A metal detector's target ID is a number, usually on a 0 to 99 scale (or -9 to 40 on many Minelab machines), that estimates how conductive a buried object is. Low numbers mean iron, the middle of the scale holds gold, nickels, foil and pull tabs, and the high end is where copper and silver coins read.
That is the short answer. The longer answer is that the number is an educated guess, not a label, and the hunters who dig the most keepers are the ones who know when to trust it and when to dig anyway. Below we cover what the number measures, how each brand's scale works, a target ID chart for common finds, and a repeatable routine for reading a signal before you put a shovel in the ground.
What a Target ID Number Actually Measures
When your coil's magnetic field hits a piece of metal, the metal answers back with a small field of its own. The detector measures how much that returned signal is delayed (the phase shift) and turns that delay into a number. That number is the target ID, sometimes called the VDI (visual discrimination indicator).
Two things drive the reading:
- Conductivity. Silver and copper conduct well and read high. Aluminum, brass, gold alloys and nickel sit in the middle. Iron is ferrous and reads at the bottom of the scale.
- Size and shape. A bigger object of the same metal reads higher. A large aluminum can will read up with the silver coins, while a thin gold chain can read down near foil.
That second point is why the number can never tell you "this is gold." It tells you roughly where the object falls on a conductivity scale, and plenty of different objects share the same spot.
Target ID Scales by Brand
Every manufacturer draws its own scale, so a "25" on one machine means something completely different on another. Here is how the most common lines are laid out.
| Brand and models | Scale | Where iron reads |
|---|---|---|
| Garrett ACE series, AT Pro, AT Max, Apex | 0 to 99 | Roughly 0 to 35 or 40 |
| Minelab Equinox, Vanquish, X-Terra Pro | -9 to 40 | -9 to 0 (negative numbers) |
| XP Deus, Deus II, ORX | 0 to 99 | Low numbers, cutoff set by your iron tone break |
| Nokta Simplex, Legend, Score series | 0 to 99 | Roughly 0 to 15, varies by model |
| Fisher and Teknetics | 0 to 99 | Low numbers, roughly the bottom third |
If your machine is not listed, the owner's manual will show the scale and the default iron cutoff. Learn that one boundary first. Knowing where iron stops is more useful than memorizing any coin number.
Metal Detector Target ID Chart
These are typical readings for common US targets in average soil at moderate depth. Use them as a starting point, then correct them with your own machine in your own dirt (more on that below).
| Target | 0 to 99 scale (Garrett style) | 40-point scale (Minelab) |
|---|---|---|
| Nails, bottle caps, rusty iron | 0 to 35 | -9 to 0 |
| Aluminum foil, small scraps | 40 to 50 | 1 to 5 |
| Small gold rings, chains, earrings | 40 to 60 | 3 to 12 |
| US nickel | 55 to 60 | 12 to 13 |
| Pull tabs | 55 to 70 | 10 to 17 |
| Larger gold rings, class rings | 60 to 75 | 12 to 20 |
| Zinc penny (1983 and newer) | 78 to 82 | 19 to 22 |
| Copper penny, clad dime | 84 to 87 | 25 to 27 |
| Clad quarter | 87 to 90 | 28 to 30 |
| Silver dime or quarter | 86 to 92 | 26 to 32 |
| Silver half or dollar | 90 to 99 | 32 to 38 |
Look at the gold rows next to the pull tab row. They overlap almost completely. There is no setting and no number that separates a gold wedding band from a beaver tail tab, which is why jewelry hunters dig trash and coin hunters who discriminate out the middle of the scale rarely find gold.
Listen to the Tones, Not Just the Screen
Most modern detectors split the ID scale into tone regions. Iron gives a low grunt, the middle gives a mid tone, and high conductors give a high, clean tone. The point where one tone changes to the next is the tone break, and on most machines you can move it.
Experienced hunters read tones first and glance at the screen second, for a few reasons:
- You hear every pass of the coil. You only see the screen when you look down.
- A good target gives a repeatable tone in both directions. A target that chirps high one way and grunts the other is usually iron or a bent piece of junk.
- A faint, deep coin often shows a jumpy number but a steady tone. The audio holds up at depth better than the display does.
This is where a decent pair of headphones earns its money. The built-in speaker on most detectors blurs quiet, deep signals and short iron blips together, and wind or traffic covers the rest. A set from our metal detector headphones collection lets you hear the difference between a clean high tone and a high tone with an iron "grunt" hiding underneath it, and that difference decides a lot of digs.
Why Your Target ID Numbers Jump Around
A number that bounces between two values is normal. A number that bounces across half the scale is telling you something. The usual causes:
- Depth. The deeper the target, the weaker the signal and the less stable the ID. Deep coins often read a few points low, and very deep targets can bounce so much they look like trash.
- Ground mineralization. Hot soil, black sand, red clay and wet salt all add their own signal and drag the number around. Salt water in particular pushes readings toward the middle of the scale.
- Nearby iron. A coin lying next to a nail can read as iron, as a mixed signal, or as nothing at all. This is called iron masking, and it hides a lot of old coins in old yards.
- Orientation. A coin standing on edge reads lower and less steadily than one lying flat.
- Sweep speed. Swinging too fast gives the detector less time to process the signal. Slow down on anything interesting.
- Electrical interference. Power lines, invisible fences and other detectors nearby can add chatter and false numbers. Run a noise cancel if your machine has one.
Ground and depth problems are where multi-frequency detectors make the biggest difference. By transmitting several frequencies at once, they can hold a steadier ID in mineralized soil and at the beach, where single-frequency machines tend to bounce or go quiet. If your local ground is hot or you split time between the park and the surf, look at the multi-frequency metal detectors we carry.
How to Read a Signal, Step by Step
Here is the routine we use in the field. It takes about ten seconds per target once it becomes habit.
- Sweep over it a few times. Keep the coil flat and low, and note the number and tone on each pass. You are looking for repeatability, not one good reading.
- Turn 90 degrees and sweep again. Walk a quarter turn around the target and sweep across it from the new direction. A good target holds its ID from both angles. Iron and junk usually fall apart.
- Check the depth reading. A shallow target with a jumpy ID is suspicious. A deep target with a jumpy ID may just be deep.
- Run an iron check. Lift the coil a few inches and sweep again, or switch on your iron audio or ferrous indicator. Flat iron like bottle caps often gives a high tone at ground level but reveals itself when you lift the coil.
- Decide. If the number is steady in the range you are hunting and the tone is clean both ways, dig. If you are unsure and the site is productive, dig it too. Nobody learns their machine by walking past signals.
- Pinpoint and recover. Use your detector's pinpoint mode to mark the center, cut a neat plug, then use a handheld pinpointer to find the target in the hole or the plug.
That last step matters more than most beginners expect. A handheld pinpointer cuts recovery time and saves your coin from shovel scratches. If you do not have one yet, the pinpointer collection covers every major brand and price point.
Build Your Own Target ID Chart
No published chart, including ours, will match your detector exactly. Coil size, settings, ground balance and your local soil all shift the numbers. The fix takes one afternoon:
- Gather a test set: a nail, a bottle cap, foil, a pull tab, a nickel, a zinc penny, a copper penny, a dime, a quarter, and any gold or silver jewelry you are willing to bury.
- Sweep each one on the surface of your yard and write down the ID.
- Bury each one 3 in, 6 in and 8 in deep in marked spots, and record the readings again.
- Bury a coin next to a nail and see how your machine handles it.
You now have a chart built for your detector, your settings and your ground, and you will know exactly how much a deep dime drifts on your machine. Redo it whenever you change coils or move to very different soil.
When to Ignore the Number
The target ID is a filter, and every filter throws out some good targets along with the bad. A few situations where the number should carry less weight:
- Hunting gold jewelry. Gold lives in the foil and pull tab range. If rings are the goal, dig the middle of the scale.
- Old home sites. Old coins surrounded by nails often give broken, mixed signals. A high tone mixed with iron in a trashy yard is worth a look.
- Relic hunting. Buttons, buckles and many relics are brass or lead and read in the middle of the scale with wide, jumpy numbers.
- Very deep signals. When the ID is too faint to stabilize, the tone and repeatability are all you have.
Choosing a Detector That Is Easy to Read
If you are still shopping, a clear display, adjustable tone breaks and a readable iron indicator make learning target IDs much faster. We break down the machines that do this best for new hunters in our best metal detectors for beginners guide, and you can compare every model side by side in our full metal detectors collection.
Target ID FAQ
What do the numbers on a metal detector mean?
The numbers are the target ID, an estimate of how conductive the object under the coil is. Low numbers indicate iron, mid-range numbers cover gold, nickel, foil and pull tabs, and high numbers point to copper and silver coins. The exact ranges depend on your brand's scale.
What is a good target ID on a metal detector?
It depends on what you are hunting. For coins on a 0 to 99 scale, steady readings in the 80s and 90s are the classic keepers. For gold jewelry, the best targets often read in the middle of the scale alongside pull tabs, so "good" there means steady and repeatable rather than high.
What target ID number is gold?
Gold has no single number. Small gold chains and thin rings read low near foil, and heavier rings read in the mid-range near nickels and pull tabs. On a 0 to 99 scale most gold falls between about 40 and 75, and on Minelab's 40-point scale between about 3 and 20.
What is VDI on a metal detector?
VDI stands for visual discrimination indicator. It is another name for the target ID number shown on the screen, and some manufacturers use the term interchangeably.
Can a metal detector tell what kind of metal it is?
Not directly. It can tell iron from non-iron fairly well and can estimate conductivity, but different metals and different sizes overlap on the scale. A large piece of aluminum and a silver dime can give the same number.
Why does my metal detector target ID keep changing?
Depth, mineralized soil, nearby iron, the target's angle in the ground, fast sweeping and electrical interference all make IDs bounce. Slow down, sweep from two directions and lift the coil to check for iron before deciding.
What does a negative target ID mean?
On Minelab machines like the Equinox, Vanquish and X-Terra Pro, negative numbers (from -9 to 0) mean the target is ferrous, so it is iron or steel. Other brands show iron as low positive numbers instead.
Does depth change the target ID?
Yes. Deeper targets return a weaker signal, so the ID tends to read a few points low and becomes less stable. Burying a few known coins at different depths is the best way to learn how much your detector drifts.
