DumbLevel

It's just a level.

DumbLevel is a bubble level for hanging shelves and pictures straight, plus a "What are we doing?" screen that does the layout math and hands you the marks. You buy it once. That's the whole deal.

WHAT YOU ARE NOT GETTING
• No subscription. Ever.
• No account. No sign-in.
• No ads.
• No timer. It does not stop working after twenty seconds and ask for money.
• No analytics. Nothing leaves your phone.

THE LEVEL
• Picks the mode by itself. Set the phone on its long edge for a level line, stand it upright for plumb, lay it flat for a two-axis bubble.
• Reads to a tenth of a degree, in numbers big enough to read from a ladder.
• Green, amber, red. Within two tenths of a degree is green.
• Says which end is high, in words: RIGHT END HIGH. TOP LEANS LEFT. LEVEL.
• Hold freezes the reading so you can lift the phone off the shelf and read it.
• Sonar pings that speed up as you get close, and a coin chime when you hit level, so you can watch the shelf instead of the phone. Pings and chime, chime only, or muted.
• Calibration that cancels the phone's own sensor bias. Capture, turn the phone end-for-end on the same spot, capture again. The true tilt cancels out and what is left is the phone's error, which is then subtracted from every reading. It is the same two-capture reversal that precision digital levels use, and it fixes the "my case has a bump on the back" problem.
• The readout turns itself so up on screen is up in the room, whichever way you hold the phone.
• Compared with the level built into the phone: tenths of a degree instead of whole degrees, plus hold, calibration and the hanging planner.

WHAT ARE WE DOING?
Pick the job:
• One picture (or a mirror, a clock, a sign)
• A row of frames
• A grid of frames (a gallery wall)
• Shelves, one or a stack of them
• Hooks
• Curtain rod

Then a few plain questions, with the usual rule already filled in: pictures centered at 57 inches, eye level; 6 to 10 inches above a couch or a dresser; 2 to 3 inches between frames; a curtain rod 4 to 6 inches above the window and 4 to 6 inches past it on each side; coat hooks at 60 inches. Change any number you like.

It does the math and hands you the marks: every one in inches from the end of the wall or the edge of the window, so you can read them straight off a tape. A to-scale drawing shows what you are about to hang. A walkthrough shows one mark at a time in giant numbers so you can make the marks with the phone in one hand and a pencil in the other. Print the sheet or share it as a PDF, tape it to the wall, then tap Level it and the level checks each one.

Every job you measure is filed under Past projects, under the six tiles. Open the hallway you did last spring, see the same numbers, and hang the next frame to match.

FINE PRINT
DumbLevel reads to a tenth of a degree. Like every phone level it is only as good as the sensor inside the phone, so calibrate it before you trust it, and check anything that matters with a real level. It is a phon