Can two thermometers cross?

No. Thermometers in this game never share a cell.

Do digits have to go up by one?

No. They only have to be strictly larger as you move from the bulb to the tip.

Yes. A solver confirms every puzzle has exactly one solution.

Sudoku with thermometers. Digits along each thermometer rise from the round bulb to the tip, on top of the usual rules.

Thermo Sudoku

0% · Getting ready

A real run of the game, recorded with captions and no sound.

Fill every row, column and 3 by 3 box with 1 to 9, each once.
Each grey thermometer starts at a round bulb. The digits must strictly increase from the bulb to the other end.
A thermometer of length four means its cells hold four different digits in rising order, so the bulb is at most 6.
Tap a cell, then a number. Notes and Erase work as usual. Conflicts, including a broken thermometer, turn red.

Controls: mouse, touch or keyboard. Made by CalcoTools.

Work out the lowest and highest each thermometer cell can be: the bulb is at most 10 minus its length, and the tip at least its length.
Look where thermometers cross a box. A cell that must be high cannot hold a 1, and one that must be low cannot hold a 9.
Digits that are far apart on a thermometer can be placed by logic even when the cells between them are empty.
Pencil the range of each thermometer cell. Narrow ranges meet row and box logic quickly.

Can two thermometers cross?: No. Thermometers in this game never share a cell.
Do digits have to go up by one?: No. They only have to be strictly larger as you move from the bulb to the tip.
Is there a unique answer?: Yes. A solver confirms every puzzle has exactly one solution.