Easy Between Lines Sudoku

Digits on each line must fall between the values at its endpoints. Every line adds a range constraint to the standard rules.

Easy Medium Hard Expert

New to Between Lines Sudoku? Start with lines whose endpoints are close in value — narrow ranges leave very few options for the middle cells.

8
2
3
4
3
6
8
1
7
9
4
5
1
8
8
3
9
1
7
6
9
8
6
3
2
1
8
8
4
5
9
6
7
3
1
3
8
9
Mistakes
0/3
Score
-
Time
00:00
Try Medium Between Lines Sudoku →
Progress0%

What is Between Lines Sudoku?

Difficulty
★★★☆☆
3/5
Constraint Type
Line Constraints
Typical Givens
20–28
Avg. Solve (Easy)
8 min

Solving Techniques for Easy Level

Technique Description Level
Endpoint Gap Analysis The gap between endpoint values must be large enough to accommodate all middle cells. If endpoints are 2 and 8, middle cells must come from {3,4,5,6,7}. Beginner
Endpoint Ordering The endpoint values have no fixed order — the constraint is that all middle cells are strictly between the minimum and maximum endpoint. Beginner

Ready to go deeper? Try Medium Between Lines Sudoku to unlock Intermediate techniques.

Techniques to Master at Easy

  • Last Possible Number technique — Cells along a between line can never hold 1 or 9 — they must sit strictly inside the endpoint range — so every line cell starts with at most seven candidates.
  • Notes in Sudoku — Track each line as an endpoint range, not per-cell lists: tightening either circled endpoint instantly re-prunes every cell strung between them.

Average Solve Time by Difficulty

Easy
8 min
Medium
18 min
Hard
36 min
Expert
64 min
Want a full walkthrough of rules, strategies, and solving steps? How to Play Between Lines Sudoku →

Related Variants

Palindrome Sudoku

Another variant where a line links far-apart cells — mirrored digits there, a shared value range here.

German Whispers

Inverts the comfort zone: between lines squeeze digits into a narrow range while whispers force them far apart.

Thermo Sudoku

Adds full ordering to the range logic you use on between lines — every step along a thermometer must increase.

Frequently Asked Questions — Easy Between Lines Sudoku

What is Between Lines Sudoku?
Between Lines Sudoku adds lines with circular endpoints to a standard Sudoku grid. Every digit along the line (excluding the circles) must be strictly between the two endpoint values in numerical terms. If the circles hold 2 and 8, all middle cells must contain 3, 4, 5, 6, or 7. Standard Sudoku rules still apply.
How do I use between-line clues to solve the puzzle?
Start with lines that have endpoints close together in value — they restrict the middle cells to a very narrow range. A line where the endpoints differ by only 2 (for example, 3 and 5) has only one possible middle value (4). Lines with large endpoint gaps are less constraining, so tackle small-gap lines first.
Can the circles at the ends of a between line repeat within the line?
No — standard Sudoku uniqueness rules apply. Within the same row, column, or box, each digit appears exactly once. The circle cells are normal Sudoku cells subject to those constraints. The between rule applies to the middle cells of the line, not the circles themselves.
Do I know which endpoint is the larger value in Between Lines Sudoku?
No — the two endpoint circles are visually identical. You don't know in advance which is the smaller and which is the larger. The rule only states that all middle-cell values must be strictly between the two endpoints. You discover the endpoints' actual values as you solve the puzzle.
How is Between Lines Sudoku different from Thermometer Sudoku?
Thermometer Sudoku requires cells to increase strictly from the bulb end to the tip. Between Lines Sudoku has two endpoints and only requires that middle cells fall strictly between them — there is no directional ordering for the middle cells, and they don't need to be monotonically increasing.

More questions? See the full Between Lines Sudoku guide.