"How deep does it go?" is the first question almost every buyer asks, and it is the question with the least useful single answer. Detection depth is not a fixed property of a detector. It is the outcome of four things interacting: the size of the target, the conductivity of the target, the mineralisation of the ground, and the coil you have fitted. Change any one and the same machine will give you a different number.
Why one machine gives many different depths
A detector does not sense metal. It senses the strength of the field returned by eddy currents in that metal. A large object presents more surface for those currents and returns a much stronger field, so it is detectable far deeper. A one-gram nugget and a large brass artefact at the same depth are, from the coil's point of view, not remotely the same problem.
This is why a manufacturer can honestly print "4 feet" for a machine that will not see a small nugget past 25 centimetres. Both statements are true — they simply describe different targets. When you read a depth specification, mentally append the phrase "on a large target in mild soil".
Rated depths across our catalogue
The figures below are the manufacturers' own, as published for each machine. They are useful for comparison between models, not as a promise about your ground.
| Machine | Rated depth | Category |
|---|---|---|
| Nokta FindX / Simplex Lite | 2 feet | Entry metal detector |
| Nokta Simplex Ultra / Score | 3 feet | Mid metal detector |
| Nokta The Legend | 4 feet | Multi-frequency |
| GoldXtra TGX Lite | 7–8 feet | Multi-system gold |
| GoldXtra TGX Pro Plus | 10–12 feet | Multi-system gold |
| Nokta Jeohunter 3D Dual System | 9–10 feet | 3D imaging |
| Nokta Deephunter 3D Pro | 10–14 feet | 3D imaging |
| Lorenz Deepmax Z2 | 14–15 feet | Deep-seeking PI |
| Multimax | 16–20 feet | Ground scanner |
| OKM EXP 6000 PRO+ | Down to 25 m in favourable ground | 3D ground scanner |
Read the deep figures carefully
Notice that the deepest numbers belong to imaging systems and deep-seeking pulse induction machines, not to conventional gold detectors. There is a reason for that, and it is not marketing. Those systems are built to find large masses and cavities — a buried chest, a void, a substantial ore body — and their depth ratings assume a target of that size. None of them will find a single small nugget at 20 feet. No machine will.
OKM's own specification is refreshingly explicit about this: "down to 25 m under favourable ground conditions". That qualifier is doing a great deal of work, and any honest dealer will tell you so.
What actually costs you depth in the field
Mineralisation — Iron-rich and salt-laden soil forces the detector to reject more signal, and rejected signal includes some of your target. This is the single largest factor in most Pakistani gold country.
Poor ground balance — A machine that has not been balanced to the ground it is standing on can lose a third of its usable depth. This is free performance most beginners never claim.
Sensitivity set too high — Running maximum sensitivity in noisy ground produces chatter, and operators then swing faster and miss the faint signals that matter.
Coil choice — A large coil buys depth on big targets and loses sensitivity on small ones. Fitting the wrong coil for the target is a common and expensive mistake.
Swing speed and overlap — A detector needs time over a target. Fast, wide swings with no overlap leave unsearched lanes between passes.
A realistic expectation
For small gold in mineralised ground, expect a good VLF or PI machine to work within the top 30 centimetres and to be excellent there. For coin and relic-sized targets in reasonable soil, 20 to 40 centimetres is a realistic working band for most quality detectors. Anything advertised well beyond that is either describing a large target, a benign test bed, or an imaging system solving a different problem.
The practical consequence: depth is rarely the specification that should decide your purchase. Sensitivity to your target size, stability in your soil, and how well you can operate the machine will find you more gold than an extra rated foot ever will.
