56 | 0 | 1. e4 g6 2. Nc3 a5 3. g4 c6 4. b3 Qa7 |
| S8 | 1 600 000 000 | 60 | 0 | 1. e4 g6 2. Nc3 a5 3. g4 c6 4. b3 Qa7 |
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: -6
- Lc0 0.32.1: +3
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 +116, Black +58, difference +58. A balanced pair needs White's setup to be weaker by about the price of the first move.
Extended self-play: 10 games, 1 White wins, 9 draws, 0 Black wins, White scored 55.0%.
Best first moves
The 3 best first moves for White, searched together at 400 000 000 nodes.
| # | Eval, cp | Depth | Main line |
|---|---|---|---|
| 1 | 0 | 41 | 1. e4 g6 2. Nc3 a5 3. b3 Qa7 4. g4 c6 5. Qe3 Bd4 |
| 2 | -18 | 41 | 1. c4 g6 2. Nc3 c6 3. g4 Na6 4. f4 Qb8 5. Qf2 d5 |
| 3 | -29 | 41 | 1. b3 d5 |
Main-line play-out
30 moves, 5 000 000 nodes per half-move. Largest |evaluation| 34 cp, mean 7.7 cp, final 0 cp.
| # | White | cp | Black | cp |
|---|---|---|---|---|
| 1 | g4 | +10 | d5 | -11 |
| 2 | b3 | -28 | a5 | -17 |
| 3 | d3 | -21 | Qa7 | -24 |
| 4 | Nbd2 | -19 | Na6 | 0 |
| 5 | c4 | 0 | d4 | +9 |
| 6 | Ne4 | 0 | Qb6 | 0 |
| 7 | c5 | +10 | Qb5 | 0 |
| 8 | Nfd2 | 0 | g6 | -17 |
| 9 | Nc4 | -29 | a4 | -34 |
| 10 | Qa5 | -32 | Qxa5 | -27 |
| 11 | Nxa5 | -19 | axb3 | -16 |
| 12 | axb3 | -19 | c6 | -15 |
| 13 | b4 | -16 | Nxb4 | -18 |
| 14 | Rb1 | -14 | Nd5 | -13 |
| 15 | Nxb7 | -7 | Bxb7 | -10 |
| 16 | Rxb7 | -3 | Nec7 | -6 |
| 17 | Kc2 | -3 | O-O | -8 |
| 18 | h4 | -5 | Ne6 | 0 |
| 19 | Bb2 | 0 | Ra8 | -2 |
| 20 | Ra1 | -1 | Rxa1 | 0 |
| 21 | Bxa1 | 0 | Ra8 | 0 |
| 22 | Bb2 | 0 | Be5 | 0 |
| 23 | Rb3 | 0 | Kf8 | 0 |
| 24 | Ra3 | 0 | Rb8 | 0 |
| 25 | Rb3 | 0 | Nb4+ | 0 |
| 26 | Kd1 | 0 | f5 | 0 |
| 27 | gxf5 | 0 | gxf5 | 0 |
| 28 | Ba3 | 0 | Ra8 | 0 |
| 29 | Ng5 | 0 | Nxc5 | 0 |
| 30 | Rxb4 | 0 | Rxa3 | 0 |
Engine self-play
10 games at 500 000 nodes per move: White won 1, drawn 9, Black won 0 — White scored 55.0%. Average length 40.2 moves.
Sample game 1 (1/2-1/2)
1. g4 g6 2. c4 Na6 3. Nc3 c6 4. f4 Qb8 5. Qf2 d5 6. cxd5 Nb4 7. b3 cxd5 8. a3 Nc6 9. Nxd5 Bxa1 10. Rxa1 Be6 11. Nfe3 Nc7 12. Nxc7 Bxb3+ 13. Ke1 Qxc7 14. Bxc6 Qxc6 15. Rg3 b6 16. Nf1 Be6 17. Rc3 Qa4 18. f5 Bd7 19. fxg6 Rxg6 20. h3 Rc8 21. Rf3 Be8 22. Ng3 Rcc6 23. Rd1 Rge6 24. d4 Rf6 25. Nh5 Rxf3 26. Qxf3 Qc2 27. Rd3 Qb1+ 28. Rd1 Qc2 29. Rd3 Qb1+ 30. Rd1
Sample game 2 (1/2-1/2)
1. b3 d5 2. g4 a5 3. d3 c6 4. Nbd2 a4 5. c4 d4 6. a3 axb3 7. Nxb3 Qxa3 8. Nxd4 Na6 9. Nc2 Qd6 10. Bd4 g6 11. Bb6 Nec7 12. Qa5 O-O 13. Rb1 Be6 14. Nce3 Bd4 15. Bxd4 Qxd4 16. Nd2 Qf4 17. Nf3 Bxc4 18. Rxb7 Ne6 19. O-O Nac5 20. Rb2 Bd5 21. Qb4 Qf6 22. Nxd5 cxd5 23. d4 Ne4 24. e3 N6g5 25. Ne5 Nh3+ 26. Kg2 Nhxf2 27. Rbxf2 Nxf2 28. Qb2 Qe6 29. Kxf2 f6 30. Nd3 Qxg4 31. Nf4 e5 32. Bxd5+ Kh8 33. dxe5 g5 34. exf6 gxf4 35. f7+ Qg7 36. Qxg7+ Kxg7 37. e4 Rxd5 38. exd5 Kf6 39. Rd1 Kxf7 40. Kf3 Ke7
Play it in the CH960 app
Open this page on a phone with the CH960 app installed, or find pair 243 / 103 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): qnbrnkrb/pppppppp/8/8/8/8/PPPPPPPP/BNRKQNRB w CGdg - 0 1
Mirror twin (the same position mirrored): White 611 vs Black 850.