A Pocket Dosimeter That Actually Shipped: The Doze Micro Geiger Counter
I’ve always wanted to measure the background radiation of everyday places. Not for any professional reason — just because I have spent much of my working life around carefully monitored radiation and it seemed strange to know so little about the ordinary kind.
The obstacle was always the instrument. Survey meters are wonderful and they are also the size of a lunchbox. What I wanted was something I could keep in a pocket and forget about until I wanted a number.
About a year ago I found one, backed it, and waited. It arrived. Here’s how that went.
The Kickstarter
The project was called Doze — a tiny dosimeter you carry in your pocket. I found it on Kickstarter, watched the short videos the company had posted of the unit under test, and donated enough to receive a complete unit.
Projected shipment was October of that year. Anyone who has backed hardware on Kickstarter knows how to read a projected ship date, and I noted at the time that you just never know about these things. Especially given the tariff situation.
It slipped, as these things do. But unlike a discouraging number of crowdfunded gadgets, it actually arrived.
And it works.
What it is
The device contains a small Geiger tube designed to detect beta and gamma radiation.
You can set both dose and dose-rate alarms. The feature I’ve found most useful is that it projects the estimated time to reach a dose or dose-rate target at the currently detected rate — which turns an abstract number into something you can reason about.
It also holds a peak capture, so you can walk an area and see the highest rate it caught rather than only whatever it happens to be reading when you look down.
The unit contains a 400 mAh rechargeable battery powered from a USB-C port.
My favorite part might be the click-sound. You can disable it, but it’s classic. It’s not exactly the same as a handheld geiger unit, but it’s close enough.
The units problem
The base units are sieverts.
This is a bummer for Americans conditioned to working in millirem, and it was my first complaint even before I backed it.
The conversion is simple enough to keep in your head:
1 millirem = 10 microsieverts
The good news is the unit is customizable. You should be able to modify the firmware to change the units, among other things. That was my plan going in, and I’ll report back on how it goes.
What it actually reads
Standing in a woodsy area near my house, the instantaneous dose rate was 0.07 microsieverts per hour — about 7 microrem per hour. The peak recorded rate over that same walk was 0.529 µSv/h.
That spread is the interesting part. Background is not a single number. It moves with geology, altitude, building materials, and weather, and an instrument that only shows you the current reading hides that from you.
Oh, it’s also fun to test different types of food you buy from the store.
Putting the numbers in context
Small dose figures are meaningless without a reference frame. The NRC’s website has a good one. A person receives a dose equivalent of about 1 mrem from any one of the following:
- 3 days of living in Atlanta
- 2 days of living in Denver
- 1 year of watching television (on average)
- 1 year of wearing a watch with a luminous dial
- 1 coast-to-coast airline flight
- 1 year living next door to a normally operating nuclear power plant
That last one is the one worth sharing with people who ask what you do for a living.
For a more entertaining and far more visual treatment, read the classic XKCD radiation chart, published about a week after Fukushima. It remains one of the best pieces of science communication on the subject.
It puts a dental x-ray, a transatlantic flight, and standing next to the Chernobyl reactor core on a single page and lets the scale do the arguing.
Where to get one
You no longer need to wait for a crowdfunding campaign. The company, Wekos, now sells the Doze Micro Geiger Counter online to the general public:
Doze Micro Geiger Counter — Wekos Mechatronics
*UPDATE* After this article published, I wrote to Wekos and asked whether they’d extend a discount to readers here. They set up a code for me:
NUCLEAREE — 10% off your entire cart. Good into 2029.
It applies to their whole catalog, not just the dosimeter. I confirmed it works on anything in the store, up to and including their CNC machines (should you want to order one). Enter it as shown; the checkout field capitalizes what you type, so lowercase is fine.
I backed this unit on Kickstarter with my own money and paid full price. Wekos didn’t ask for this article, didn’t see it before it went live, and doesn’t pay me anything when you use the code — they have no affiliate program. The code exists because I asked for one after the fact.
Is it worth it?
If you want a calibrated instrument of record, this is not that, and you should not use it as one. A nuclear plant’s dosimetry program exists for a reason.
Sure, you could also buy a Geiger counter from Amazon (paid link), and at a cheaper price. I’ve been looking periodically for years, but I never found one that fit my desired specs. Doze does.
As a way to satisfy curiosity about the world you walk around in — and as a conversation piece that quietly does more to explain radiation to a skeptical relative than any amount of talking — it has earned its place in my pocket.
Although, I admit, it would be interesting to compare the Doze’s readings to plant dosimetry (or any calibrated unit).
There are sources available (paid link). If I acquire one, I’ll update this article with my report.