Rad 100 Geiger Counter


(5 reviews) Write a Review
2.00 LBS
Adding to cart… The item has been added

Update as of Feb. 6:  This very popular model of Geiger counter, the Rad 100, is now back in stock, for immediate shipment.


The recent stepchild to the Radalert 100X, and as in its parent model, the Rad 100 is designed for general purpose monitoring of radioactivity.

The Rad 100 is identical to the Radalert in most every respect.  The main difference is that the Rad 100 has no user adjustable audible Alert feature, making possible substantial savings to the consumer.

Like the Radalert 100, the Rad 100 otherwise offers these main features:  

  • Detects Alpha, Beta, Gamma and X-radiation
  • Digital readout on large, easy to read LCD display
  • Readings in CPM and mR/hr, or µSv/hr
  • Total mode for timed counts
  • Audible clicking with each radiation count detected (can turn off)
  • Data Port for connection to computer or data logger

The Rad 100 is an excellent value for the money, offering good sensitivity in a user friendly Geiger counter with digital readout.

This item typically ships within 1 business day.

Specifications for the Rad 100:  


Halogen-quenched, long thin cylindrical Geiger-Mueller tube (LND712)  with side wall of .012" #446 stainless steel, and with thin mica end window

Window Size

1.5 to 2.0 mg/cm² thick;

Radiation Detected Alpha, Beta, Gamma, X-ray
Sensitivity Detects alpha down to 2.5 MeV; efficiency at 3.6 MeV > 80%
  Detects beta at 50 keV w/35% efficiency, at 150 keV w/75%
  Detects gamma and X rays down to 10 keV thru window, 40 keV minimum through case; gamma sensitivity is 1,000 CPM/mR/hr     referenced to Cs-137
  Normal background is approximately 10 to 20 CPM


± 10%typical; ±15% max.

Operating Ranges

.001 to 110 mR/hr; .01 to 1,100 µSv/hr; 0 to 350,000 CPM; 0 to 3,500  CPS; Total from 1 to 9,999,000 counts; Timer: up to 40 hours

Anti-Saturation "Jam" protection allows readout out to hold at full scale in high radiation fields
Indicators LED display, red LED count light, audible beeper for count rate, and audible alert
Display 4-digit liquid crystal display with mode indicators; updates every 3     seconds
Count Light Red LED flashes with each count
Beeper Chirps for each count (can be muted)


At factory to NBS standard Cesium 137 gamma source

Temperature Range -10 deg. to +50 deg. C, 14 deg. to 122 deg. F

Power Required

One 9-volt alkaline battery (included in price of the unit)

Battery Life

2,160625 hours at 1 mR/hr with beeper off


225 grams (8 oz.) including battery


150 x 80 x 30 mm (5.9 x 3.2 x 1.2 in.)

Output Port Stereo 3.5 mm jack on side sends counts to computers, data loggers, other CMOS-compatible devices, and headphones
Input Port Mono 2.5 mm jack provides electronic calibration input
Options Computer cable and software (See Software)
Warranty Two year limited on instrument, 1 year on Geiger-Mueller tube; includes CE mark

Country of Make



5 Reviews Hide Reviews Show Reviews

  • 5
    Great. Very handy. Easy to use and transport.

    Posted by Mike on Aug 25th 2022

    Very handy and easy to transport. Useful for many situations and settings.

  • 5
    RAD 100 purchase

    Posted by Unknown on Feb 3rd 2021

    Item as advertised. Functions properly. Easy to use. Instructions easy to read and understand. If the case had a flat bottom instead of a curved one would be a plus.

  • 5
    a real need for your protection in the coming threat of nuclear war

    Posted by Stan Deyo on Feb 1st 2021

    We are advising all of our listeners (on my Tuesday Hagmann Report appearances) and periodically on our daily news analyses website (standeyo.com) to get the RAD100 digital radiation detector. It is a hand-held, lightweight device with audio feedback of the radiation detected. According to our information from our dealings with some military departments, the US is facing a clear and present danger of both an EMP attack from China and Russia and a brief nuclear attack on the US...

  • 5
    Easy to use and helpful manual

    Posted by Joe on Jun 26th 2017

    This geiger counter is very simpe to use and you can switch the units between Roentgens, Seiverts, and counts per minute. The manual that came with is is very useful and outlines best practices, along with good descriptions of how to use all the features.

  • 5
    decent device

    Posted by Unknown on Feb 7th 2017

    So far so good... is reliable and is simple and easy to use. Recommended