It’s the question every new detectorist asks, and the honest answer is “it depends”. A typical hobby detector will find a coin-sized object somewhere in the top 15–25cm of soil in reasonable conditions, and larger objects deeper. But the depth you actually get depends far more on the target and the ground than on the detector.
The short answer
- Coin-sized objects: roughly 15–25cm with a good hobby detector in decent conditions. Less in wet, mineralised soil or with a cheap detector.
- Larger objects, such as a pot or a big lump of iron: deeper, sometimes a metre or more for very large objects.
- Tiny objects, such as small gold or thin hammered coins: often only a few centimetres.
- Depth claims on the box are usually measured in ideal conditions, in air or in a test bed, and are rarely achieved in a real UK field.
What affects detecting depth
| Factor | Effect on depth |
|---|---|
| Target size | The biggest factor. A larger surface area is detected much deeper |
| Target shape and angle | A coin lying flat is easier to detect than one on its edge |
| Type of metal | Silver and copper are easier to detect than small or thin gold and many alloys |
| Coil size | Larger coils generally go a little deeper on bigger targets, but are worse at separating targets in rubbish |
| Ground mineralisation | Wet, salty or iron-rich ground reduces depth, sometimes a lot |
| Detector technology | Multi-frequency detectors hold their depth better on difficult ground |
| Settings | Sensitivity turned down to stop chatter means less depth. Discrimination can also cost depth |
| Swing | Keeping the coil low, level and overlapping each sweep matters more than most people think |
Why UK ground matters
Much British farmland is wet clay, and many beaches are wet salt sand. Both are “noisy” to a detector. To stop the chatter, you have to turn the sensitivity down, and that costs depth. That’s why multi-frequency detectors, such as the Minelab Vanquish range, are so popular in the UK. They stay stable on difficult ground without losing as much sensitivity.
Where most finds actually are
On ploughed farmland, most finds come from the plough soil, the top layer that gets turned over every year, which is typically about 25–30cm deep. Ploughing brings objects up within reach of a detector each season, which is one reason farmland keeps producing finds year after year.
Below the plough soil, you may be into undisturbed archaeology. The Code of Practice for Responsible Metal Detecting in England and Wales asks detectorists to try not to damage these deposits, and to seek expert help if they find something large below the plough soil or a concentration of finds. See our guide to what to do if you find treasure.
How to get more depth
- Swing low and slow. Keep the coil parallel to and just above the ground, and overlap each sweep.
- Use the highest stable sensitivity. Turn it up until the detector gets noisy, then back it off a notch.
- Dig iffy signals. Faint, deep signals are often the older finds.
- Consider a larger coil for open fields and beaches, such as the 12-inch coil on the Vanquish 560 or 540.
- Pick your moment. Damp soil often gives better signals than bone-dry ground. See the best time of year for detecting.
For more depth on open fields: Minelab Vanquish 560 (about £449)
The top Vanquish combines Multi-IQ multi-frequency, which holds depth on wet UK ground, with a larger 12-inch V12X coil that covers more ground and reaches a little deeper on bigger targets. It's fully waterproof (IP68) and weighs about 1.3kg. It's rated 4.6 stars from its first 15 Amazon UK reviews.
Learn the technique: Advanced Detecting by John Lynn and Greg Payne (about £18)
A UK book on improving your detecting technique and finds rate, covering settings, swing and reading signals. It's rated 4.6 stars from 100 reviews. For a beginner's introduction, Metal Detecting: All You Need to Know to Get Started (about £12) is rated 4.6 stars from 332 reviews. As an Amazon Associate we earn from qualifying purchases.
Frequently asked questions
How deep can a cheap metal detector go? Usually a few centimetres less than a good one on coin-sized targets, and much less on mineralised ground.
Does a bigger coil always go deeper? On larger targets in open ground, generally yes. On small targets in rubbish-filled ground, a smaller coil often finds more, because it separates targets better.
Can a metal detector find gold deep underground? Small gold is one of the hardest targets to detect, even near the surface. Large gold objects are detected like any other large target.
How deep can a pinpointer detect? Only a few centimetres. It’s for finding the exact spot in a hole, not for searching. See our pinpointer guide.