Thermometers Solver

Thermometers Solver — Step by Step

Drag from each bulb to its tip to draw the thermometers, click a count outside the grid and type it, then press Solve. Or play a generated puzzle and send it here with one click.

Thermometers Solver: rules, how to use it, tips

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.

Using the solver

Choose the size, draw each thermometer from bulb to tip and type the counts (or press Sample).
Press Solve and step through: empty lines, full lines and how each thermometer fills from its bulb.

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.