Vertical Bubble Level
How to Use the Vertical Level
The vertical level checks whether an upright surface is plumb — whether a wall, post, or door frame leans forward or backward. Hold your phone flat against the surface with the screen facing out, and the bubble in the tall tube tells you how true it is.
When the bubble sits dead-center between the marks, the surface is perfectly plumb. If it drifts up or down, the surface is leaning toward or away from you in that direction, and the degree reading shows by how much.
This is different from the Horizontal Level, which checks flat surfaces like shelves and tabletops. Use this one for anything that should stand upright — fence posts, door frames, shelf uprights, wall-mounted art.
Calibrate sets the current tilt as your new zero point. Useful if you're comparing two surfaces rather than checking absolute plumb.
Frequently Asked Questions
When would I use vertical instead of horizontal?
Use vertical when you're checking things that stand upright — walls, door frames, fence posts, shelving uprights. Horizontal is for flat surfaces like tables and countertops. Think of it this way: if you'd hold a traditional spirit level sideways against it, use vertical here.
Can I check if a wall is plumb with this?
Yes. Hold your phone flat against the wall and tap Check Level. If the bubble sits in the middle, the wall is plumb. If it drifts up or down, the wall leans in that direction. Just keep in mind phone sensors are accurate to about ±0.2°, which is fine for DIY but not survey-grade.
The reading seems off compared to my physical level
Phone sensors have a small manufacturing offset — every phone is slightly different. Tap Calibrate on a surface you trust, and that becomes your new zero. Also make sure your phone case isn't warped, since even a slight bend can throw off readings.
How is this different from the horizontal level?
They measure different axes. The horizontal level uses left-right tilt for flat surfaces like tables and shelves. This page uses front-back tilt — what you want for plumb-checking when the phone is held flat against an upright surface. As a rule of thumb: if you'd lay something flat on it, use horizontal; if it stands up, use this one.
Does it work in landscape mode?
It's designed for portrait mode. If you rotate your phone to landscape, the axes swap and the reading won't be correct. Keep your phone in portrait orientation for accurate results. For landscape tilt, the Horizontal Level is more appropriate.