Play Thermometers Online — Free
Fill thermometer shapes with mercury from the bulb end upward. Row and column clues tell you how many cells are filled in each line.
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About Thermometers
Thermometers is a logic puzzle where you fill thermometer shapes drawn in the grid. Each thermometer has a bulb end and a tip. Mercury always fills from the bulb upward — you can never skip a cell — so each thermometer is either empty, partially filled from the bulb, or completely full. Row and column clues tell you how many total cells are filled in each line.
The contiguous-fill constraint is what makes Thermometers unique. You’re not choosing individual cells; you’re choosing a fill level for each thermometer. A three-cell thermometer can be: empty, one cell filled (bulb only), two cells filled, or three cells filled (full) — just four possible states regardless of orientation.
Thermometers rewards systematic thinking about which fill levels are consistent with the row and column totals. When a thermometer spans multiple rows, its fill level affects both simultaneously, creating a coupling that powers rapid deduction.
Rows whose clue equals the total cells of all thermometers crossing them are completely full — mark every thermometer cell in that row as filled. Rows with clue 0 are completely empty.
Frequently asked questions
What is the Thermometers puzzle?
The grid contains thermometer shapes. You fill them with mercury starting from the bulb end. Mercury always fills from the bottom/left up without gaps. Numbers on rows and columns tell you how many cells are filled.