All Sudoku Variants
9×9 · Comparison

Greater Than Sudoku

Also known as Comparison Sudoku, Inequality Sudoku

Inequality signs between cells in each box show which digit is larger — often the only clues given.

5 3 8 9 2><

An example Greater Than puzzle: each sign points at the smaller digit — here 5 > 3 < 8.

Greater Than Sudoku replaces most of the given numbers with inequality signs. Between neighbouring cells sits a > or < pointing at the smaller digit, so each sign tells you which of the two cells is larger. Many Greater Than puzzles give no starting digits at all — the arrows of inequality, chained together, are enough to solve the grid on their own.

The rule: follow the signs

An inequality always opens toward the bigger digit and points at the smaller one, exactly as in maths: 7 > 2 reads "seven is greater than two". The signs usually sit between cells inside the same 3×3 box. Everything else is ordinary Sudoku — every row, column and box still needs 1–9 once — so the inequalities are an extra layer on top.

7 2 3 8><

The sign points at the smaller digit: 7 > 2, and 3 < 8.

Reading a chain: order becomes range

A single sign is weak, but a run of them is powerful. When several cells are linked nose to tail — a < b < c < d — the chain behaves just like a thermometer: the values must climb, so each cell gets a window. In a rising chain of four, the first cell needs three larger digits above it (so it is at most 6) and the last needs three smaller below it (so it is at least 4). Work inward and every cell is pinned to a range before you use any other clue.

1–62–73–84–9<<<

A rising chain of four forces a window on every cell — the low end can be at most 6, the high end at least 4.

Extremes and peaks

Look for cells where every neighbouring sign points away — that cell is a local peak and must be large; a cell all of whose signs point in is a valley and must be small. A cell that is greater than three of its box-mates cannot be smaller than 4; one that is greater than all it touches often has to be 8 or 9. These peak-and-valley cells are the fastest way to break into a grid that begins with no digits at all.

Solving strategy

  • Find the longest chains. Like thermometers, the longer the run of inequalities, the tighter the windows at both ends.
  • Pin the peaks and valleys. A cell larger than several neighbours has a high floor; a cell smaller than several has a low ceiling.
  • Combine with the box. Nine cells, nine digits — once a few are ranged, the box's missing digits slot into the only windows that fit.
  • Work both directions. Every > is also a < read the other way; use whichever end is more constrained.

Common mistakes

  • Reading the sign backwards. The wide end faces the larger digit, the point faces the smaller — get it wrong and the whole chain inverts.
  • Treating a chain as fixed values. A < b only means b is bigger, not that they are consecutive — leave room for gaps.
  • Forgetting the box still needs 1–9. The inequalities narrow the order, but the ordinary Sudoku rules place the actual digits.
  • Missing the peaks. A cell greater than all its neighbours is a huge clue — do not overlook it while chasing chains.

Can I play it here?

Not yet — Greater Than Sudoku isn't one of the puzzle types SudokuStreak generates for now. But you can learn its rules above, and there's plenty here to sink your teeth into meanwhile: