Which radiation a handheld detector actually picks up

A Geiger counter counts ionising radiation. HyperPhysics (Georgia State University) describes the tube as a wire inside a cylinder held at high voltage: a particle that ionises a few gas molecules sets off an avalanche of electrons, a pulse of current, and the counter turns each pulse into a click and a count. This detector's glass tube responds to beta particles, gamma rays and X-rays. It does not see alpha particles, which cannot get through the glass wall. The manufacturer gives an energy response of 48 keV to 1.5 MeV and a dose rate range of 0.01 µSv/h to 50 mSv/h.

Some devices sold as radiation meters measure something else entirely. Electromagnetic fields from power lines, Wi-Fi, microwave ovens and 5G phones are non-ionising: a Geiger tube does not register them, so this counter tells you nothing about EMF, microwaves or 5G. Nor is it a radon test: radon is measured as a concentration in indoor air with a radon measurement pack, available through UKHSA's UK Radon service, whose maps of radon Affected Areas show where testing is advised. It cannot test food or water either.

Geiger counter, scintillation detector or EMF meter?

Three kinds of device share the label radiation detector, and they are not interchangeable. A pocket Geiger counter with a glass tube counts beta, gamma and X-ray events and gives an indicative dose rate. A consumer scintillation counter uses a crystal instead of a gas tube and adds a spectrometer; according to public product sheets it is more sensitive to gamma than a Geiger tube of this size, an honest step up if gamma sensitivity is your priority. The low-cost 3 in 1 meters sold as radiation detectors are mostly EMF meters and do not count ionising radiation at all.

The price ranges in the table are orders of magnitude read on public UK listings on 28 September 2026, not quotes, and include VAT as displayed. Short-tube Geiger counters also exist; according to the maintainer of an open-source counter firmware, they are less sensitive to background than a J321-type tube. For uranium glass, granite or background radiation at home and on your travels, a glass-tube Geiger counter covers beta and gamma. EMF questions need a different instrument.

Radiation detector types compared (UK price ranges seen on public listings, 28 September 2026, VAT included)
Detector typeWhat it picks upTypical price range
Pocket Geiger counter with a glass GM tubeBeta, gamma and X-rays; no alphaAbout £37 to £81
Consumer scintillation counter with spectrometerGamma, more sensitively than a pocket Geiger tubeNot surveyed on UK listings
3 in 1 meter sold as a radiation detectorMostly electromagnetic fields (EMF), not ionising radiationAbout £13 to £28
Radon measurement packRadon concentration in indoor airNot surveyed; available through UKHSA's UK Radon service

What this detector shows on its 2.4-inch screen

The colour screen gives the real-time dose rate and the average dose rate in µSv/h, the count rate in CPM or CPS, and the cumulative dose in µSv. The main display shows either the figures or the dose-rate trend graph. A timed dose mode runs for a period you set, from 0 to 999 hours, and you can check the start date of the cumulative dose. Above its range, the screen shows 999 MAX. The cumulative dose, graphs, alarm history and thresholds are kept after the power goes off.

Two alarms watch the dose rate and the dose, each with its own adjustable threshold, and they alert by sound, flashing light or vibration. The menu comes in several languages and the particle click can be switched off. The built-in 1,800 mAh lithium-ion battery charges over USB-C and is not user-replaceable. Battery life depends on use: the manufacturer states 30 days or more in long-life mode, while an independent test found about 5 days in normal use. There is no Bluetooth and no phone app.

How to read it properly

Radioactive decay is random, so a single figure jumps about: let the counter run for several minutes and read the average dose rate or the trend graph. The reading takes time to settle on an object, and after a more active object it takes time to drop back to background. Background itself varies from place to place: the US EPA says it comes mostly from minerals in the soil, water and cosmic radiation, and rises with altitude. One independent test measured about 20 CPM at background with this type of tube.

On beta sources, read CPM. The tube has no beta shield, so the µSv/h figure runs high when beta particles reach it; the count rate is the tube's raw data. Never compare CPM between two different counters, because each tube responds differently. The same caution applies to public monitoring networks such as the EPA's RadNet in the United States, whose 140 air monitoring stations publish near real-time gamma readings: compare trends, not figures, since units, height and instruments differ. Every reading from this counter is indicative.

If a reading looks high: what to do and who to contact

This is a consumer radiation detector for general information only. It is not a calibrated measuring instrument, not personal protective equipment and not a radon test, and its readings are indicative. If you see an unusually high or persistent reading, move away from the source, do not handle the object and contact the competent authority: in the UK, the UK Health Security Agency (UKHSA) or your local authority, who can advise on what to do next. Do not rely on the counter to decide whether an object or a place is fine. In an emergency, call 999.

Official figures give context, not a verdict on any single reading. UKHSA's dose comparisons put average exposure in the UK at about 2.6 mSv per year, of which radon accounts for 1.3 mSv on average, and give 0.08 mSv for a transatlantic flight. Effective dose, the EPA adds, is a calculated estimate that does not predict an effect on a person. Objects the EPA lists that can make a Geiger counter react:

  • Uranium glass (glows green under UV light) and some uranium-glazed pottery made before 1973: keep them intact, with no food or drink in them.
  • Luminous radium dials on old watches and clocks: never take one apart.
  • Granite worktops: traces of natural elements give off a little beta and gamma, falling off quickly with distance.
  • Wash your hands after handling; if a piece breaks, ask your local authority how to dispose of it.

Owning, carrying and ordering one in the UK

Owning a consumer Geiger counter that contains no radioactive source needs no licence or permit in the United Kingdom. The battery is about 6.7 Wh (3.7 V x 1.8 Ah), well under the 100 Wh limit that US FAA PackSafe guidance sets for lithium-ion batteries in personal devices, but check your airline's rules before you fly. It works from -10 to 45 °C, measures 127 x 65 x 27 mm, weighs 160 g, has no published water resistance rating and is not a toy. Charge it with a 5 V USB cable, and do not heat it, pierce it or leave it charging unattended.

Geiger Counter Shop sells one pocket Geiger counter, the yellow one described here. The box holds the counter with its built-in battery, a USB-C cable, the user manual, and the manufacturer's inspection slip and warranty card; there is no charger, case, lanyard or radioactive test source. Delivery is free from a UK warehouse for UK orders, with no customs step: prepared in 1 to 2 working days, then delivered in 2 to 5 working days (indicative, not guaranteed). You have 30 days after delivery to change your mind, on top of your statutory rights.

Frequently asked questions

Can I download the readings to a computer?

The manufacturer describes a USB-C connection to a PC to download the data with its own dose management software. That software is not supplied with the counter. There is no Bluetooth and no phone app; dose rates, CPM, cumulative dose and the trend graph stay on the screen.

Why do some guides quote mrem instead of µSv?

American sources often use the rem. The EPA gives the conversions: 1 sievert equals 100 rem, 1 mSv equals 100 mrem and 1 µSv equals 0.1 mrem. So a cumulative dose of 10 µSv on the screen corresponds to 1 mrem. The counter's figures are indicative, not a regulatory dose record.

Can I leave it running all the time?

Yes, with the long-life mode and the alarms set. The manufacturer states 30 days or more in long-life mode, while an independent test found about 5 days in normal use; recharge over USB-C. The cumulative dose, graphs, alarm history and thresholds stay in memory if the battery runs flat.

Why does the reading go up in the mountains or on a plane?

Cosmic radiation increases the higher you are in the atmosphere. The EPA notes that it accounts for about 5 per cent of the average annual dose in the United States, and UKHSA gives 0.08 mSv for a transatlantic flight. Check your airline's battery rules before flying with the counter.

Sources

Our guides are based on the supplier's listings and public documentation. We have not tested the counter ourselves.