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Medium Sudoku — Play Free Online

Intermediate Sudoku with 28-34 starting clues. Most solvers finish in 15 to 25 minutes. This is the difficulty where scanning stops being enough and pencil marks start earning their keep.

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Why medium feels different from easy

Drop 7-10 clues from an easy puzzle and something shifts. The long scans that used to reveal a number now leave you staring at four or five candidates per cell. Your eyes can't brute-force the grid anymore — you have to track possibilities. This is where Sudoku stops being a scanning exercise and starts being a real logic puzzle.

Medium is also the difficulty where most casual players camp out. It's tough enough to feel satisfying, soft enough to finish on a coffee break. If you solved easy puzzles under 8 minutes consistently, medium is your next step.

The three new techniques

1. Naked Pairs

When two cells in the same row, column, or box both have the same two candidates — say both only can be {3,7} — those two digits are "locked" into those two cells. You can eliminate 3 and 7 from every other cell in that row/column/box.

2. Hidden Pairs

The reverse. If the digits 4 and 9 can only appear in the same two cells of a unit, then those two cells must contain 4 and 9 (in some order) — even if they superficially allow other candidates. Clear the other candidates.

3. Pointing Pairs (Box/Line Reduction)

When a digit's candidates inside a 3×3 box are all confined to a single row or column, that digit must be placed somewhere in that line segment within the box. You can then eliminate that digit from the rest of the row or column outside the box.

Pencil mark discipline

• Only pencil cells that need it. Don't fill candidates in cells where scanning still works — you'll waste time and clutter the grid.
• Start with cells that have 3 or fewer candidates. These are your highest-leverage cells for finding pairs and singles.
• Update after every placement. When you solve a cell, cross out that digit in all peers (same row, column, box). Skipping this step is the #1 cause of stuck puzzles.
• Use the auto-candidate feature if the UI supports it. It removes the bookkeeping error risk.

Who medium Sudoku is for

Players who've finished easy puzzles consistently and want a real challenge. Commuters and lunch-break solvers — the 15-25 minute window fits a pause in the day. Puzzle enthusiasts who enjoy the feeling of working out a multi-step logical chain. Anyone who wants to practice intermediate techniques before attempting hard or expert.

If you find yourself staring at the grid for 3+ minutes with no progress, try easy for a warm-up. If medium is finished in under 12 minutes regularly, move to hard.

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FAQ

How long does a medium Sudoku take?

15 to 25 minutes for most solvers. Faster if you use pencil marks efficiently; slower if you try to solve by scanning alone.

What techniques do I need for medium Sudoku?

Beyond Naked and Hidden Singles, you'll use Naked Pairs, Hidden Pairs, and Pointing Pairs. These exploit candidate relationships between two or more cells.

Should I use pencil marks on medium?

Yes. Medium is the first difficulty where pencil marks save real time. Start by penciling cells with 3 or fewer candidates.

Is medium harder than the newspaper Sudoku I play?

Newspaper "medium" varies wildly. Our medium sits squarely between easy and hard — roughly equivalent to "3-star" difficulty in most syndicated publications.