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What is radiation?

Radiation is the emission of energy from any source. When talking about radiation and cancer, we are talking about x-rays, natural background radiation from the earth and sky and the radiation made by nuclear reactors (Gamma rays).

What is a Geiger counter?

The Geiger-Müller is a type of particle detector that measures ionizing radiation. It detects the emission of nuclear radiation: alpha particles, beta particles or gamma rays by the ionization produced in a low-pressure gas in a Geiger-Müller tube, which gives its name to the instrument.

Invented in 1908, Geiger counters remain popular instruments used for measurements in dosimetry, health physics, experimental physics, the nuclear industry, geological exploration and many other fields, and is probably the best-known nuclear instrument to society due to its wide and highly visible use as a hand held radiation survey instrument.

Is Pocket Geiger Counter a real Geiger counter?

Pocket Geiger Counter is not a traditional Geiger Müller counter, which has a pressurized gas tube. It is a silicon semiconductor detector. It consists of a silicon crystal which is doped with impurities to make p- and n-type silicon. A p-n junction, a small region called the depletion zone, is created between p- and n-type silicon because of initial diffusion of electrons and holes. When the detector is irradiated electron-hole pairs are produced within the depletion zone and gives rise to a radiation-induced current.

What are the uses for a Geiger counter?

Hobbyists and individuals use our detectors to test rock samples, to check ambient radiation levels, for gross detection of radon in the home, to learn about radiation and for personal monitoring of cumulative radiation doses. And just for fun!

Can Pocket Geiger Counter detect alpha, beta and gamma radiation?

Due to the shielding, Pocket Geiger Counter can detect X or Gamma Ray radiation only.

Can Pocket Geiger Counter detect Radon gas in the house?

The Pocket Geiger Counter detector can be used to indirectly detect radon gas (it's an alpha emitter). One would do so by concentrating the radon for a few days (1-3) using activated charcoal and measuring the charcoal for any radiation readings. Note this only measures the presence of radon, for accurate pCi/L measurements one can purchase a radon gas detector.

Can Pocket Geiger Counter detect radiation in food or water?

The Pocket Geiger Counter detector is a general purpose survey meter, the typical use for the device is to measure ambient radiation levels, monitor personal dose rates, and determine sources of radiation leakages or identifying rock and metallic samples as radioactive. The detector is not able to detect low radioactivity in food or water unless they are really contaminated by the radiation.

Again, the most comprehensive radiation detection and measurements on food and water are done by labs and government institutions using scintillation detectors and complex methods to concentrate the radioisotopes and to shield the testing from background radiation noise. Scintillation detectors costs tens of thousands of dollars, but are orders of magnitude more sensitive than Pocket Geiger counters.

Can Pocket Geiger Counter detect radiation in the soil?

Yes, you can measure radioactive pollution for soils. To do this, keep the sample in an airtight container and put Pocket Geiger Counter on it with its sensor-side facing down. The sensor-side has a ring-shaped circle.

How is Pocket Geiger Counter calibrated?

At the design stage, the Pocket Geiger Counter detector was calibrated and tested using a standard Cs-137 source and certified by Netherlands National weighing station (Dutch Metrology Institute No.3320408). Then sample Pocket Geiger Counter detectors were tested near Fukushima Daiichi nuclear power station. Although an individual detector is not calibrated, it is inspected before shipping to the customer that the variation in performance is within a certain range.

How long does the battery last?

The battery life, with normal usage should last at least 6 months. Once the battery runs down (<8.5 V), you can simply replace the battery yourself.

Can I take a Pocket Geiger Counter on a plane?

Yes, it is safe to carry a Pocket Geiger Counter on an airplane. It will not emit radio interference. Airport x-ray machines will not damage the Pocket Geiger Counter. Furthermore, the Pocket Geiger Counter contains no radioactive material and emits no ionizing radiation. People have taken our detectors on planes to see for themselves that the radiation on a flight in the air is markedly more (3 - 5 times) than background radiation on the ground.

Where is the Pocket Geiger Counter made?

The Pocket Geiger Counter is designed and manufactured in Japan.

How do we assess Pocket Geiger Counter performance?

Performance of the detector is composed of two parts: sensitivity and accuracy.

In the low-dose region (<0.1 uSv/h), it takes approximately 10-15 minutes to get a stabilized reading. If a dose is higher than 0.1 uSv/h, the recommended measuring time is about 5 minutes. Pocket Geiger Counter requires a longer time to get reliable readings compared with Scintillation or Geiger Müller based detectors. For an "accuracy" check, please read user feedback at

I got a reading in my house of .81 cpm, .05 +-0.01 uSv/h with a 1.97 RMS%. What does that translate into the .34 uSv/h that an average individual background radiation dose would be? What does cpm and the RMS% mean?

Radiation sensors detect radiation particles which is random-distributed in an environment. So there is statistical uncertainty (counting errors) to measuring a radiation level. The error will be reduced depending on the measurement time. In the Pocket Geiger Counter App, statistical error range (1 sigma) is always displayed after +- sign to show exact information of the counting errors. In general, the longer the time it takes to measure, the smaller the error will be.

RMS = SQRT( Sigma{ ( audio_input_signal_level[%])^2 } ) [%], for every last 200 msec. We use the % unit because the audio input function returns 0 to 100% values for audio input level. 100% is a maximum level of audio input in the device. Usually, RMS is almost constant regardless of radiation level because the radiation pulse is too narrow so it will be flattened. RMS should be quite low (<0.1%) because the background noise will be eliminated by the internal circuit (comparator). RMS% is a useful indicator for us to diagnose users' problems.

There is a relationship between cpm (counter per minute) and uSv/hr. It was calibrated using a Cs137 source. Detailed information can be found on www.

Apps For Pocket Geiger

Apps For FTLabs Smart Geiger

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