Thermometers

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Tap a square to fill up to itTap the top to lowerRight-click marks empty

How to play Thermometers

Every square of the grid belongs to a thermometer — a straight tube with a round bulb at one end. Your job is to fill some of them with mercury.

Mercury always starts in the bulb and rises towards the tip with no gaps: a thermometer can be empty, partly filled or full, but never filled at the top and empty below.

The numbers outside the grid say how many squares are filled in each row and column. Rows of 0 and rows that must be completely full are the best places to start.

How to play Thermometers

Fill thermometers with mercury from the bulb up, with no gaps, so every row and column has the right number of filled squares.

The rules

The grid is divided into straight thermometers, each with a round bulb at one end.
Mercury fills a thermometer from its bulb towards its tip with no gaps. A thermometer may be empty, partly filled or completely full.
The number beside each row and below each column is how many of its squares are filled.

Playing here

Choose a size and a difficulty, then press New Puzzle.
With Fill to here, tap a square on a thermometer to fill it from the bulb up to that square. Tap the top of the mercury to lower it by one.
Mark empty puts a dot in squares you know stay empty; drag to dot several. Right-click also dots.
Counts turn green when a row or column is right; Hint explains the next deduction.

Tips

Zeros first. A row or column with 0 is completely empty — and so is every square further from the bulb on any thermometer passing through it.
Full lines. When a count equals the length of the line, every square is filled — and so is everything between those squares and their bulbs.
Bulb logic. If any square of a thermometer is filled, every square between it and the bulb is filled too. If a square is empty, every square beyond it is empty.
Lying along a line. A thermometer lying along a row with a small count can fill only a few squares; one crossing it can fill at most one.

The full guide, with a worked example and common mistakes: How to play Thermometers.

Questions

Can a thermometer be empty?

Yes — empty, partly filled or full are all allowed.

Are thermometers always straight?

Here they are: each one runs straight across or down.

Is there always one answer?

Yes — every puzzle here is checked to have exactly one solution.

How do I solve one from a book?

Open the Thermometers Solver, draw the thermometers, type the counts and press Solve.

Play Thermometers — Logic Puzzle

How to play Thermometers

How to play Thermometers

The rules

Playing here

Tips

Questions

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