Metal detector target ID explained

What the number represents

Target ID is the detector's estimate of a target's electrical response, commonly displayed as a numeric value or a highlighted discrimination segment. Manufacturers often arrange ferrous responses towards one end of the scale and more conductive non-ferrous responses towards the other. That arrangement helps comparison within a detector; it is not a universal material analyser.

For example, the Minelab X-TERRA PRO manual uses -19 to 99, with -19 to 0 described as ferrous. Garrett's ACE 300 uses a 0–99 numeric conductivity scale. Nokta's SCORE uses 60 target IDs. These different systems are why a number quoted in a video or forum post is useful only when the detector model and settings match.

Why the same coin can show different IDs

A clean modern coin lying flat and shallow in neutral soil is the easy laboratory case. Real permissions introduce variables:

• A coin on edge presents less surface to the field and may give a weaker or less stable response.
• Depth reduces signal strength, so the display may jump or fail to settle.
• Corrosion and soil attachment change the electrical response of an older object.
• Iron close to a non-ferrous target can pull the ID down, clip the tone or create a mixed response.
• Mineralised ground and conductive salt add their own signal.
• A large piece of iron can produce a high response at the edge of the coil.

The X-TERRA PRO manual explicitly notes that some non-ferrous targets can display a negative ID when adjacent to ferrous metal. That is a practical warning against rejecting every uncertain negative response on an iron-rich site.

Five clues to use together

1. Repeatability

Sweep at a consistent height and speed. A promising isolated target commonly repeats in roughly the same place. A response that only appears at the far edge of the coil or disappears on a controlled return sweep deserves caution.

2. A second direction

Turn approximately 90 degrees and sweep again. A coin-like target may remain compact and repeatable; long iron can produce a different position or broken response. This is a clue, not a guarantee—nearby objects and target angle can still confuse the pattern.

3. Tone shape

Listen to where the sound begins and ends. A compact response has a different footprint from an elongated can or wire. On detectors with several tones, listen for consistency rather than chasing the highest pitch alone.

4. Depth indication

Depth meters are normally calibrated around coin-sized targets. Large metal can appear shallower than it is, while a tiny target may appear deeper. Use the indicator to plan recovery, not as a measurement certificate.

5. Pinpoint footprint

Pinpoint mode or short crossed sweeps help estimate target size and centre. A broad response can indicate a large or shallow object. Accurate centring also lets you dig beside the likely target instead of through it.

Build a UK test set

Use ordinary items you are legally entitled to handle: current copper-plated steel coins, cupro-nickel coins, aluminium foil, ring-pulls, bottle caps, an iron nail and a brass object. Place one item at a time on clean ground and pass the coil at several heights. Then place a coin near the nail and watch how the response changes.

Do not memorise a single value. Record a band, tone and behaviour: for example, “stable from two directions when shallow; becomes less settled beside iron”. Repeat the exercise after changing frequency or mode. This creates a notebook for your machine rather than a borrowed chart.

Target ID and UK coins

British coinage spans different alloys, sizes, thicknesses, wear and corrosion states. Modern denominations can overlap rubbish, and historic coins do not remain in neat material groups. Thin hammered silver, small fragments, copper-alloy coins and lead tokens can appear in ranges that aggressive discrimination removes.

If coin hunting is the main aim, read our best metal detectors for coins for ground-specific choices. The important buying difference is not the number of digits on the display; it is how consistently the machine reports difficult targets in your normal soil and how clearly its audio communicates uncertainty.

When discrimination hides good targets

Discrimination suppresses chosen target ranges. That can reduce fatigue in modern litter, but it also creates silence where desirable and unwanted objects overlap. Begin with a conservative factory programme and only reject a range after testing what else occupies it.

On an archaeological permission, the landowner or project lead may expect broad recovery and recording rather than selective coin shooting. Agree the search and recording method first. See England and Wales permissions and how to get permission.

A reliable decision routine

When a signal appears, slow down without scrubbing the coil. Make two or three consistent passes, note the ID band, turn and repeat, then estimate the footprint. Recover if the signal fits the permission and your agreed method. Log surprising targets so the machine teaches you where your assumptions failed.

Target ID becomes valuable when it supports a repeatable process. Used as an object label, it encourages false confidence; used alongside audio and careful recovery, it helps you make more deliberate decisions.

Continue learning

Practise the correct sweep technique, compare multi-frequency and single-frequency detectors, and use a pinpointer only after the full-size detector has narrowed the recovery area.