Sudoku Techniques: The Complete List in Learning Order

Every sudoku technique does one of two things: it places a digit, or it removes a candidate so a placement becomes possible. There are dozens of named techniques, but a short list of about a dozen solves nearly every puzzle you will meet in an app or a newspaper. This page lists them in the order you should learn them, from the full house to simple coloring, with a one-line summary of each and a link to a full guide.

The techniques, in learning order

The groups matter more than the exact order inside them. Learn the three singles first, then the two locked-candidate techniques (pointing and claiming), then pairs, then triples, then the advanced patterns. That is also the order a good solver checks the board in: always look for the cheapest move first.

1. Singles: the placements

Singles are where most of the digits in any puzzle come from. You can find all three by eye, without pencil marks.

• Full house: a group with one gap. The missing digit goes there.
• Naked single: look at one cell. If its row, column, and box already use eight digits, the ninth goes in.
• Hidden single: look at one digit in one group. If it has only one legal cell, it goes there. Hidden singles do more work than any other technique on easy and medium puzzles.

An easy puzzle can be solved with singles alone. If you are new to the game, start with how to play sudoku, then come back here.

2. Locked candidates: pointing and claiming

These are the first elimination techniques, and they are the reason medium puzzles feel different from easy ones. Both use the overlap between a box and a line (a row or column).

• Pointing: inside one box, a digit can only go in cells that sit on one row. The digit must be in that row within this box, so it can be removed from that row in the other two boxes.
• Claiming (box-line reduction): inside one row, a digit can only go in cells within one box. It must be in this box on that row, so it can be removed from the other cells of the box.

Both are covered with examples in our pointing pairs and box-line reduction guide.

3. Subsets: pairs and triples

Subsets need pencil marks. They come in two mirror forms. A naked subset is N cells with only N candidates between them. A hidden subset is N digits that only fit in N cells.

• Naked pairs: the most common subset.
• Hidden pairs: harder to see, same logic.
• Naked triples: three cells, three digits. No single cell needs all three.
• Hidden triples: three digits squeezed into three cells.

Quads exist too, but they are rare, and a quad in a group usually leaves an easier pattern among the group's other cells.

4. Advanced patterns

Hard and expert puzzles need logic that spans several groups at once.

• X-Wing: a digit restricted to the same two columns in two rows (or the same two rows in two columns).
• Swordfish: the same idea across three rows and three columns.
• XY-Wing: a pivot cell and two pincers, all with two candidates.
• Simple coloring: two-color chains on one digit.

5. Expert patterns

Most players never need these outside the hardest puzzles. Each guide has a worked example from a real puzzle.

• Skyscraper, 2-String Kite and Empty Rectangle: two strong links on one digit.
• Finned X-Wing and Jellyfish: more of the fish family.
• XYZ-Wing and W-Wing: wings beyond the XY-Wing.
• Unique Rectangles and BUG+1: shortcuts from the one-solution rule.
• X-Chain, XY-Chain and 3D Medusa: chains and colouring.
• Almost Locked Sets: the ALS-XZ rule.

For faster notes on easier puzzles, see Snyder notation. Our advanced strategies guide gives an overview.

How to learn a technique so it sticks

Reading about a technique teaches you the logic. Recognizing it on a live board is a different skill, and it only comes from seeing the pattern many times. A routine that works:

1. Read the rule and walk through one example by hand.
2. Find it in real puzzles at the difficulty where it first appears (see difficulty levels).
3. Do focused reps: many positions in a row where that one technique is the next step, until you see it without searching.

Step 3 is what the Dojo in Sudoku Royale is for. It has a lesson and a timed drill for each of the 13 techniques in the table above, from Full House to Simple Colouring. The advanced drills use positions taken from real graded puzzles, at the exact moment the technique is needed. Read more in our guide to the Dojo technique drills.