How to Find Lost Keys with a Metal Detector

How to Find Lost Keys with a Metal Detector

Have you lost your keys and spent hours looking for them only to come up empty-handed? You know how frustrating and anxiety-inducing it can be to realize your keys are missing. If you don't find them, it can cost hundreds of dollars to get them replaced.

But don't panic. With the help of a metal detector, you can find your lost keys. In this article, we'll first determine a search area. Next, we'll help you find a metal detector and adjust its settings. And we'll set you up for success with search tips and techniques.

Determine Your Search Area

When you've lost your keys, your first instinct may be to panic. Don't panic. Instead, remind yourself that your keys haven't grown legs and run off. Probably.

They are somewhere, likely close, and you can find them. First, let's determine your search area.

  • Put yourself (figuratively) in your own shoes when you lost your keys. What was on your mind? It's common to be running on autopilot when we're doing routine tasks, so anything you can remember specifically may lead you to the exact spot where you lost them.
  • Retrace the path you took, such as from your car to your front door. If you can't remember which way you went, check your usual routes. Mark an area around that path (or paths) with a reasonable buffer of 10 to 15' (3 to 4.5 m). Unless they were thrown (or grew legs), they won't be much further than that.

That path, plus your buffer zone, is your search area. Next, let's find a metal detector.

Rent a Metal Detector

To find your lost keys with a metal detector, you'll first need a metal detector. Before renting one, check with family and friends to see if anyone you know has one available that you can borrow.

If that doesn't pan out, renting a metal detector is your next best option.

3 Features to Look For in a Metal Detector Rental

Discrimination — This is one of the most important features. Discrimination allows you to ignore the types of metal that you aren't looking for, so that you can focus on the kinds that you are trying to find.

For instance, let's say you're looking for a silver ring in part of your yard where you know there are lots of small steel screws. If you're using a metal detector without the ability to differentiate between silver and steel, it'll be like finding a needle in a haystack. But with that ability? A piece of cake.

Adjustable Sensitivity — Discrimination is helpful, but just one third of what you need to find your keys. Paired with adjustable sensitivity, you can not only ignore metals by type, but also ignore metals by depth.

Many cheap metal detectors (under $100) have a fixed sensitivity setting. Some, like the Bounty Hunter Tracker IV, claim to have adjustable sensitivity, but in practice, it's a knob with two settings: High and Off. You need more options than none.

Why? It's a common misconception that the higher you set the sensitivity, the easier it will be to detect something, but in reality, that's not how it works. As you increase sensitivity, you can detect deeper and smaller objects, which is great if you're hunting for buried treasure. But when you're looking for your keys, or a ring, or something else sitting on the surface, you need to set the sensitivity as low as possible.

This way, you ignore the pipes, wires, and other metal hiding underground. And, the discrimination system does more of what you want it to do job when it's not dealing with metals that are in the right range but 8" (20 cm) below the surface.

Depth Indicator — The last piece of this detector trifecta is a depth indicator, or some way of telling how far the metal you've detected is from the end of the machine.

Let's say you've got your discrimination pattern set just right, and the sensitivity as low as it can go, and you've been swinging your metal detector for a while, coming up with a lot of nothing. But then—something! A ping. You throw the detector halfway across the yard in excitement, get on your hands and knees, caressing that luscious grass in search of your keys. But there's nothing there. What gives?

When you swing your detector back over that spot, this time you look at the depth indicator: it says something in the right range is there, but it's 4 to 6" (10 to 15 cm) down. *Someone's* keys might be down there, but they're not yours. Every time the detector pings, check that depth indicator, so you're not wasting your time on something underneath the ground, when you're looking for something on top of it.

Where to rent a metal detector

By our research, there are just a few companies in the United States that rent metal detectors with the features you need to find your keys. Prices nationwide range from $15 to $65 per day for a multi-purpose metal detector rental.

Some companies require cash-only deposits, which can be prohibitively expensive. These deposit fees range from $100 to $200.

What if there aren't any rentals near me?

If there aren't any metal detector rental options near you, another option is to hire a metal detector specialist to try to find your keys for you.

Most operate on a reward basis—they'll ask you to pay them based on what you think is fair for finding your keys. Many also charge a fee to travel to you, which usually starts at $25.

As a last resort, you could buy a metal detector. Good options include the Minelab Vanquish 440.

Adjust Settings

With a metal detector in hand, it's time to adjust the detector's settings. Some rental companies may adjust these settings for you, but most won't, so let's get into the details. We're assuming you have a Garrett ACE 300 or Minelab Vanquish 440, the most commonly available rental models.


First, let's adjust the sensitivity. The higher you set the sensitivity, the deeper you can go.

Since we're looking for keys lost on the surface, we don't need the metal detector to be finding the myriad of metal buried underground. So, let's set it to its lowest notch.

If you're searching in snow, however, you'll want to set the sensitivity higher, depending on the depth of the snow. A good rule of thumb is that for every inch (2.5 cm) of snow, you'll want to increase the sensitivity by one notch.

To do this, locate the pair of buttons that adjust the sensitivity.

Adjusting Sensitivity on the Garrett ACE 300

ACE 300 Controls

Immediately below the screen, at the center-top of the controls, you'll see the word SENSITIVITY printed above a set of and buttons.

Use the to decrease the sensitivity, and the to increase it. To find our lost keys in the grass, we'll need to set it to just one notch. Maybe two if we're feeling frisky.

Adjusting Sensitivity on the Minelab Vanquish 440

Vanquish 440 Controls

Immediately below the screen, at the center-top of the controls, you'll see a vaguely seashell-shaped icon printed above a set of and buttons, which corresponds with the identical on-screen icon that indicates Sensitivity.

Use the button to decrease sensitivity, and the button to increase it. To find lost keys, set it to two to three notches.


Setting a discrimination pattern for a set of keys can be a bit tricky. If you've just lost one key, that's one kind of metal. But when its multiple keys jumbled together on a ring, with a car fob (and maybe a bottle opener) thrown in the mix, the range of metals can expand dramatically.

House keys are made of brass (a mixture of copper and zinc), nickel, steel, or aluminum. Key rings are typically zinc-plated steel. Car keys are usually made of steel, while key fobs contain circuit boards and batteries, making them a lot like searching for a lost phone.

Because of this, we'll be a bit less discerning in our discrimination pattern than we would be if we were looking for a ring or something else that we know the exact composition of. Let's get adjusting.

Adjusting Discrimination on the Garrett ACE 300

  1. Press the or MODE buttons to cycle through the search modes. Stop when the circular outline is around Custom Mode.
  2. At the top-right of the controls, you'll see a set of and buttons labeled DISCRIM. These move a cursor left and right across the 12 segments of discrimination, and are what you'll use to set a discrimination pattern.
  3. Press the button until you reach the 11th segment, between 90 and 95.
  4. Below the and DISCRIM buttons is a / button. Press that to ignore the selected segment. You'll see a black rectangle that indicates the 11th segment is being detected will disappear.
  5. Repeat steps 3 and 4 for the 12th segment (between 95 and 99). In doing so, you've set a discrimination pattern that ignores the silver range, which is not in our lost keys.

Adjusting Discrimination on the Minelab Vanquish 440

  1. Press the button (on the right-hand side of the controls, next to the screen) repeatedly to cycle through the search modes. When you see a icon on the lower right side of the screen, stop. You've arrived at Custom Mode.
  2. Immediately below that icon, you'll see five white rectangles above a set of and buttons. These are what you'll use to set a discrimination pattern in a moment. The buttons move a cursor left and right across the 12 segments of discrimination.
  3. At the least, we know we're not looking for silver. Press the button to activate Edit Mode. You'll see Ed at the center of the screen. Keep pressing the button until you reach the 11th segment, between 30 and 35.
  4. Below the and buttons is a / button. Press that to ignore the selected segment. Repeat for the 12th segment to completely ignore the silver range.

On the Minelab Vanquish 440, a typical ring of house keys with a car fob will be detected at a range between 10 to 22. On the Garrett ACE 300, that same ring of keys will read as 40 to 85.

While we could specify just these ranges, the world isn't quite so black-and-white. The soil and terrain where you're searching can affect how the detector analyses its readings, and those numbers may not hold up where you are. So, keep the range in mind, and watch out for it, but take it with a grain of salt.

Now let's get searching.

How to Search for Lost Keys With a Metal Detector

Once you've adjusted the settings, it's time to start your search. Let's go over the basics.

Search Coil Orientation

First, keep the search coil (the roundish thing at the end of the detector) parallel with the ground. You'll want to hold the detector about an inch (2.5 cm) from the surface at most. By keeping it parallel, you'll be detecting with even coverage and depth throughout your search.

Sweeping the Detector

Since we need to keep the search coil parallel with the ground at all times, the way in which you sweep the detector from side to side as you walk across your search area needs to prioritize that above everything else.

We call it sweeping, but the motion is much more like stirring. Imagine stirring a pot of soup, or cookie dough. You want everything to be mixed evenly. Similarly, you want the detector to be evenly moving across the surface so that you can find your keys.

Practice the motion of moving the detector back and forth in a continuous semi-circle. There's a Goldilocks zone between moving too slow—and too fast—that will yield the best results. An ideal sweeping speed is around 3 to 4 seconds from side to side. If it feels comfortable while you're in the motion, you're at the right speed. Sweeping too slowly or too quickly lessens the likelihood of finding your keys.

Search in a Grid Pattern

With your sweeping technique down, how will you keep track of which parts of your search area you've thoroughly searched? We recommend taking advantage of a technique called a grid pattern (or gridding, for short).

Illustration of an imaginary grid overlaid onto a yard.

Imagine a grid laid over the search area, like a chess board. You can keep it imaginary, or bring it into the physical realm with rocks or marking flags to help you keep track of where you are and where you've been. The key to making the most of a grid pattern is to check each section of the grid from multiple directions. By doing this, you'll sweep close to 100% of the ground.

  1. As you sweep the detector from side to side, walk across your search area.
  2. Walk in a straight line from one edge of your grid to the other. In the image above, this would be the white lines.
  3. Then, turn 180º and search the same line from the opposite direction.
  4. Repeat this process until you’ve searched the extent of where you believe your keys to be. If you come up empty-handed, search over the same area again. But this time, do so at a 90º angle to the grid lines you’ve already swept across. In the image above, these are the pink lines.
  5. If you've still found nothing, try searching diagonally (yellow lines in the image). And if that doesn't yield success, expand your search area.

Tips for a Successful Search

  • Take your time — When searching for lost items on the surface, it's important to move slowly and methodically. Search from all directions.
  • Take breaks — Metal detecting is an exercise in itself, and can be exhausting both physically and mentally. When you feel yourself getting tired, take a break. Be kind to your mind and body.
  • Always check the depth — If the detector says it's deeper than 5" (12 cm), it's probably a pipe or other metal underground.

How To Prevent Losing Your Keys In The Future

If you’ve found your keys (or had them replaced), you'll want to avoid this situation in the future. Thankfully, you have options.

Short of piercing yourself with a keyring attached to a bungee cord, these days there are many small Bluetooth trackers that you can attach to your keyring. If you lose your keys again, you can remotely activate the tracker and pinpoint their location.

However, most Bluetooth trackers only work if you're within 40 to 200 feet (12 to 60 m) of them. And you'll need your phone with you to activate the alarm or other tracking feature.

If you have an iOS device like an iPhone or iPad, another alternative is Apple's AirTag tracker. They're very small, can be attached to almost anything, and use Apple's ultra-wide-band (UWB) technology and Apple's Find My network of billions of Apple devices to precisely pinpoint your lost item anywhere in the world, down to the inch.

About the Author

Gary Iverson

Gary Iverson is a staff writer at Metro Metal Detectors covering all things metal and metal-adjacent.

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