Hitting a signal is only half the job. Knowing what your detector is telling you is what separates a lucky beginner from a confident detectorist. Anyone can swing a coil over a hot spot, but reading the results correctly is what saves you from digging twenty bottle caps before you find a single ring.
Every detector communicates through some combination of sound, numbers, and, on more advanced units, visual depth and composition data. This guide from our team at Garrett breaks down the three universal readouts you’ll find on almost any machine, how those readouts translate across different models, and how higher-end technology adds another layer of precision to the process.
Key Takeaways
- Metal detectors communicate through up to three signals – tone, Target ID, and depth – though simple models may only beep, high-end pulse detectors often skip Target ID, and not all show depth.
- Low or growling tones usually point to iron and nails, mid tones can mean foil and pull tabs but also gold, many types of jewelry, and US nickels, and high, crisp tones typically signal copper, brass, or silver.
- Many of today’s detectors use a 0 to 99 Target ID scale, though some add negative numbers for ferrous targets. Generally, the low range points to iron and foil, the mid range to aluminum or gold jewelry, and the high range to coins and brass relics.
- Mineralized soil and iron-heavy or trashy ground can distort tones and VDI numbers, which is why ground balancing before each hunt is essential for accurate readings.
- Following a simple sequence, listening to the tone, checking the Target ID, noting the depth, and using a pinpointer before digging, works for detectors at any level of technology.
- Garrett’s advanced Vortex VX7 and VX9 detectors go beyond a single VDI number with dual ferrous and non-ferrous composition scales, helping cut through guesswork on tricky targets.
The Three Signals Most Metal Detectors Give You
Nearly all high-quality modern metal detectors used for coin hunting talk to you through the same three channels: sound, a numeric ID, and depth. Learning to read all three together, instead of relying on just one, is the fastest way to become accurate in the field. Once you understand how these three signals work together, you can start narrowing down what is in the ground before you ever lift a shovel.
Audio Tones
Tone is the first clue your detector gives you, and it comes through instantly on every swing, assuming the target isn’t discriminated out. A low or growling tone usually points to ferrous metal such as iron and nails. A mid tone can mean foil and pull tabs, but also gold, many types of jewelry, and US nickels. A high, crisp tone is generally associated with higher conductors like copper, brass, or silver, which covers most coins and higher quality jewelry.
The consistency of the tone matters just as much as its pitch. A clear, steady tone on repeated swings usually means you are looking at a solid, single target. A broken or choppy signal often means multiple objects or trash are layered together in that spot.
| Tone Type | Pitch | Likely Target |
| Low or growling | Deep | Iron, nails, steel |
| Mid tone | Medium | Foil, pull tabs, some gold, US nickels, thin jewelry |
| High tone | Sharp | Copper, brass, silver coins, jewelry |
Target ID (VDI) Numbers
VDI stands for Visual Discrimination Indicator, and most detectors display it as a number somewhere on a 0 to 99 scale. This number gives you a second, more specific read on what is likely buried, backing up whatever the tone already told you and helping with target discrimination in the field.
The low end of the scale, roughly 0 to 35, is solidly ferrous ground: iron and nails. Once you climb past that, you’re in non-ferrous territory, where the good stuff starts to show up. It’s worth resisting the urge to treat each range as a fixed list of “this metal equals this number,” though. VDI reflects conductivity and size together, not metal type alone, so the same object can change depending on how big it is.
That’s why the 40s through 60s are where a lot of exciting finds turn up, foil and pull tabs, sure, but also rings, chains, and other gold jewelry in average sizes. A larger or chunkier piece, like a thick gold ring, can climb even higher. On the high end, from about 60 to 99, you’re often looking at old copper and silver coins, brass relics, and other substantial non-ferrous finds worth digging for. Checking the VDI number even when you feel confident about the tone is a smart habit that helps you zero in on the treasure and know what you’re about to pull out of the ground.
| VDI Range | Typical Targets |
| 0 to 40 | Iron, nails, thin coins |
| 40 to 60 | Rings, chains, gold jewelry |
| 60 to 99 | Copper and silver coins, brass relics |
Depth Indicators
Most detectors also show a depth reading, often displayed in inches such as 2, 4, 6, or 8 plus. This gauge estimates how deep the target sits, which helps you decide how much digging effort to expect before you even start.
Deeper targets tend to sound fainter and broader across the swing, since the signal has to pass through more soil to reach the coil. A helpful habit before digging anything is using a pinpointer, which narrows the signal down to the exact center of the target and saves you from digging a hole that is bigger than it needs to be. This one habit alone is one of the most useful metal detecting tips for keeping your holes small and your recovery times fast.
One More Factor That Affects Every Reading: Ground Conditions
Tone, VDI, and depth are only accurate when the ground itself is not interfering with the signal. Mineralized soil and saltwater beaches are notorious for distorting both tone and VDI numbers, sometimes making a detector chatter or give inconsistent readings even over open ground, which is also why detecting on the beach takes a slightly different approach than detecting inland.
That’s a separate issue from trashy or iron-rich sites, where nearby junk can mask or blend with a better target sitting close by, tricking a detector into making treasure sound like junk (or vice versa). No amount of ground balancing will sort that out, since it’s a target-separation problem, not a mineralization problem.
Where ground balancing does matter is calibrating your detector to the mineral content of the soil at that specific site. Doing this before every hunt is not optional if you want your tones and numbers to stay accurate for the rest of the hunt.
Not All Detectors Read the Same Way: Comparing Entry Level vs. Advanced Machines
Most modern quality metal detectors have some form of tone, number, and depth system, but how much information you actually get, and how clearly it is presented, depends heavily on your detector’s tier. A beginner machine and a top tier machine can be standing over the exact same coin and give you very different amounts of detail. Understanding where your detector falls on this spectrum helps set realistic expectations for how precise your readings will be.
Basic and Older Detectors
Older detectors often rely on sound alone, with no visual indication at all of what might be buried. Entry-level modern detectors improved on this by adding simple graphic icons, such as a coin, a ring, or a trash can, instead of a numeric Target ID.
- Older detectors and even some specialty detectors (like pulse induction gold machines) provide audio tone only, with no screen or visual reference
- Some inexpensive beginner detectors use playful, basic icons like coin, ring, or trash symbols
- Icon-based systems group many different targets into a few broad categories
- This grouping means more guesswork is left to the user compared to a numeric readout
Mid-Range Modern Detectors (Most of the Market)
Most quality detectors released in the last several years include a digital Target ID number paired with some form of visual depth indicator. This combination has become the baseline expectation for anyone buying a modern detector today.
At this tier, this visual Target ID system looks similar between competing brands. Most mid-range machines will give you a comparable level of tone, VDI, and depth information, which means the buying decision often comes down to build quality, coil size, or price rather than the core readout system.
Advanced Detectors: Beyond a Single VDI Number
Higher-end machines go a step further with dual ferrous and non-ferrous composition scales, giving a more precise read on metal type than a single VDI number alone can provide. Instead of one number trying to describe a target, you get two separate readings that together paint a clearer picture of what is in the ground.
This extra layer matters most in tricky field situations, such as iron-masked targets or layered metals, where a single-scale machine might misread the signal entirely. Dual-scale readouts like this are generally reserved for higher-end units across the industry, such as Garrett’s Vortex VX7 and VX9.
Putting It All Together: A Simple Framework for Reading Any Detector
Once you understand what each signal means on its own, the process of reading any detector comes down to a simple, repeatable sequence.
- Listen to the tone first
- Check the Target ID number to confirm what the tone suggested
- Note the depth reading to gauge how much digging is ahead
- Use a pinpointer to help speed the recovery of your target
- Factor in ground conditions and mineralization, since they can change any of the readings above
This framework scales from the most basic machine to the most advanced one on the market, and it works just as well at good metal detecting locations as it does in your own backyard. Higher-end detectors don’t change the process, they just give you more information at each step, so you can make sharper, more confident dig decisions.
Frequently Asked Questions
What does a double beep or broken signal mean?
A double beep or broken signal usually means there is more than one target close together, that trash is mixed in with a better item, or there is an extremely shallow or surface-level target. It can also happen in mineralized or trashy ground where the signal is not clean. Slowing down your swing speed over that spot can often help separate the individual signals.
Can Target ID numbers vary between detector brands for the same object?
Yes, VDI numbers are not standardized across manufacturers, so the same coin can read slightly differently on two different types of metal detectors. The general low, mid, and high ranges still hold true, but exact numbers should be treated as a guide specific to your own machine rather than a universal standard.
Do I need a high-end detector to read signals accurately?
It depends on how much target information you need. Entry-level and mid-range detectors give a usable tone and VDI reading for many targets, including when you’re searching for a ring or a common coin. But “usable” isn’t the same as “as much information as possible.”
A detector like our VX9 model tells you whether even a single, isolated signal is ferrous or non-ferrous, which budget machines typically can’t do. That’s extra confidence on every target, not just a benefit for tough, iron-masked, or layered situations.
Why does my detector read differently in different soil?
Mineral content in soil affects how the detector’s signal travels and returns, which can change tones and VDI numbers even for the same object. This is why ground balancing before each hunt is so important, since it adjusts your detector to that specific soil and keeps your readings as consistent as possible.
Choosing the Right Metal Detector for Your Search
At Garrett, we’re committed to pairing industry-leading detection technology with genuinely accessible price points, making advanced performance available at nearly every level. The two detectors below show how that commitment plays out across different feature sets, helping you find the right fit for your search style.
Garrett Vortex VX7
The Vortex VX7 brings multi-frequency detecting to intermediate users through a waterproof, feature-rich design built for versatility in the field.
- Multi-dimensional multi-frequency (MD-MF) technology with four frequency options, including Multi-Frequency and Multi-Salt modes
- Five search modes plus Pinpoint, covering everything from coin hunting to beach detecting
- Two-tier Target ID scale with digital 0–99 values, 5-tone audio feedback, and 175-point ground balance resolution
- Fully submersible to 16 feet, with a 15-hour rechargeable battery and Z-Lynk wireless compatibility
With its blend of waterproof durability, multi-frequency versatility, and software upgradeability, the VX7 makes advanced detecting technology approachable without asking users to outgrow their machine.
Garrett Vortex VX9
The Vortex VX9 extends that same multi-frequency foundation into a professional-grade tool built for detectorists who want maximum control and precision.
- Seven frequency options, including five single frequencies plus Standard Multi and Multi-Salt simultaneous modes
- Seven search modes plus Fast Mode and Pinpoint, offering more targeting flexibility than the VX7
- Three-tiered MD-MF Target ID scale distinguishing ferrous, non-ferrous, and iron properties with adjustable recovery speed
- Fully submersible to 16 feet, with a 15-hour rechargeable battery and built-in Z-Lynk wireless audio
By layering additional frequencies, modes, and target discrimination on top of the same rugged, waterproof platform, the VX9 illustrates just how far multi-frequency detection can be pushed for detectorists chasing the highest level of accuracy.
Understanding How to Read a Metal Detector
Reading a metal detector is a learnable skill built on three simple layers: tone, Target ID number, and depth. Once you get comfortable checking all three together, and accounting for ground conditions along the way, digging becomes far less about luck and far more about informed decisions.
As detectorists gain experience, many choose to upgrade to a unit with dual-scale composition readings, like our Vortex models at Garrett, to reduce guesswork on tricky or borderline finds. Whatever machine you use, the fundamentals in this guide will carry over and keep improving your accuracy in the field.
Still hunting for the detector that matches how you actually dig? Whether you’re chasing deep silver, working iron-heavy sites, or just want a machine that matches your skill level, reach out to us and we’ll help you find the right fit.