4x4 Medium Sudoku Online: Step Up Your Logic Game

4x4 Medium Sudoku is an intermediate number puzzle played on a 4×4 grid with approximately 9–10 starting clues, leaving 6–7 cells blank. Unlike the Easy level — where every blank cell announces itself immediately — Medium puzzles require you to look one step deeper: scanning for cells where a digit can only logically fit in one position within a row, column, or box, even if that cell still has multiple apparent options. This is the difficulty where genuine Sudoku thinking begins. Play free puzzles at any time on SudokuPro.

H2: Characteristics of 4x4 Medium Sudoku

4x4 Medium Sudoku sits at the precise point between mechanical solving and analytical reasoning.

• Grid: 4 rows × 4 columns = 16 cells; four 2×2 sub-grids
• Number pool: Digits 1–4 only
• Starting clues: Approximately 9–10 pre-filled cells (6–7 blank cells)
• Logic required: Naked singles plus hidden singles; pencil marks become useful for the trickier cells
• Typical solve time: 2–5 minutes
• Best for: Solvers who have completed Easy puzzles and want to develop a more systematic approach

The reduction in clue count from Easy means some blank cells will have two valid candidates at first glance. You must examine the broader row-column-box context to narrow each candidate down to one.

Solving Strategies for 4x4 Medium Sudoku

Strategy 1: Naked Singles

As with Easy, begin by scanning every blank cell for ones that already have only one valid candidate after accounting for their row, column, and box constraints. Medium puzzles still contain several naked singles — resolve these first to open up the grid.

Strategy 2: Hidden Singles

A hidden single is a cell that appears to have two or more candidates, but when you examine the entire row, column, or box it belongs to, only one of those candidates can appear in that position — every other valid cell for that digit is already blocked.

How to find them: Pick a digit (say, 3). Find all empty cells in a given row where 3 is still a candidate. If only one such cell exists, that cell must be 3 — regardless of what other candidates it might hold.

Strategy 3: Cross-Hatching by Digit

Take each digit from 1 to 4 in turn. Shade every row and column where that digit already appears. Any empty cell that lies at the intersection of an unshaded row and unshaded column — within an unoccupied box — is a candidate. On Medium difficulty, this technique frequently produces a single candidate per box for at least two or three digits.

Next Steps

Once Medium puzzles feel comfortable, challenge yourself with 4x4 Hard Sudoku, which demands naked pairs and deeper constraint analysis. Looking to revisit fundamentals? Head back to 4x4 Easy Sudoku or browse all difficulty options on the 4x4 Sudoku hub. The SudokuPro How-to-Play guide explains every technique in detail. All puzzles are free on the SudokuPro homepage.