Level vs Plumb Quiz: Test Yourself
Five quick questions on level vs plumb. Pick an answer to get instant feedback.
Flip Cards: Quick Review
Hover over a card, or tap it on mobile, to see the meaning.
Perfectly horizontal and flat.
“Make sure the shelf is level.”
Perfectly vertical, straight up and down.
“The fence post must be plumb.”
A weight on a string that hangs straight down.
“He used a plumb bob to mark the ceiling point.”
Leaning, not perfectly vertical.
“The old wall is slightly out of plumb.”
Level vs plumb is a pair that catches many DIYers out, because people often say “level” when they mean any kind of straight. The two words describe different directions: level is horizontal and plumb is vertical. Getting them right matters whenever you hang shelves, set fence posts, frame walls or install doors.
| Term | Meaning | Part of speech / Category | Example sentence |
|---|---|---|---|
| Level | Perfectly horizontal; flat and even | Adjective | The countertop must be level. |
| Level | A tool that shows whether a surface is horizontal or vertical | Noun (tool) | Grab the level and check the shelf. |
| Plumb | Perfectly vertical; straight up and down | Adjective | The door frame needs to be plumb. |
| Plumb | To check that something is vertical, or to measure depth | Verb | He plumbed the wall before nailing the studs. |
| Plumb | Completely or entirely (informal) | Adverb | We were plumb worn out after the move. |
What does level mean?
Level means perfectly horizontal, with no tilt in any direction. A level surface is flat and parallel to the horizon, like the top of still water. In building, you want floors, countertops, shelves and deck boards to be level.
Level is also the name of the tool used to check this. A spirit level has a small vial of liquid with an air bubble, and when the bubble sits between the marks, the surface is level. As a verb, to level means to make something flat or even, as in “level the ground before laying the patio.”
The word traces back through Old French to a Latin word for a balance, which fits the idea of something evenly weighted.
What does plumb mean?
Plumb means perfectly vertical, straight up and down. A plumb wall does not lean forward or backward, and a plumb post stands straight. When a wall leans slightly, builders say it is out of plumb.
The classic plumb tool is a plumb bob, a weight hung from a string. Gravity pulls it straight down, so the string shows true vertical. Modern spirit levels have a separate vial for checking plumb, and laser tools can project a vertical line too.
Plumb also has a few non-building uses. To plumb the depths of something means to explore it deeply, a phrase that began with measuring water depth using a weighted line. In informal speech, plumb can mean “completely,” as in “plumb tuckered out.”
Why is plumb connected to plumbers?
Plumb comes from the Latin word for lead, plumbum, because plumb bobs were traditionally made of lead. The same Latin word explains why lead’s chemical symbol is Pb. Plumber comes from the same root, since early plumbers worked with lead pipes.
Level vs plumb: what is the difference?
The difference between level and plumb is direction. Level is horizontal, and plumb is vertical, and the two are at right angles to each other. Think of a flat floor and a straight wall rising from it.
A quick test helps. If you are checking a surface you could set something on, such as a shelf, a floor or a countertop, you want it level. If you are checking something that stands upright, such as a wall, post or door frame, you want it plumb.
Some tasks need both. When framing a wall, the bottom plate should be level and the studs should be plumb. A third term you will hear is square, which means two edges meet at a true 90-degree corner.
How can you remember which one to use?
Match the word to the direction: level lies flat like the horizon, and plumb hangs straight down like a weight on a string. The memory tricks below give you a few more hooks.
Common mistakes with level and plumb
- ✗ Use a plumb bob to check that the floor is flat.
✓ Use a level to check that the floor is flat. - ✗ The wall leans, so it is out of level.
✓ The wall leans, so it is out of plumb. - ✗ Check that the fence post is level.
✓ Check that the fence post is plumb. - ✗ The countertop is plumb, so a marble stays put.
✓ The countertop is level, so a marble stays put. - ✗ Hang a plumb bob to find a horizontal line.
✓ Hang a plumb bob to find a vertical line.
Memory tricks for level vs plumb
- The falling plum: Plumb sounds like “plum.” A ripe plum drops straight down from the tree, and a plumb line does the same.
- The letters: The letter L has a flat, horizontal base, like level. The letter P has a long, vertical stem, like plumb.
- The bubble vials: On a spirit level, the long vial checks level, and the short vertical vial checks plumb.
Level vs plumb FAQ
Is plumb the same as level?
No. Level means perfectly horizontal, while plumb means perfectly vertical.
What does out of plumb mean?
Out of plumb means leaning or not perfectly vertical, such as a wall or post that tilts to one side.
How do you check if something is plumb?
Hold a spirit level against it and read the vertical vial, or hang a plumb bob next to it and compare. A laser level that projects a vertical line also works.
Why is it called plumb?
Plumb comes from the Latin word for lead, plumbum, because plumb bobs were traditionally made of lead.
What does plumb the depths mean?
To plumb the depths means to explore something deeply. The phrase began with measuring water depth using a weighted line.
Conclusion
The level vs plumb question comes down to direction: level is horizontal, and plumb is vertical. Match the word to what you are checking, and use the right vial or tool to confirm. Share this with someone who mixes these up, and retake the quiz above to lock it in.