A Thermometers puzzle with one true answer.
Every row and column has a number. Every thermometer fills from the bulb. Work out where the mercury stops and the grid clicks shut. 660 curated puzzles, a fresh trio every day, no subscription.
Free on iPhone and iPad, with two optional one-time purchasesTouch any cell to take over. This is level 1 of the 6×6 First Heat chapter, exactly as it ships in the app.
Solved.
- Size
- 6×6
- Chapter
- First Heat
Three rules. No guessing.
A grid of glass thermometers, and a number beside every row and column.
- 1The number says how many cells in that row or column hold mercury.
- 2Mercury starts at the bulb and rises without gaps.
- 3A thermometer can be empty, full or filled partway.
Play the counts against the shapes and every cell gives itself up. Mercuro’s solver checks that each board has exactly one answer, so the logic always holds.
Rules, plus a puzzle to tryStart
Tap. Rise. Solved.
Mercury runs up the glass with every tap, with sound and haptics under your thumb. Clues turn teal the moment their line adds up.
Close the last thermometer and the solve card drops in with your time, your chapter and the next level waiting.
A fresh trio every day
A Warm-Up on 6×6 or 7×7. A Daily on 8×8 or 9×9. A Challenge anywhere from 10×10 to 12×12. Everyone gets the same three on the same date, so today’s Challenge is something to argue about.
Missed one? The last two weeks wait in the archive. More on the daily puzzles.
Real boards from one day of Mercuro’s daily calendar, solving in the order the clues allow.
Eight sizes. 660 puzzles. One climb.
Start on 5×5 and work up to 12×12. 330 puzzles are free, with 50 on each of the three smallest sizes, 40 on each of the middle three and 30 on 11×11 and 12×12. Mercuro Pro adds another 330.
Every size runs in chapters of ten with names that heat up, First Heat, Warming Up, Simmer, Rolling Boil, Red Hot. Solve 7 and the next chapter opens.
Hints that show their working
Stuck? Mercuro finds the next move the clues force, lights up the thermometer and the line behind it, and tells you why in a sentence. Row 3 needs 3. Fill this tube to 1.
You see the deduction, make the move, and own it next time.
Nine looks. Two from day one.
Riso paper with hard ink edges, cool glacier blue, deep midnight. Glacier and Slate, one light and one dark, are yours from the first launch. The other seven unlock as you solve, from Coral at 50 to Riso Paper at 330, or all at once with Pro.
From Novice to Virtuoso
Eight ranks, and every step past Novice hands you a new theme. Virtuoso sits at 330 solves, the whole free set, so the summit is open without paying a cent.
Stats keeps your streak and your week of dailies in one glance. Game Center leaderboards rank weekly solves, all-time solves and streaks, for anyone who likes a scoreboard.
- Virtuoso330 solvedUnlocks Riso Paper
- Sage300 solvedUnlocks Forest
- Expert250 solvedUnlocks Porcelain
- Adept200 solvedUnlocks Midnight
- Journeyman150 solvedUnlocks Matcha
- Artisan100 solvedUnlocks Plum
- Apprentice50 solvedUnlocks Coral
- NoviceFree to startGlacier and Slate
A sample climb from 0 to 330 solves. Your own rank moves as you play.
A sample week. Your own grid fills in as you play.
40 achievements. 1,000 points.
First Heat for your first solve. Full Forecast for all three dailies in one day. Year of Heat for a 365-day streak. Tap any badge to see what it takes.
Pay once. Or never.
The dailies and 330 puzzles are free. $2.99 once clears the ads, $4.99 once adds 330 puzzles and every theme. Nothing renews.
- Puzzles330 in chapters
- Daily puzzlesThree a day
- AdsA full-screen ad every third puzzle, at most 12 a day
- HintsTwo a day, then one per short optional ad
- ArchiveEach past day opens after a short optional ad
- ThemesGlacier and Slate, the other seven earned by solving
US App Store prices. Your App Store shows the price in your own currency. Nothing renews.
What the other Thermometers apps charge
| App | One-time purchases | Subscription | Puzzles |
|---|---|---|---|
| Mercuro | $2.99 Remove Ads, $4.99 Pro | None | 660 curated, 5x5 to 12x12 |
| Grids of Thermometers | $0.99 Remove Ads, $0.99 packs, $5.99 all packs | $4.49 Premium Subscription | Thousands of levels |
| Thermometers - Logic Puzzles | $3.99 remove-ads pack | $3.99 a month or $1.99 a week | 9,000+, 4x4 to 17x17 |
| Logic Puzzles - Thermometers | None listed | $0.49 a week, $1.39 a month or $13.90 a year | Thousands |
Go deeper
- How to play Thermometers puzzlesThree rules and a 4x4 solved move by move.
- 6×68×811×11Three new logic puzzles every dayWarm-Up, Daily, Challenge, and a two-week archive.
- $4.99onceA logic puzzle game with no subscription330 puzzles free. $2.99 or $4.99, paid once.
- Like Sudoku or nonograms? Try ThermometersWhat carries over, and the one rule that is new.
- Level packs$4.49 subscriptionPay onceA Grids of Thermometers alternativeNo packs, no subscription, three dailies a day.
- 5×57×79×912×12An alternative to Thermometers - Logic Puzzles660 curated boards against a library of 9,000.
How Mercuro is built, the solver, generator and hint engine behind these puzzles.
Questions
Something else? Ask on the support page.
Is Mercuro free?
Yes. 330 puzzles and the three daily puzzles are free, supported by ads. Two optional one-time purchases remove ads ($2.99) or add 330 more puzzles with no ads ($4.99). There is no subscription.
Where do ads appear?
In the free game a full-screen ad plays every third puzzle you start, at most 12 a day. You get two free hints a day, and after that a hint, or a past day in the archive, costs a short optional ad. Either purchase removes all of them.
How do you play Thermometers?
Fill cells with mercury so each row and column has as many filled cells as its number. Mercury always starts at a thermometer’s bulb and rises without gaps.
Do I ever have to guess?
No. Every board has exactly one solution, and you can reach it by logic alone.
How many puzzles are there?
660 curated puzzles: 330 free and 330 in Mercuro Pro, across eight board sizes from 5x5 to 12x12. Three new daily puzzles arrive every day on top of those.
Does Mercuro work offline?
Yes. The puzzles, including the daily ones, are built into the app.
Which devices does it run on?
iPhone and iPad with iOS 17 or later. The App Store also lists it for Macs with Apple silicon and for Apple Vision Pro.
Is Mercuro on Android?
Not yet. Today it is on iPhone and iPad.
Who makes Mercuro?
Arbaz Siddiqui, an independent developer. How Mercuro is built explains the solver, generator and hint engine.
Today’s trio is on the board
Warm up on the small one. Finish on the Challenge.