SPIRIT LEVELSpirit Level – a digital level and inclinometer on your phone
Put your phone on a shelf, ramp or edge and instantly see whether it is level and how many degrees it tilts. Plus an on-screen ruler, flashlight, unit converter and calculator – all in one app, no install.
- Free, no sign-up
- Two-axis leveling and precise angles
- Slope in degrees, percent and ratio
- Zero calibration, sound and vibration when level
- Ruler, flashlight, converter and calculator included
Surface mode
Illustrative example of Surface mode.
Who it's for
For anyone who needs to level or measure something
A real spirit level isn't always at hand – your phone is.
DIY
Shelves, pictures, furniture or a washing machine – see right away whether they are level.
Renovation
A quick check of a floor, sill or step before you reach for the tools.
Campervans and caravans
Level your vehicle at the campsite on both axes at once.
Photo and tripod
A straight horizon and a level tripod without hunting for the bubble.
Tradespeople on the go
Level, ruler, flashlight and calculator in one phone.
Ramps and slopes
Slope of a driveway, roof or ramp in degrees, percent and 1 : n ratio.
How it works
Four steps to an accurate reading
Open the app
All you need is a browser. On iPhone you just allow access to the motion sensors.
Pick a mode
Surface – lay the phone down. Angle – lay it down or stand it on its edge like a classic level.
Calibrate zero
Once, on a surface you know is level. The app remembers the calibration.
Read and save
When level, the bubble turns green and the app beeps. Save a reading with a label and export it to CSV.
Worked example
How the app converts a slope – with real numbers
A driveway or ramp that the app measures at 5°. What does that look like in other units?
- Slope in percent:
tan(5°) × 100 = 8.7 % - Ratio:
1 : (1 ÷ tan 5°) = 1 : 11.4 - Rise over 2 m:
2,000 mm × 0.0875 = 175 mm - In gradians:
5 × 400 ÷ 360 = 5.56 gon - You'll find the same conversions in the app's Convert tab – “Use live angle” inserts the current reading.
Result
- Angle5.0°
- Slope8.7 %
- Ratio1 : 11.4
- Rise over 2 m175 mm
The app also shows the slope in percent right under the reading in Angle mode.
Features
What the app does
Surface
Two-axis bubble – ideal for shelves, tables and appliances.
Angle
Phone lying flat or standing on its edge, targets 0°, 45° and 90°.
Slope in % and ratio
Every angle comes with its slope in percent.
Zero calibration
Evens out your phone or case and stays saved.
Sound and vibration
A beep and a buzz the moment everything is level.
Saved readings
Readings with a label and date, CSV export.
Ruler
Centimeters and inches, calibrated with a bank card.
Full-screen ruler
For longer objects – zero at the top edge, no scrolling.
Flashlight
Camera flash, or a lit screen in several colors.
SOS blinking
The international · · · — — — · · · signal in an endless loop.
Converter
Length (mm to yards) and angle (degrees, radians, gon, %, 1 : n).
Calculator
Quick calculations while you measure, keyboard included.
Tips
How to measure as accurately as possible
A few habits that get the most out of your phone:
Calibrate on a true level
Set zero on a surface you know is level – for example checked with a classic spirit level.
Mind the case and camera bump
A camera bump or case tilts the phone. Always measure the same way and calibrate in the same case.
Turn it 180°
Measure, turn the phone 180° on the same spot and measure again. The average cancels out the phone's own error.
Let the phone settle
The value settles within a fraction of a second – don't read it while the phone is moving.
Calibrate the ruler too
Without calibration it's approximate. With a bank card you set it to the millimeter.
Double-check on site
For construction and professional work, always verify with a classic spirit level.
Data & privacy
What the app does and doesn't do
Where your data lives
- Sensor data is processed only in your browser and never sent anywhere.
- The camera is used only to turn on the flash; no image is stored.
- No account, sign-up or login.
- Saved readings and calibration stay on your device only (localStorage).
- We count visits with GoatCounter – no cookies, no stored IP addresses.
- Download your saved readings as CSV.
Good to know
- Accuracy depends on your phone's sensors – usually tenths of a degree to one degree.
- The ruler only measures objects that fit on the screen.
- On iPhone the screen lights up instead of the flash – the web can't control it.
- Computers usually have no motion sensors – only demo mode works there.
- The app is not a certified measuring instrument.
- For construction, double-check with a classic spirit level.
FAQ
Frequently asked questions
How much does Spirit Level cost?
Nothing. It's free, with no paid features and no sign-up.
How does a digital level in the browser work?
It reads your phone's gyroscope and accelerometer and converts the data to a tilt angle in real time. It runs right in your browser, no app install needed.
Why do I have to allow sensors on iPhone?
Safari requires it for security reasons. Just tap “Enable sensors” and confirm the system prompt.
Does it work on a computer?
Computers usually don't have motion sensors. You can try the interface in demo mode with a slider; for measuring, use your phone.
How accurate is a web-based level?
Usually within tenths of a degree to one degree, depending on the sensors. It's most accurate after calibrating zero on a surface you know is level.
Can I measure the slope of a ramp or roof?
Yes. Angle mode shows the angle in degrees and the slope in percent below it. The 1 : n ratio is in the Convert tab.
How accurate is the on-screen ruler?
Only approximate until you calibrate it. Tap Calibrate, hold a bank card upright against the screen and match the frame to its 85.6 mm length – the app remembers it.
Can I add it to my home screen?
Yes. On Android in Chrome the app offers to install itself; on iPhone, tap Share and then Add to Home Screen.
Want to give it a try?
Open Spirit Level and measure your first surface. Nothing to install, nothing sent anywhere.
Open Spirit Level →