White 49 vs Black 103
White starts from setup 49 (BNNBRQKR), 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 #49 B N N B R Q K R
King on the g-file, rooks on e, h, queen on the f-file; one bishop starts in a corner; the knights start on central files. The king already stands on a castled square, so one of the castlings moves only the rook. In ordinary symmetric play setup 49 gives White +0.26 (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, 3.2B nodes) the evaluation is exactly 0.00 each time, reaching search depth 63.
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 ±14 cp.
For comparison, in symmetric play setup 49 gives White +0.26 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 b3; the alternatives are slightly weaker but keep the game level.
Along the engine's main line (30 moves) the largest swing was 46 cp (around move 16), ending at +16 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 | 12 | +5 | 1. b3 d5 2. c4 b6 3. d4 c5 4. dxc5 g6 |
| S1 | 500 000 | 20 | +3 | 1. b4 d5 2. e3 a5 3. b5 c6 4. Qd3 O-O |
| S2 | 2 000 000 | 22 | 0 | 1. b4 d5 2. e3 a5 3. b5 c6 4. Qd3 Nd6 |
| S3 | 8 000 000 | 28 | +14 | 1. b3 d5 2. e4 dxe4 3. f3 O-O 4. fxe4 c5 |
| S4 | 32 000 000 | 34 | +11 | 1. b3 d5 2. e4 dxe4 3. f3 a5 4. Qf2 exf3 |
| S5 | 128 000 000 | 41 | 0 | 1. b3 d5 2. e4 dxe4 3. f3 exf3 4. Bxf3 a5 |
| S6 | 400 000 000 | 53 | 0 | 1. b3 d5 2. e4 dxe4 3. f3 exf3 4. Bxf3 Nd6 |
| S7 | 800 000 000 | 58 | 0 | 1. b3 d5 2. e4 dxe4 3. f3 exf3 4. Bxf3 Nd6 |
| S8 | 1 600 000 000 | 60 | 0 | 1. b3 d5 2. e4 dxe4 3. f3 exf3 4. Bxf3 Nd6 |
| S9 | 3 200 000 000 | 63 | 0 | 1. b3 d5 2. e4 dxe4 3. f3 exf3 4. Bxf3 Nd6 |
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: +2
- 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 +96, Black +58, difference +38. 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 | +11 | 42 | 1. b3 d5 2. e4 dxe4 3. f3 exf3 4. Bxf3 a5 5. Qf2 Qa6 |
| 2 | -9 | 41 | 1. e3 d5 2. b3 c5 3. f4 b6 4. Bf3 Bb7 5. Qe2 Nd6 |
| 3 | -13 | 41 | 1. b4 d5 2. h4 b6 3. Nb3 Na6 4. Bc3 c5 5. bxc5 Nxc5 |
Main-line play-out
30 moves, 5 000 000 nodes per half-move. Largest |evaluation| 46 cp, mean 24.2 cp, final +16 cp.
| # | White | cp | Black | cp |
|---|---|---|---|---|
| 1 | b3 | +7 | d5 | +15 |
| 2 | e4 | +1 | dxe4 | +15 |
| 3 | f3 | +7 | O-O | +13 |
| 4 | fxe4 | +19 | c5 | +18 |
| 5 | e5 | +27 | Nc6 | +21 |
| 6 | h4 | +13 | Qb8 | +17 |
| 7 | Nd3 | +34 | b5 | +41 |
| 8 | Na3 | +31 | c4 | +41 |
| 9 | bxc4 | +44 | b4 | +43 |
| 10 | Qf3 | +36 | Qb7 | +38 |
| 11 | Nb1 | +43 | Qa6 | +40 |
| 12 | c3 | +34 | bxc3 | +34 |
| 13 | Bxc3 | +38 | g6 | +28 |
| 14 | h5 | +26 | Bf5 | +32 |
| 15 | hxg6 | +41 | Bxg6 | +38 |
| 16 | Nf4 | +33 | Qb6+ | +46 |
| 17 | Kh2 | +36 | Bxb1 | +31 |
| 18 | Ba4 | +19 | Nd4 | +18 |
| 19 | Qg4+ | +22 | Bg6 | +25 |
| 20 | Nd5 | +21 | Rxd5 | +17 |
| 21 | cxd5 | +22 | Nb5 | +24 |
| 22 | Ba1 | +18 | Nbc7 | +8 |
| 23 | Bb3 | +14 | Qb5 | +15 |
| 24 | Qd4 | +20 | Ng7 | +23 |
| 25 | Rc1 | +22 | Nf5 | +19 |
| 26 | Qf2 | +19 | Qb7 | +12 |
| 27 | g4 | +14 | Ng7 | +8 |
| 28 | Qg2 | +13 | Nge8 | +19 |
| 29 | Rhe1 | +20 | Qb8 | +19 |
| 30 | Rc6 | +24 | Bg7 | +16 |
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 36.9 moves.
Sample game 1 (1/2-1/2)
1. b3 d5 2. h4 b6 3. e3 c5 4. Bf3 g6 5. Bxh8 Rxh8 6. c4 Bb7 7. Qd3 Nf6 8. cxd5 Nxd5 9. h5 Rg8 10. hxg6 hxg6 11. Nc3 O-O-O 12. Qc4 Nxc3 13. Bxb7+ Qxb7 14. Qxc3 Nc6 15. Rh7 Rgf8 16. d4 cxd4 17. exd4 Kb8 18. Ne2 Qd7 19. Rc1 Kb7 20. b4 Rc8 21. Rd1 Qd5 22. b5 Qxb5 23. d5 Nd8 24. Qf3 Kb8 25. Nd4 Qd7 26. Rh4 e5 27. dxe6 Nxe6 28. Nxe6 Qxe6 29. Qg3+ Ka8 30. Rhd4 Qf5 31. Qa3 Qc5 32. Qf3+ Qc6 33. Qf4 f6 34. Qh6 g5 35. Rd7 Kb8 36. Qg7 Rg8 37. Qh7 Rh8 38. Qg7 Rhg8 39. Qh7 Rh8 40. Qg7
Sample game 2 (1/2-1/2)
1. b4 d5 2. h4 Nd7 3. d4 g6 4. Nd2 Nd6 5. Ncb3 b6 6. e3 Qc6 7. Bf3 e5 8. b5 Qxc2 9. Bxd5 Qxa2 10. h5 exd4 11. hxg6 hxg6 12. e4 Nc5 13. Nxd4 Qxd2 14. Nf3 Qd3 15. Bxh8 Qxf1+ 16. Kxf1 Ke7 17. Ba1 Bd7 18. Ne5 Bxb5+ 19. Kg1 Nd7 20. Ng4 c6 21. Rh7 Rde8 22. Ba2 Bc4 23. Bxc4 Nxc4 24. f4 a5 25. Nh6 Rgf8 26. g4 a4 27. e5 Nc5 28. f5 gxf5 29. e6 Nxe6 30. gxf5 Kd7 31. fxe6+ Rxe6 32. Rd1+ Kc7 33. Bg7 Rg6+ 34. Kh2 Rd8 35. Rxd8 Kxd8 36. Nxf7+ Kc8 37. Bh8 a3 38. Ne5 Nxe5 39. Bxe5 Rg5 40. Bc3 c5 41. Ra7 b5 42. Rxa3 b4 43. Bf6 Rg6 44. Rf3 Kb7 45. Be7 Kb6 46. Rf5 Rc6 47. Kg3 b3 48. Bf6 Rxf6 49. Rxf6+ Ka5 50. Rf8 Kb4 51. Kf4 b2
Play it in the CH960 app
Open this page on a phone with the CH960 app installed, or find pair 49 / 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/BNNBRQKR w EHdg - 0 1
Mirror twin (the same position mirrored): White 907 vs Black 850.
Current place in the live balance rating: 83.