Kakuro Online Free | How to Solve Every Puzzle + Strategy

Kakuro looks like a crossword but plays like a math puzzle. You fill white cells with digits 1 through 9 so that each row or column of cells adds up to the clue in the black cell beside it. No digit can repeat in the same run.

The problem most people hit: they treat it like Sudoku and get stuck. Kakuro has its own logic, and once you learn the key combinations, puzzles that looked impossible become straightforward.

Play Kakuro free online here — multiple difficulties, pencil notes, hints, no sign-up.

What Makes Kakuro Different

In Sudoku, you're placing 1-9 in rows, columns, and boxes with no arithmetic. In Kakuro, every group of cells has a target sum, and the same digit can appear in different groups — just not twice in the same run.

This means your thinking shifts from "where does 5 go in this row?" to "what numbers can add up to this clue without repeating?"

The Forced Combinations (Memorize These First)

Some clues only have one possible digit combination. These are free squares — solve them first.

2-cell runs:

• Sum 3 = 1+2 (only option)
• Sum 4 = 1+3 (only option)
• Sum 16 = 7+9 (only option)
• Sum 17 = 8+9 (only option)

3-cell runs:

• Sum 6 = 1+2+3 (only option)
• Sum 7 = 1+2+4 (only option)
• Sum 23 = 6+8+9 (only option)
• Sum 24 = 7+8+9 (only option)

4-cell runs:

• Sum 10 = 1+2+3+4 (only option)
• Sum 11 = 1+2+3+5 (only option)
• Sum 29 = 5+7+8+9 (only option)
• Sum 30 = 6+7+8+9 (only option)

When you see these clues, fill them in immediately with pencil marks showing all possible digits for that run.

Strategy 1: Start at the Intersections

Every white cell belongs to both a horizontal and a vertical run. The intersection of two forced combinations is often solvable by itself.

Example: A cell that's in a 2-cell run summing to 17 (must be 8 or 9) AND a 3-cell run summing to 6 (must be 1, 2, or 3) — the only digit in both sets is... none. That means you misread something or one of the clues forces a different path. That's Kakuro telling you where to look.

When the sets overlap, you've found your digit.

Strategy 2: Use the Sum Range

For any run of N cells, the minimum possible sum is 1+2+3...+N (sequential from 1) and the maximum is 9+8+7...+(10-N).

• A 5-cell run must sum between 15 (min) and 35 (max)
• If the clue is 16, the digits have very little wiggle room — you're constrained to something like 1+2+3+4+6

This narrows down which digits are even possible in each run before you solve intersections.

Strategy 3: Pencil Marks Are Not Optional

On medium and hard Kakuro, you cannot hold all possibilities in your head. Use pencil marks aggressively:

1. Write all candidate digits for each cell based on the run's clue and length
2. When you determine a digit is impossible (because it would repeat, or the sum wouldn't work), erase that candidate
3. When only one candidate remains, that's your answer

The Kakuro game on PlayBrain has a pencil note mode — tap the pencil icon to switch between placing answers and placing candidates.

Strategy 4: Eliminate by Exclusion

If a digit appears in the forced combination for a run, it cannot appear in the overlapping run at the intersection.

Example: A horizontal run of 2 cells summing to 3 must be {1, 2}. If a vertical run passes through one of those cells, neither 1 nor 2 can appear again in that vertical run (in that cell's position).

Cross out impossible digits from pencil marks as you solve each cell.

Strategy 5: Work the Extremes

Runs with very high or very low sums are the most constrained. A 6-cell run summing to 21 is close to the minimum (1+2+3+4+5+6 = 21), which means almost all the digits must be at the low end. A 6-cell run summing to 44 is near the maximum, so expect digits like 5, 6, 7, 8, 9.

High and low extremes give you the most information with the least work.

Difficulty Progression

Easy Kakuro (smaller grids, more forced combinations): Focus on finding all forced combinations first. Intersections almost always crack the puzzle.

Medium Kakuro (larger grids, fewer forced combinations): Pencil marks become essential. Work the extremes and eliminate systematically.

Hard Kakuro (large grids, ambiguous clues): You'll need to make candidate lists for entire runs and do several rounds of elimination before any cell is certain.

Why Kakuro Is Worth Learning

Kakuro trains a different kind of logic than Sudoku. It builds arithmetic fluency naturally — you stop counting and start recognizing sum patterns instantly. After a week of daily Kakuro, you'll know that 8+9=17 and 6+7=13 without thinking.

The puzzle scales cleanly too. A 5x5 beginner Kakuro takes 3 minutes. A 15x15 expert grid is a genuine brain workout. Both use exactly the same rules.

Play Kakuro free at PlayBrain — beginner to hard difficulty, hint system, pencil notes included. No download, works on any device.

Related puzzles if you like Kakuro: Sudoku, KenKen, Futoshiki.