How to Use a Spirit Level: Complete Beginner's Guide

What Is a Spirit Level?

A spirit level (also called a bubble level) is one of the most essential tools in any toolbox. It uses a liquid-filled vial with an air bubble to indicate whether a surface is perfectly horizontal (level) or vertical (plumb). The bubble naturally floats to the highest point, and when it sits exactly between two marked lines, your surface is perfectly aligned.

Getting Started with BubbleLevel

Our free online bubble level tool works right in your browser — no app download needed. Here is how to use it:

1. Open BubbleLevel on your phone or desktop browser.
2. On mobile, tap Enable Device Sensor to activate your phone's gyroscope.
3. On desktop, switch to Simulate mode and drag the bubble to test different angles.
4. Place your device on the surface you want to check — the bubble will show you if it is level.
5. When the outer ring turns green and displays "Level", your surface is perfectly horizontal.

Step-by-Step: Hanging a Picture Frame

1. Mark Your Wall Position

Hold the picture against the wall where you want it. Use a pencil to lightly mark the top corners. This gives you a reference point.

2. Find the Hanging Point

Measure the distance from the top of the frame to the hanging wire when pulled taut. Transfer this measurement down from your top marks to find where the hook should go.

3. Check for Level

Place your phone with BubbleLevel open against the wall at the marked position. If you are hanging two hooks, place the phone across both marks to ensure they are perfectly level with each other.

4. Install and Verify

Install your wall hooks or nails, hang the picture, then place your phone on top of the frame to do a final level check. Adjust as needed.

Installing Shelves

Shelves that are not level look unprofessional and can cause items to roll off. Here is the proper procedure:

1. Mark your desired shelf height on both ends of the wall.
2. Use BubbleLevel in horizontal bar mode — it gives a clearer reading for longer spans.
3. Place your phone along the line connecting your two marks. Adjust until level.
4. Draw a level line between the marks. Install your brackets along this line.
5. After mounting the shelf, place BubbleLevel on top to confirm everything is still level.

Using the Vertical Mode

Switch to vertical bar mode when you need to check if something is perfectly vertical (plumb) — like installing a door frame, aligning a mirror, or setting up a bookshelf against the wall.

Pro Tips for Accuracy

• Calibrate first. Place your phone on a surface you know is level, tap "Calibrate", and the tool will zero-out any device bias.
• Use a flat phone case. A curved or uneven case can tilt your phone slightly. Remove it for best results.
• Check from multiple angles. Rotate your phone 180° and check again — if the reading is the same, your device is accurate.
• Adjust sensitivity. Use the ±15° mode for fine adjustments and ±45° for rough positioning.
• Save measurements. Tap the Save button to record your level readings for future reference or to share with a client.