How to Use a Level (and Make Every DIY in Your Home Look Totally Pro)

Levels may seem like the domain of pro carpenters and other contractors, but I promise: Whenever you do any sort of interior remodeling, from hanging pictures to installing kitchen shelves, you will find yourself in need of a level. That’s why it’s important to know how to use a level to, uh, make things level — everything from cabinets to curtain rods to appliances and, of course, framed art.

I’ve done my share of remodeling over the past couple decades, and along with a tape measure, drill, hammer, and saw collection, a level is part of my standard tool set. I wouldn’t go to any job without one. 

My levels (I have more than one!) are handheld bubble levels — also known as spirit levels — and they aren’t the only types available. A laser level, for example, can make jobs like setting cabinets easier, but it isn’t an essential tool for most DIYers, as long as you have your trusty handheld level handy.

A spirit or bubble level is also known as a carpenter’s level, and it’s a simple tool. Models differ, though, so you’ll need a sense of what to look for if you need one for your interior remodeling project. Here’s what to know before you buy a level, and how to use a level once you have one.

Spirit levels come in lengths from six inches to eight feet (and longer). The longest ones are used for leveling concrete and are known as screed levels, while the shortest ones (six inches) are called torpedo levels. All are types of box levels. Here are the parts to know.

The box is the narrow, rectangular container for the liquid-filled vials that do the actual measurement.

The box can be made of wood, metal, or plastic, and it sometimes has length graduations that allow you to use the tool as a ruler.

Note: Some levels are shaped like I-beams. They work just as well as box levels but are a bit more fragile. 

The vials contain the measuring fluid, which may be water or a “spirit” such as alcohol.

Each vial is partially filled and then sealed, leaving a visible bubble inside.

Noting the position of the bubble with respect to the center lines marked on the vial is how you determine whether or not the object you’re measuring is level.

All levels have two vials arranged perpendicular to each other so you can make horizontal and vertical measurements, and some have a third vial arranged at a 45-degree angle so you can make diagonal measurements.

The base is a precisely ground flat edge. It’s sometimes magnetized to provide stability for measuring the level of metal objects.

The handle is a finger-size hole in the middle of the box that allows you to grip and hold the tool while you’re taking measurements. 

You can buy a spirit level at any hardware store or home supply outlet, and you’ll find them available in a variety of lengths.

A two-foot level is fine for general-purpose uses, but if you’re doing framing or outdoor building, you’ll get more accuracy using a four-foot level.

When doing interior handiwork, you’ll probably also need a six-inch torpedo level, because it fits in cramped spaces. This is especially true for plumbing (yes, a level is essential for doing drainage work). 

You don’t need to go broke buying a basic bubble level. I bought my plastic two-foot and torpedo levels at the dollar store, and I’ve never needed more expensive ones.

If you make your purchase online or at a hardware store, you shouldn’t have to spend more than $20 for either a two-foot level or a torpedo level.

You’ll find more expensive models, but they are generally intended for pros. For those who prefer top-quality tools, highly durable two-foot levels with adjustable vials are available for just under $100.

When you use a level to measure horizontal level, it’s called leveling, but when you measure vertical level, it’s called plumbing. (Can English be more confusing?) 

Here’s a step-by-step procedure for doing both operations accurately.

A two-foot box level works for most interior purposes, such as cabinets, appliances like refrigerators and air conditioners, or pictures, and it’s fine for plumbing studs, door frames, and window openings.

Choose a six-inch torpedo level whenever there isn’t enough space for a longer one. As long as the surface you’re measuring is flat, the results will be just as accurate. 

Pro tip: If you think you need a longer level, you probably don’t. Here’s a workaround for checking the level on a floor or a long countertop: Find a long, straight 2×4, place it on the surface, and set your two-foot level on that. As long as it’s straight, the 2×4 will extend the base of your level to its length.

Make sure the base is completely in contact with the surface, or you’ll get a false reading. If there are obstructions in the way, such as nails, splinters, blobs of paint, or hardened joint compound, remove them before taking the measurement.

Refer to the vial that’s parallel to the ground. If you’re doing a horizontal measurement, that will be the vial parallel to the base, and if you’re doing a vertical measurement, it will be the one perpendicular to the base. The surface isn’t plumb or level if the bubble stays outside the center line markings. 

Adjust the tilt of the surface you’re measuring to make the bubble fit exactly between the center lines. 

Pro tip: If you can’t move the surface (perhaps it’s a heavy cabinet or a wall stud that has already been fastened), use this method: Tilt the level to center the bubble, then measure the distance from its upper end to the surface, using a ruler or tape measure. This will allow you to calculate (using a little math) how far you need to move the corresponding end of the surface to make it plumb or level. 

Example: Suppose you’re checking the level of an eight-foot countertop, and the distance between the surface and the upper end of your two-foot level when the bubble is centered is 1/4 inch. The countertop is four times as long as the level, so its lower end must be raised 4 X 1/4 = 1 inch to make it level. 

Unlike a spirit level, a laser level isn’t a hand tool. When you use one indoors, you place it in a strategic location in a room and it casts a perfectly level red or green laser line on one wall or, depending on the model, on all four walls.

A laser line provides a reference for aligning cabinets and hanging art, and during construction, it’s useful for framing windows, doors, and other features. Laser levels can also emit perfectly straight vertical lines, which makes them useful for plumbing wall studs as well as doors and windows.

If you do a lot of construction or remodeling, whether indoors or outdoors, a laser level is a useful addition to your tool collection. Everything it does can also be done with less expensive and more portable hand levels, though, so a laser level is a bit of a splurge for casual DIYers.