What It Is
A stud finder is a small hand tool that locates the hidden wooden framing boards behind your finished walls. Robert Franklin invented the first modern electronic version in 1977. The name simply describes exactly what the tool does, which is finding the hidden wooden studs in a wall.
When you look at an interior wall, you just see a flat painted surface. But underneath that surface, vertical wood boards hold your house up. These boards usually sit 16 or 24 inches apart. Your wall material attaches directly to these boards. A stud finder senses changes in the wall density to tell you exactly where those hidden boards live. It beeps or lights up when you slide it slowly over a solid board.
Why You Need One
You use this tool to safely hang heavy items like televisions, large mirrors, or heavy floating shelves. Drywall is mostly made of chalky gypsum dust wrapped in thick paper. It's very weak on its own. If you try to hang a heavy flat screen television using only the drywall, the screws will rip right out over time. Your expensive television will crash to the floor and leave a giant hole in your wall.
To hang heavy things safely, your mounting screws must go deep into the solid wood framing. A stud finder takes the frustrating guesswork out of finding that wood. You don't have to knock on the wall and guess where the hollow sound stops. This makes it a required tool when you tackle weekend projects from our DIY vs. Hiring a Pro guide.
How to Use the Tool
Using an electronic stud finder takes a little bit of practice. First, place the tool completely flat against the wall. Press and hold the power button on the side. Don't move the tool until it finishes calibrating. This usually takes a second or two. If you start moving it too soon, it won't read the wall correctly.
Next, slide the tool very slowly across the wall in a straight horizontal line. When the tool detects the edge of a wood board, it will beep or flash a red light. Use a pencil to mark that exact spot. Keep sliding the tool until the beep stops. Mark that second spot. The space between your two pencil marks is the width of the board. You want to drill your screw right in the middle of those two marks for the absolute strongest hold.
What to Watch Out For
Your walls hide much more than just wood. They also hold water pipes, air ducts, and electrical wires. Sometimes a stud finder will sense a thick plastic pipe or a cluster of wires and beep. This is called a false positive. If you drill into a false positive, you might cause a massive water leak or a dangerous electrical spark.
You can avoid costly mistakes by mapping out the wall. Find a stud, then measure 16 inches to the left or right. You should find another stud right there. If your tool beeps in a random spot that doesn't line up with a standard framing pattern, it might be a pipe. You can learn more about what hides behind your walls in our Interior: Paint, Drywall & Trim guide.
How Much They Cost
You can find these tools at any local hardware store. Prices depend heavily on the technology inside the tool. Keep in mind that exact costs vary based on where you shop and what brand you buy.
- Magnetic finders: These cost 5 to 15 dollars. They don't need batteries. They use strong magnets to find the metal screws holding your drywall to the wood.
- Standard electronic finders: These cost 20 to 50 dollars. They are the most common choice for homeowners. They run on a standard battery and use sensors to measure wall density.
- Advanced digital finders: These cost 60 to 150 dollars. They feature digital screens that show the exact center of the stud. Some even have special modes to detect live wires.
