Every radiation detector gets a score from 0 to 100% built from six factors, which maps onto the 5-point rating shown on the site (a 0% score would be 1.5 stars; a perfect score, 5). Each factor is scored against fixed reference points, not against the other products in the list, so adding a new model never moves another model’s rating. Detectors are grouped by detector type (sidewall GM tube, mica window GM tube, and scintillation or solid-state) and use the same scale in every group.
| Factor | Measures | Weight |
|---|---|---|
| Sensitivity | published counts per minute for each µSv/h of dose rate | 25% |
| Radiation types | gamma and X-rays, plus beta and alpha | 20% |
| Dose-rate range | highest dose rate it can read | 15% |
| Features | data logging, phone or cloud connection, gamma spectrum | 15% |
| Price | checked price | 15% |
| Warranty | warranty length | 10% |
Where the numbers come from
Detector, radiation types, sensitivity, dose-rate range, energy range, features, battery and warranty come from the maker’s manual, datasheet or product page, or the maker’s own copy on a retail listing. Where a maker gives two figures that conflict, such as two different tops of the dose-rate range, the figure is left out rather than guessed. Prices are checked at Amazon and the maker’s own store, and the lowest price at a store the page links to is used.
The factors
Sensitivity is the published count rate for each µSv/h of dose rate, in counts per minute (CPM), on a log scale, so doubling it always counts the same. 50 CPM per µSv/h scores zero and 5,000 full marks. Makers publish it in different units, so it is converted: 1 mR/h equals 10 µSv/h, so CPM per mR/h is divided by 10, and counts per second are multiplied by 60. Makers also calibrate against different isotopes, usually Cs-137 or Co-60, and the product page shows which where it is published. A detector that counts faster settles on a reading sooner and finds weaker sources, and this is the factor that separates detectors most, so a detector whose maker doesn’t publish it scores zero here and is marked estimated.
Radiation types starts from gamma, which every detector here reads. Detecting beta adds 40% and detecting alpha adds 60%, so a detector listed for alpha, beta and gamma gets full marks and a gamma-only detector scores zero. A type counts only when the maker lists it.
Dose-rate range is the highest dose rate the detector can read, on a log scale: 100 µSv/h scores zero and 100,000 µSv/h full marks.
Features is 35% for data logging (readings stored for download or kept in an app), 35% for a phone or online connection over Bluetooth or Wi-Fi (half that when it is a paid add-on) and 30% for recording a gamma energy spectrum.
Price is the current checked price on a log scale: $1,000 scores zero and $60 full marks.
Warranty is the maker’s warranty: none scores zero and 3 years full marks.
What isn’t scored
The tube or crystal model, energy range, energy resolution, battery type and life, weight, ingress rating and release date are listed but not scored.
Missing data
If a figure isn’t published, that factor gets the neutral middle score (50) and the product page marks it as estimated. Features score neutral only when none of them is published; a feature the maker doesn’t mention otherwise counts as absent. There are two exceptions. Sensitivity, the factor that most separates detectors, scores zero when it isn’t published, so a thin listing can’t rank above a documented one. Warranty also scores zero when no warranty is published. Both are marked estimated.
Ties and discontinued models
Products are ranked by score within each group. Discontinued models stay listed but rank below every current model and can be hidden with the “Hide discontinued” filter.