Game The short answer
Across 400 endgame positions (10 empty squares, 2617 moves solved exactly), taking a corner was the best move 50.8% of the time. In roughly half of the 246 positions where a corner was available, something else was better. That said, grabbing the corner cost only 5.11 discs on average — far safer than any other rule of thumb we measured.
What we counted
Our earlier articles each took a single position and compared the candidate moves. The trouble with that is the obvious objection: maybe that position was just unusual.
So this time we solved positions in bulk. Othello endgames can be read to the very last move, which means we can state how often a piece of common advice was actually right as a measured number rather than an impression.
Method
We played games out with random legal moves and collected positions with 10 empty squares and Black to move. Duplicates were discarded, and we kept only positions with at least three legal moves, since a position with no real choice tells us nothing.
In each position we solved every legal move exactly, to the end of the game, and recorded the final disc margin. A move counts as "best" if it matched the highest final margin in that position (ties included).
Results
"Positions" is how many of the sampled positions offered that kind of move. "Best" is how often it matched the top final margin, and "average cost" is how many discs you gave up by choosing it.
| Rule of thumb | Positions | Was best | Avg cost (discs) |
|---|---|---|---|
| Taking a corner | 246 | 50.8% | 5.11 |
| Flipping the most discs | 400 | 19% | 13.99 |
| Flipping the fewest discs | 400 | 22.5% | 11.13 |
| Playing an X-square | 153 | 9.2% | 16.77 |
A percentage is hard to picture, so here is one position out of the 400 — the one where taking the corner cost the most. Black can play the corner h1, but it finishes −22, a loss. The best move, a2, finishes +16: a difference of 38 discs.
| Move | Flips | Final margin | Note |
|---|---|---|---|
| a2 | 5 | +16 | — |
| h3 | 3 | −12 | — |
| f1 | 1 | −22 | — |
| h1 | 1 | −22 | Corner |
| e7 | 4 | −26 | — |
| h6 | 2 | −32 | — |
| g8 | 6 | −38 | — |
What the numbers say
Corners really are in a class of their own. They were best 50.8% of the time, more than double any other rule, and cost only 5.11 discs on average when they were not best. You will rarely go badly wrong by taking one.
But "always take it" is too strong. In about half of the 246 positions where a corner was on offer, another move did better. As Two corners, two very different values showed, the endgame is decided by reading it out, not by counting corners.
The number of discs flipped tells you almost nothing. The move flipping the most discs was best 19% of the time, costing 13.99 discs on average; the move flipping the fewest was best 22.5% of the time, costing 11.13. Neither "take more" nor "take fewer" works as an endgame guide. The take-fewer instinct that serves you well earlier in the game does not carry over.
X-squares were the worst by every measure. Best only 9.2% of the time, at an average cost of 16.77 discs — the largest of any rule here. The traditional warning holds up.
Limits of these numbers
To be straight about it: these positions come from games played with random moves, so their distribution differs from what strong players reach. In real games, the shapes that force you into an X-square are often avoided long beforehand.
The sample is also specifically the endgame, at 10 empty squares. Nothing here applies to the opening or middlegame. It speaks only to how to choose moves once the endgame has started.
What to remember at the board
- In the endgame, always consider a corner first — it has the best hit rate
- But it is best only about half the time, so read it out before taking it
- How many discs a move flips is not a useful endgame guide
- X-squares are rarely best and cost the most when they are not
Check it in the Othello Dojo
Replay the endgame and pick again, with the evaluation in view. Free, no account.
⚫ Play Othello