Garrett AT Pro
Garrett AT Pro Target ID Chart: What Each Number From 0 to 99 Means
Quick answer
The Garrett AT Pro reports targets on a 0 to 99 digital scale. Iron and nails sit roughly 0 to 40, foil and small gold 35 to 55, nickels around 54 to 60, pull tabs 55 to 70, zinc cents 70 to 78, copper cents and dimes 80 to 88, clad quarters 85 to 90 and halves 90 to 95.
A target ID is a conductivity ordering, not a lookup table. The Garrett AT Pro measures how readily a buried object carries an induced current at its single operating frequency, then maps that onto a number between 0 and 99. Iron sits at the bottom, small low-conductive metals such as foil and thin gold sit low, nickel and pull tabs occupy the middle, and copper and silver climb to the top. That ordering is physics and it does not change.
The exact number does change, constantly. Soil chemistry, moisture, depth, target orientation, corrosion, coil choice and firmware all shift a reading, and a coin standing on edge can read twenty points away from the same coin lying flat. Treat the bands below as where to expect a target, then confirm them in your own ground. The AT Pro depth chart covers the other half of that question, which is how far down the number stays trustworthy.
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Garrett AT Pro
The machine this chart describes, waterproof to 10 feet with 40 levels of iron discrimination and Garrett proportional audio.
Price was accurate when this page was compiled and changes often.
On this page
How do you read the AT Pro 0 to 99 scale?
Garrett splits the AT Pro display into a digital number and a segmented discrimination scale above it. The number is the useful part. Garrett publishes 40 levels of iron discrimination on this machine, which means the bottom of the scale is resolved finely enough to tell a small nail from a large one, and the top is compressed: everything from a copper cent to a silver dollar lives inside about fifteen points.
That compression matters. Below 40 you are usually looking at ferrous material and the number bounces. Between 40 and 70 you are in the zone where gold, aluminium and pull tabs overlap so badly that no machine can sort them by number alone, which is why jewellery hunters dig that band and coin hunters skip it. Above 78 the machine is stable and repeatable, and a clean, locked number from two directions is worth trusting.
What does each target read on a Garrett AT Pro?
These are the bands owners consistently report on the AT Pro at its single operating frequency, on land, with the stock 8.5 by 11 DD coil. They are starting expectations, not promises.
On a Garrett AT Pro, US nickels typically read 54 to 60, zinc cents 70 to 78, dimes 80 to 88 and clad quarters 85 to 90, with iron below 40 and every one of these bands moving several points with depth, soil and orientation.
| Target | Typical AT Pro ID | What moves the number |
|---|---|---|
| Small iron nail | 0 to 40 | Rusted or flattened iron can jump high and read as a good target from one direction |
| Steel bottle cap | 0 to 40, or 70 to 90 | A flattened cap mimics a coin. Check it from two directions and listen with Iron Audio |
| Aluminium foil, small scrap | 35 to 50 | Size dominates. A larger sheet of foil climbs into the pull tab band |
| Small gold ring, under 2 grams | 40 to 60 | Thin low-karat gold reads low and overlaps foil. There is no gold-only number |
| Larger gold ring, 5 grams or more | 55 to 75 | Mass and shape lift the reading. A wide band reads higher than a thin one |
| US nickel | 54 to 60 | One of the most stable readings on the machine and the best calibration target |
| Square pull tab | 55 to 65 | Sits on top of the small gold band, which is the central problem of park hunting |
| Ring pull, beaver tail | 60 to 70 | Corrosion pushes these around more than most trash |
| Zinc cent, post 1982 | 70 to 78 | Corroded zinc drops several points and can slip toward the tab band |
| Copper cent, pre 1982 | 80 to 86 | Stable when clean. Heavy patina lowers it slightly |
| US dime, clad or silver | 80 to 88 | Silver reads at the top of this band, clad at the bottom |
| US quarter, clad | 85 to 90 | The most repeatable high-conductor signal on the machine |
| US quarter, 90 percent silver | 88 to 92 | A point or two above clad, not a reliable way to tell them apart |
| Half dollar, silver dollar | 90 to 95 | Large silver reads near the top of the scale, as physics predicts |
| Large copper, buckle or button back | 85 to 95 | Surface area, not precious metal content, is driving this reading |
| Can slaw, shredded aluminium | 60 to 85, erratic | Broken and jumping numbers with no repeatability are usually mangled aluminium |
Bands reflect the ranges AT Pro owners consistently report at moderate depth in mild soil with the stock coil. Garrett publishes the 0 to 99 scale and the 40 iron discrimination levels; the per-target bands are field convention, not a manufacturer specification.
Why does the same coin read two different numbers?
Six things move a target ID, and they stack. Depth is the largest: as a coin approaches the edge of detection the signal weakens, the number wanders and eventually the machine averages it downward. Soil mineralisation is next, and a hot red clay or black sand site will pull readings down and broaden them. Moisture changes conductivity, so the same patch reads differently after rain. Orientation matters because a coin on edge presents a fraction of its surface to the coil. Corrosion changes the metal itself. Finally, adjacent iron drags a good target's number down, which is the whole reason for small coils and fast recovery.
The practical consequence is that a single number is never a decision. A repeatable number from two directions at a sensible depth is a decision. If the machine gives you 82 one way and 41 the other way, that is iron or it is a good target masked by iron, and the only way to find out is to dig it or to switch to the smaller coil and try again.
How do you build a target ID chart for your own soil?
- Gather known targets. Collect a nickel, a zinc cent, a copper cent, a dime, a quarter, a pull tab, a piece of foil, a small nail and a bottle cap. Use targets in the condition you actually dig, not mint coins.
- Bury them at measured depths. Dig a plot in your own ground and bury one set at two inches, one at four, one at six and one at eight. Mark each position and let the ground settle for a few weeks so the soil halo forms.
- Ground balance where you buried them. Run the AT Pro through its ground balance procedure on that exact patch, with the sensitivity you normally hunt at, not at maximum.
- Record what the machine says. Sweep each target from two directions and write down the number, the tone and whether the reading repeats. Note the numbers that surprise you, because those are the ones costing you finds.
- Repeat when conditions change. Read the plot again after heavy rain and after a dry spell. The gap between those two readings is the honest error bar on every number in this chart.
Which readings should you dig on the AT Pro?
For old coins in a park, a repeatable signal above 78 is worth a hole almost every time, and a solid 54 to 60 is worth one too because that is where nickels and some gold live. For jewellery, you have to accept the 45 to 75 band and the pull tabs that come with it, which is slow, dirty work and the reason people carry the Garrett Pro-Pointer AT rather than widening every hole. For relics, the number is almost irrelevant and the tone carries the information, which is covered on the AT Pro tone profiles page.
If you are stepping up from an ACE machine, the numbers are close but not identical, and the Garrett target ID comparison lines the scales up. Keep a written record of what you dug against what the machine said. After a season, that record is worth more than any chart on the internet.
Sources
- Garrett AT Pro owner's manual
- Garrett AT Pro published specification sheet
- Garrett AT Pro Amazon listing feature bullets, including the 40 level iron discrimination figure
Frequently asked questions
What number does silver read on a Garrett AT Pro?
Silver coins read at the top of the scale because silver is highly conductive. A silver dime typically falls around 84 to 88, a silver quarter around 88 to 92, and a half dollar or dollar around 90 to 95. Clad coins read only a point or two lower, so the number alone will not tell you silver from clad. Depth, soil and orientation move all of these figures.
Why does my AT Pro read 80 on a bottle cap?
A steel crown cap is ferrous, but its flat disc shape produces an eddy current pattern close to a coin, so the machine can report a high conductive number from one sweep direction. Sweeping from a second direction usually breaks the illusion and drops the number into the iron range. Iron Audio makes the same check audible, which is why many AT Pro owners leave it switched on in bottle cap country.
Does the AT Pro have a separate number for gold?
No detector does, and any chart promising one is selling something. Gold jewellery spans roughly 40 to 75 on the AT Pro depending on mass, karat and shape, which is the same band occupied by foil, pull tabs and ring pulls. The only honest approach is to decide in advance whether you are hunting jewellery, dig that whole band, and accept a high trash ratio for it.
How much does mineralised soil shift AT Pro target IDs?
Enough to matter. In heavily mineralised ground, readings typically drift downward and become less repeatable, and the effect grows with depth. A deep dime that reads 84 in mild soil can read in the seventies and bounce in hot ground. Ground balancing before each session reduces the drift but does not remove it, which is exactly why a buried test plot in your own soil is worth the effort.
Is the AT Pro target ID the same as the AT Max?
Both use a 0 to 99 scale and the target ordering is the same, but the machines run at different frequencies, so individual numbers can differ by a few points on the same buried object. The AT Max tends to be a little livelier on small low conductors. Compare them on the AT Max chart rather than assuming a number transfers between the two machines.
Researched, not professional advice. This page is compiled from published specifications, manuals and owner-review consensus, not hands-on testing. Target ID numbers, depth figures and settings vary with soil chemistry, moisture, target size, depth, orientation and firmware version, so treat every figure here as a starting point and verify it against your own machine's manual and your own ground. As an Amazon Associate we earn from qualifying purchases.