The most secure way to wall-mount a television, mirror or heavy artwork is to anchor it to a stud.

Wall studs are pieces of wood or metal framing, spaced 16 or 24 inches apart on center, that run vertically inside a wall. Because studs are behind the drywall or plaster, they can't be seen with the naked eye. Nevertheless, there are ways to find wall studs without using a stud finder:

Finding nails - Molding and baseboards are often nailed to studs. An evenly-spread pattern of nails indicates where the studs are and how far apart they are spaced.
Measuring from a window - There are studs on both sides of a window. Knock on the area that is either 16-or 24-inches from the edge. A solid "thud" indicates a stud; a hollow sound means empty wall.
Shining a light - "Look for the silhouettes of nailheads or drywall tape as the side light skims the surface of the wall; you should find a stud directly behind," suggests This Old House.
Knocking on either side of an outlet - Electrical outlets are usually mounted to one side of a stud. Knock on either side of the outlet; the stud is located on the side that sounds more solid.

If these methods don't work, a stud finder might do the trick. There are two basic types:

Magnetic stud detector - A magnet will stick to a wall when a metal stud (or wooden stud with nails driven into it) is behind it. However, magnets don't work well on plaster walls with metal lath.
Electronic stud finder - Handheld, battery-operated stud finders beep or flash when they find a dense part of the wall. Some wall scanners can detect false positives (like water pipes) or live wires.

The best electronic stud finders "use a center-finding density-reading...that will show the edges of your studs," according to BobVila.com. This is useful when hanging particularly heavy or expensive items.

How Much Does a Good Stud Finder Cost?

A good stud finder (with verified, above-average reviews) costs approximately $21, according to a 12-month analysis of price trends. Those same stud finders cost around $15 while on sale: an average discount of 29%. Alternatively, neodymium magnets (available in hardware stores) are an inexpensive alternative. Here are the best budget stud finders for the money:

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1. Johnson Level & Tool 160 Project Studfinder Plus

Good Value: $5 | Great Deal: $2

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Johnson's mechanical stud finder is compact, effective and it has a clever design, according to several online customers. Some reviewers wish this unit had a stronger magnet; others warn that it isn't drop-proof.

2. Zircon Pro StudSensor A100 Wall Scanner

Good Value: $23 | Great Deal: $20

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Zircon's budget wall scanner is effective at locating studs, pipes and wires, according to several customers. Some reviewers warn that this unit requires a new name-brand 9V alkaline battery to function.

3. Franklin Sensors ProSensor M90 Stud Finder

Good Value: $30 | Great Deal: $20

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The Franklin M90 is quick, easy and precise, according to several online customers who say that it's the best electronic stud finder that they've ever used. Some reviewers caution that the M90 doesn't work well on textured walls; others say that the battery door cover comes off easily (especially in a tool bag).

4. CH Hanson Magnetic Stud Finder

Good Value: $7 | Great Deal: $2

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This battery-free stud finder sticks to the wall when it finds a nail, according to several online customers. Many reviewers were amazed by the strength of the device's rare-earth magnets. The manufacturer admits that this tool works better on drywall than it does on plaster.

5. The StudBuddy Plus Magnetic Stud Finder and Level

Good Value: $15 | Great Deal: $12

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This StudBuddy stud finder is accurate, easy to use and particularly convenient because of its integrated level, according to several online customers. One reviewers cautions that StudBuddy isn't effective on acrylic.

6. Zircon MetalliScanner m40: Handheld Metal Detector

Good Value: $40 | Great Deal: $30

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Zircon's handheld metal detector is an effective stud finder for lath and plaster walls, according to several online customers. Some reviewers wish this unit was more durable and ergonomic.

7. MagnetPal - Strongest Magnetic Wall Stud Finder

Good Value: $13 | Great Deal: $11

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This key-chain-sized rare earth magnet is effective at locating nails and screws within various types of drywall and plaster, according to several online customers. Many reviewers warn that MagnetPal is easy to lose.

8. The StudBuddy Magnetic Stud Finder

Good Value: $15 | Great Deal: $9

Made in the U.S.A

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This magnetic stud finder is effective at finding wooden and metal studs that are behind drywall, according to several online customers. Some reviewers say that the StudBuddy is no better than a plain magnet because it doesn't include a built-in level; others say it struggles on lath and plaster walls.

9. Vivreal Stud Finder and 3-in-1 Wall Scanner

Good Value: $27 | Great Deal: $17

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This stud finder effectively finds wall studs behind drywall and plaster, according to several online customers. Some reviewers wish that the unit included a 9V battery and calibrated more quickly.

10. Studpop Magnetic Stud Finder

Good Value: $11 | Great Deal: $9