The sudoku2pdf rating of sudoku puzzles is a single integer that expresses puzzle difficulty on a 1000–2800 scale, analogous to Elo ratings in chess.
The rating of a puzzle is equal to the highest rating of the techniques used to solve the puzzle according to the following table:
| Solving method | Rating |
| Full House, Hidden Single (box) | 1000 |
| Hidden Single (row/column), Naked Single | 1040 - 1100 |
| Pointing Pairs/Triples, Claiming | 1200 - 1320 |
| Naked/Hidden Pairs | 1360 - 1480 |
| Naked/Hidden Triples, X-Wing | 1520 - 1640 |
| W-Wing, XYZ-Wing, Swordfish, Naked/Hidden Quads | 1680 - 1800 |
| Finned X-Wing, Sashimi, Franken Fish | 1800 - 2120 |
| Alternating Inference Chains (AIC), Forcing Chains | 2120 - 2580 |
| Nested Forcing Chains | >= 2600 |
| Backtracking (no human-logic solution found) | 2800 |
We believe that this rating is easier to read than the original Sudoku Explainer decimal values, and leaves room for later refinements if needed.
The difficulty level of a puzzle is related to its rating according to the following table:
| Difficulty | Rating |
| Easy | <= 1100 |
| Medium | 1120 – 1380 |
| Hard | 1400 – 1660 |
| Fiendish | 1680 – 1980 |
| Diabolical | >= 2000 |