Google Bubble Level & Online Spirit Level

Check a surface, align an edge, or measure a slope with your phone.

Sensors not connected

SPIRIT LEVEL / 01

—°

Ready when you are

Lay your phone flat on the surface.

X · LEFT / RIGHT—°

Y · FRONT / BACK—°

Enable your phone’s motion sensors to start measuring.

Say “hold” or “resume”

No phone handy?

Hands-free hold

Adjusting a shelf with both hands? Enable voice control, then say “hold” to freeze the reading or “resume” to continue. Commands are in English.

Optional microphone access · supported browsers only. Say “stop listening” to turn it off. Your browser may process audio through its speech provider.

What can you check?

Hang a picture frame

Choose Horizontal and Wall placement. Rest the phone’s horizontal screen edge on the frame’s top edge. Adjust gently, then listen for the tolerance beep.

Check a desk or small table

Choose Dual Axis and Surface. Rest the phone face up with even contact. Check left-to-right and front-to-back tilt before adjusting the feet.

Align a shelf

Check different points along the shelf using the same phone edge. Enable voice control and say “hold” to freeze a reading while your hands are busy.

Check a doorframe upright

Use for a doorframe or post that must stand upright in both directions. Wall is selected automatically. Align the vertical screen edge with the upright, top of screen up. The line shows sideways lean; the number combines sideways and forward/backward lean. The total is always positive or zero.

Set up a camera platform

Use Dual Axis on a flat tripod platform before attaching the camera. A centred bubble helps you compare both tilt directions; verify the final camera horizon separately.

Compare a slope

Select Inclinometer and align the horizontal screen edge with the slope. Read degrees and percentage grade, then save readings from different positions for comparison.

For everyday checks only. Camera bumps and uneven cases affect contact. Use an appropriately calibrated physical instrument for precision work, structural decisions or compliance checks.

Features

Five measuring modes: Dual Axis, Horizontal, Vertical, Plumb Line and Inclinometer.
Surface and Wall placement: Instructions and readings adapt to a face-up or upright phone. Plumb Line selects Wall automatically.
Clear, large displays: Full-width horizontal vial, enlarged vertical and dual-axis levels, high-contrast bubbles, centre lines and degree markings.
Angles and gradient: Degree readouts with percentage grade in Inclinometer mode; axes follow screen rotation.
Adjustable tolerance: Choose ±0.2°, ±0.5° or ±1°. This is the acceptance threshold, not a claim about sensor accuracy.
Sound feedback: Optional beep after the reading stays inside tolerance for a moment. It stays quiet while the reading remains there. A test button checks your audio.
Hands-free voice control: Say “hold,” “resume” or “stop listening” in supported browsers. Requires microphone permission; browser speech services may process audio online.
Hold and relative zero: Freeze a reading, set the current position as a relative reference, or reset zero. Changes of mode, placement or screen orientation clear the reference.
Local measurement history: Save up to ten readings in this browser, including their mode, placement and time. Demo and relative readings are labelled. Clear them whenever you wish.
Two layouts and themes: Choose Modern or Classic bubble. Dark mode is the default. Full screen expands your chosen level in landscape and requests automatic rotation where supported. Double tap to exit.
Keep the screen awake: Optional screen wake lock where supported, while the page remains visible.
Interactive demo: Explore simulated tilt with sliders when sensors are unavailable. Exit demo returns you to normal measuring controls.
Sensor status and help: Clear permission, missing-data and placement messages. Readings stay blank until sensor data arrives.
No app installation: Use a compatible mobile browser. Sensor calculations run on your device; no advertising or analytics scripts are included in the tool.
Colour and sound feedback: Digits and the tolerance message turn green within your chosen tolerance and deep red outside it. Sound is optional: tap Sound to enable a confirmation chime, then hear a chime when a live reading settles within tolerance. Keep media volume up. Held or missing readings do not trigger chimes.
Remove cover & camera bump calibration: A preparation reminder appears when measuring starts. Optional calibration uses a steady live reading on a known level surface to compensate repeatable camera-bump tilt.

Before you measure

This free spirit level uses your phone’s orientation sensors. Open it directly in a mobile browser and tap Start measuring. Allow motion access if prompted, then wait for a reading. Remove a thick or uneven case and make sure the phone rests on a straight edge rather than its camera bump. The display stays blank when sensor data is unavailable.

When to use each mode

Dual Axis

Use for desks, tables or camera platforms. Choose Surface, lay the phone face up with even contact, and adjust until both axes approach 0°. In Wall mode it shows sideways and forward/backward lean separately.

Horizontal

Use for a shelf or the top of a picture frame. On Surface, lay the phone face up to check left-to-right tilt. On Wall, keep the screen upright and rest its horizontal edge along the line you want level.

Vertical

Use for front-to-back tilt on a tabletop or forward/backward lean of a wall or post. On Surface, lay the phone face up. On Wall, point the screen’s top upward and keep the phone’s back flush against the surface, or align its vertical edge in the direction of lean. The signed reading passes through 0° at upright; leaning toward and away moves the bubble to opposite sides. It does not include sideways lean—check that with Horizontal or Plumb Line.

Plumb Line

Inclinometer

Use to compare a sloping board or shelf. Align the horizontal screen edge with the slope. Select Surface when the phone is face up, or Wall when upright. Read the signed angle and percentage gradient; 45° equals 100% grade.

Taking a reading

Surface: phone face up

Rest the phone flat, screen facing upward, with stable contact. Dual Axis checks both directions, Horizontal checks left/right and Vertical checks front/back. A camera bump or thick case can tilt the phone; avoid uneven contact.

Wall: phone upright

Point the top of the screen upward. Keep the back flush for a wall check, or use a straight screen edge along the object. Horizontal checks sideways tilt, Vertical checks forward/backward lean, and Plumb Line checks total deviation from upright. In landscape, follow the screen’s current edges.

Before reading: tap Start measuring, allow motion access if requested, then wait for the phone to settle. Reset zero if you previously set a relative reference. The bubble reaches the end beyond ±15°; the number continues to show the measured angle.

Accuracy and setting zero

A phone spirit level is useful for quick DIY checks, but accuracy depends on sensors, positioning and contact with the surface. A displayed decimal is not an accuracy guarantee. Set zero creates a relative reference; it does not prove the reference surface is level. Reset clears that offset. A flat surface can still slope, and a short phone cannot reveal every dip along a long shelf. Verify precision work with a calibrated physical level.

Phone or physical level?

Both help you check alignment, but they measure it differently. An online level uses your phone’s orientation sensors. A traditional spirit level uses an air bubble in a liquid-filled vial. A dedicated digital level is a separate electronic instrument with its own specified accuracy; it should not be confused with a phone app.

Feature	Online / phone level	Physical spirit level
Reading	Angle in degrees, virtual bubble and slope percentage.	Bubble position between reference lines; most standard vials do not show numerical angles.
Accuracy	Depends on phone sensors, case, contact points and reference settings.	Depends on the instrument’s specification, condition and correct use.
Contact length	A short phone edge samples a small area.	A longer rigid body spans more of a shelf or frame and provides a straight edge.
Power and access	Needs battery power and browser sensor permission.	A traditional vial needs neither batteries nor internet.
Best use	Convenient everyday checks, angle comparisons and saved readings.	Repeated site work and longer surfaces; use a suitably specified, checked instrument for precision.

For a quick picture-frame check, your phone may be convenient. For precision installation, use a calibrated instrument appropriate to the job. Setting a phone’s zero on an unknown surface makes it a relative reference—it does not establish true level.

Common questions

What is a bubble level used for?

A bubble level checks whether something is horizontal or vertical. Common uses include aligning shelves, frames, furniture and camera supports. Phone versions estimate orientation using device sensors.

Can I use my phone as a spirit level?

Yes, if your phone and browser provide motion sensor access. Open Spirit Level directly, tap Start measuring and allow access. Most desktop computers cannot supply the required readings.

Is it free, and do I need an app?

It is free to use in your browser. No separate app installation is required.

Is this affiliated with Google?

No. Spirit Level is an independent tool. It is not owned, operated or endorsed by Google.

How do I read a bubble level for slope?

Select Inclinometer and align the horizontal screen edge with the slope. Read the angle and percentage gradient. Percentage grade equals 100 multiplied by the tangent of the angle.

Why is my bubble level not moving?

Tap Start measuring and check motion permissions. Open the page directly in a supported phone browser. Embedded browsers may block sensors. Demo mode does not use real sensor data.

Does calibration make any surface level?

No. Set zero only makes the current position your relative reference. Use a known level surface for comparison, and reset the offset when you want the original sensor reference.

Readings and privacy

Sensor data is processed in your browser. Saved readings remain in local browser storage until you clear them. Optional voice control uses the browser’s speech recognition service, which may send audio to its provider. Spirit Level does not store audio or transcripts. This tool includes no advertising or analytics scripts; the hosting provider may process normal access logs.

Read the full Privacy Policy