about us
A leveler worth trusting.
Who builds LevelerPro, why it works the way it does, and an honest account of what a phone accelerometer can actually tell you.
Works on any phone with a tilt sensor · Runs entirely on your device
Who we are
LevelerPro is a small independent project, not a software company. It exists because a spirit level is one of the few tools everyone needs occasionally and nobody can ever find, while the sensor that can replace it is already sitting in your pocket. The gap was never the hardware. It was that most phone levels are wrapped in adverts, permissions, and sign-up screens.
So this one is a web page. There is nothing to install, nothing to register for, and no adverts. A visit counter tells us how many people use it, and that is the extent of the tracking. It loads in a second, works offline once cached, and reads the same on a building site as it does on a kitchen counter.
What we will not do
Two commitments shape every decision here. The first is that your measurements stay yours: readings are calculated in the browser and never transmitted, and the only stored values are your own preferences. The second is that we will not overstate what the tool can do. A phone is a genuinely useful 0.2 degree instrument and a poor 0.02 degree one, and theaccuracy section below says so plainly rather than claiming a precision the hardware cannot deliver.
the operator
LevelerPro is run by [your name or company here], based in [location]. Written questions are welcome atour contact page.
The level itself is the front page: five vials, full screen, nothing else on it.
Open the Levelwhat it does
Built like an instrument, not a novelty.
edge vials
A vial on every edge.
Four independent green spirit vials ride the top, right, bottom, and left edges of the screen, all live at once. Switch off any you do not need from the settings panel.
bullseye
One vial for both axes.
The centre bullseye tracks pitch and roll at once, the fastest way to level a tripod head, a washing machine, or a table.
calibration
Zero out your device bias.
Every accelerometer sits a fraction of a degree off true. Rest the device on a surface you trust, tap Set Zero, and the offset is stored on your device.
units
Degrees, percent, or per-metre.
Switch between degrees, percent slope, millimetres per metre, and inches per foot. Drainage falls and ramp gradients read directly, with no conversion in your head.
range
Pick your sensitivity.
A ±2° vial resolves a hair of tilt for cabinetry. Open it to ±15° when you are roughing in a slope. The graduations rescale with the range.
privacy
Nothing leaves the device.
The math runs entirely in your browser. There is no account, no upload, and no reading of yours ever leaves the device. Settings stay in local storage.
method
Three steps to a trustworthy reading.
01
Rest the device on the surface.
Lay the phone flat, screen up, with the long edge along the run you care about. Let it settle for a second, because the reading filters sensor noise as it lands.
02
Set zero on a known reference.
Place the device on a surface you trust, such as a machinist’s plate or a countertop you have already checked, then tap Set Zero. That removes your hardware’s built-in bias.
03
Read the raised edge.
The bubble drifts toward the high side, exactly like a spirit vial. Centre it between the two gate lines and the vial turns green at ±0.2°.
accuracy
What a phone can and cannot tell you.
Your device measures gravity, not level. It resolves about 0.1° of change, carries a manufacturing bias of up to a degree, and drifts with temperature. Calibration removes the bias; nothing removes the noise.
So treat a reading inside ±0.2° as level, use the ±2° range for fine work, and reach for a machinist’s level when a tenth of a degree changes the outcome.
the same tilt, four ways
| angle | slope | mm/m | in/ft |
|---|---|---|---|
| 0.1° | 0.17% | 1.75 | 0.021 |
| 0.2° | 0.35% | 3.49 | 0.042 |
| 0.5° | 0.87% | 8.73 | 0.105 |
| 1.0° | 1.75% | 17.46 | 0.209 |
| 2.0° | 3.49% | 34.92 | 0.419 |
Slope units are the tangent of the angle, not a linear scale.
questions
Frequently asked.
How accurate is a phone bubble level?
The MEMS accelerometer in a modern phone resolves tilt to roughly a tenth of a degree, but it ships with a fixed bias that is often several times larger than that. After you tap Set Zero on a reference surface, expect ±0.2° to ±0.5° in practice. That is close enough to hang a shelf and not close enough to set a machine bed.
Why does the bubble drift while the device sits still?
Accelerometer output moves with temperature and picks up vibration from the room. The reading is filtered to hide most of it. If the resting position has wandered since you calibrated, tap Set Zero again.
Nothing moves on my laptop. Is it broken?
Desktops and most laptops have no tilt sensor, so the tool switches to a drag preview: pull the plate with the mouse, or use the arrow keys, to see how the vials respond. Open the page on a phone or tablet for a real reading.
The bubble moves the wrong way. How do I fix it?
Axis polarity differs between vendors and operating systems. Turn on Invert Axes in the controls and the reading flips to match your hardware. The setting is remembered.
Which edges should carry a vial?
Put a vial on the edge that runs along what you are levelling. Checking a shelf left to right? Use the top or bottom vial. Checking a door jamb for plumb? Use the left or right vial. For a surface that has to be flat in both directions, turn on the centre bullseye.
Do I need to install an app or create an account?
No. LevelerPro is a web page. Add it to your home screen if you want a launcher icon, but there is nothing to install, nothing to sign up for, and no readings stored anywhere but your own device.
Privacy, in one paragraph.
The level runs as a static page. Tilt data is read by your browser, used to move a bubble, then discarded. Your unit choice, vial placement, and calibration offset are written to local storage on your own device so the tool opens the way you left it. Nothing is sent anywhere, and the full privacy policy spells out exactly which two values are stored.