Thermometers
Fill thermometers with mercury using row and column clues.
The rules
How to play
- 01
Bulbs and tips
Every thermometer has a bulb (the rounded end) and a tip (the other end). Mercury always starts at the bulb.
- 02
Fill from the bulb
Mercury fills from the bulb toward the tip and must be continuous — no gaps allowed anywhere along the tube.
- 03
The continuity rule
If a cell is filled, every cell between it and its bulb must be filled too. You can never strand a drop of mercury.
- 04
Read the clues
The numbers beside each row and above each column tell you exactly how many cells are filled in that line.
- 05
Any level is fair
A thermometer may end up empty, partly filled, or completely full — whatever the row and column counts demand.
Play smarter
Ways to read the tubes
Start with 0 clues
If a row or column shows 0, mark every cell in that line as empty (×). Those blanks anchor the crossings.
Maximum fills
When a clue equals the number of cells in its line, fill them all — there is no other arrangement.
Follow continuity
Fill one cell and every cell between it and the bulb must follow. Chase those forced fills down each tube.
Mark empty cells
If filling a cell would exceed a clue, mark it empty. Ruled-out cells quietly constrain the lines they cross.
Watch & learn
Two minutes to mastery
From the Intel desk
Reading for the curious
Thermometers Puzzle: A Complete Beginner's Guide to Temperature Logic
Learn how to solve Thermometers puzzles from scratch. Master the rules of mercury-filling logic, follow our visual step-by-step tutorial, and discover essential strategies for beginners.
Thermometers Strategies: Temperature Logic for Flawless Fills
Master Thermometers with base-first logic, row counting, and mercury flow techniques. Fill every bulb to tip with pure deduction—no guessing.
Keep going
Where to next
Fresh every day
The Daily Thermometers
One shared grid for everyone, every day. Build a streak and compare your solving time.
Go deeper
Rules & strategy guide
From continuity logic to clue counting — the complete written guide with worked examples.
Beyond the grid
Explore all puzzles
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