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How To Understand The Different Measurement Units That Are Used To Measure EMFs

Posted by Lloyd Burrell on May 23, 2012 under EMF facts | 22 Comments to Read

When I first started researching electromagnetic fields one of the biggest problems I had was getting my head around all the jargon; trying to understand what all the different measurement units that are used to quantify EMFs meant.

Most people have vaguely heard of terms like Volts, Watts, Gauss and Hertz but then between having heard of a term and having even a vague understanding of its meaning, there is often a big gulf. Here I hope to answer at least some of your questions.

EMF Basics

EMFs are mainly characterized in terms of frequency and strength.

Frequency is measured in hertz, which means cycles per second. Your electricity supply for instance, operates in the 50 or 60 Hz frequency range, depending on where you live. FM radio operates in the mega hertz range, so when it says 98.6 on the dial that means 98.6 MHz (or 98,600,000 hertz). Cell phones and similar wireless devices operate mainly in the 1-2 GHz range (1GHz = 1000,000,000 Hz).

The other parameter is signal strength. So at any given frequency, 50Hz or 98.6 MHz or 1.8 GHz (that used by many cell phone operators), you can have different signal strengths. And these different signal strengths are measured in different units, Gauss, Volts, Watts etc. according to the frequency and according to the nature of the signal.

What Are The Most Common Units of Measurement For Measuring RF Radiation?

RF radiation or radio frequency radiation is situated in the GHz frequency range.

The most common units of measurement for measuring radio frequency radiation are microWatts per square meter (µW/m2), microWatts per square centimeter (µW/cm2), milliWatts per square meter (mWm²) and Volts per meter (V/m). And herein lies the problem, there is no accepted standard on this.

Firstly lets get clear on how to convert between microWatts per square meter (µW/m2), microWatts per square centimeter (µW/cm2) and watts per square meter (W/m²).

To convert between units expressed in square meters is quite simple (remember that “mW” means “milliWatts” and “µW” means microWatts):

1 W/m² = 1000 mW/m² = 1000,000 µW/m²

Similarly in square centimeters:

1W/cm² = 1000 mW/cm² = 1000,000 µW/cm²

Where this gets more complicated is converting between units that are expressed in square meters and those that are expressed in square centimeters for instance:

1 μW/cm² = 10,000 μW/m²=10mW/m²

What Are The Best Units of Measurement For Measuring RF Radiation?

That depends on what your objectives are. But for personal EMF measurement we are interested in relatively low levels of radiation because we now know that even relatively weak RF signals have biological consequences. Most RF meters for personal use have now incorporated this parameter. For instance the Cornet meters now use V/m and mW/m² and the Acoustimeter uses V/m  and μW/m². I recommend meters that give readings in V/m this is the most meaningful measurement for personal testing and protection.

What is the Advantage of Obtaining Measurements in V/m?

Technically speaking W/m² (and its derivatives mWm², μW/cm² etc.)  measures something called Power Flux Density. PFD is measured by averaging the power over time (6 minutes for official RF measurements) and is therefore most relevant to measuring the heating effect of RF radiation.

Studies show that it is the pulsing effects of EMFs that are particularly dangerous. V/m is considered the best unit of measurement for measuring microwave signals at non-thermal levels (as used by WiFI and cell phones and the like) because it gives peak signal strength (some devices have peak power levels up to 100 times more than their average power levels).

Conversion Formulas for Radio Frequency (RF) Radiation

The most commonly asked question is how to convert between W/m² and V/m. There is a conversion formula for this but W/m²only converts into V/m for continuous signals (things like VHF and FM radio signals).

Formula for Conversion from W/m² to V/m

V/m = (W/m2 x 377)1/2

Example: to convert 10 W/minto V/m you would make the following calculation, (10W/m2 x 377)1/2 = 61 V/m

Formula for Conversion from V/m to W/m²

W/m² = (V/m)² / 377

Example: to convert 6 V/m into W/m² you would make the following calculation, (6 x6)/377 = 0.1 W/m2

But W/m² is rarely used for personal RF exposure because the levels which impact health are known to be of lesser strength by several magnitudes

Measurement Units for AC Magnetic Fields

The most common units of measurement for AC magnetic fields are Gauss and Tesla.

In Canada and the US the standard measurement unit is Gauss and in most other parts of the world it is Tesla. Both units measure exactly the same thing, the magnetic field generated by current flow. Because we know that even relatively weak magnetic fields have biological consequences  the most common units of measurement are milliGauss (mG) and microTesla (μT), these are the measurement units used by the Cornet ED75 and Trifield 100XE (mG only).

See the formula below for a better understanding of their relationship.

Formula for Conversion between Gauss and Telsa

The conversion is quite simple:

1mG = 0.1 μT

which also means:

1 μT = 10 mG

Measurement Units for AC Electric Fields

AC electric fields are commonly measured in Volts/meter. So this is the same unit of measure as RF radiation, as explained above, the difference is the frequency. With RF radiation we are mainly concerned with radiation in the GHz range whereas AC electric fields are typically in the 50/60 Hz, thats to say the frequencies found in electrical wiring and powerlines. The Trifield 100XE measures AC electric fields in V/m.

I hope this gives you a basic understanding of what the different measurement units that are used to measure EMFs mean.

  • Ruth Ruddock said,

    Thank you Lloyd for explaining this. What I don’t understand is how to tell when a reading is in a dangerous level for a person to be living in…such as my apartment. I know that the meter shows the spiking of the 31 smart meters below me in the parking garage, and they spike every 15 seconds or so…so this must mean that this is not a place anyone should live in, right?
    I am increasingly more sensitive now than I was just months ago. I can not move for another month…my sleep is so disturbed now that I don’t get any quality sleep anymore…and only 5 hours a night. How can I protect myself so that I can sleep better until I do move?
    Thank you,
    Ruth R.

  • Lloyd said,

    Hi Ruth
    The mass of information on this website is all well and good, but if you are getting a reaction to these EMFs then this is what you must listen to. Clearly the smart meters are impacting your health and are dangerous. You don’t need a meter to tell you this, or any regulatory authority – I speak from experience. What can you do? Honestly, you need to move now. You can’t move, move anyway (even when you do move there will still considerable effort required to get your health back to normal).

  • Dubal said,

    Many thanks for the article.
    Can you also please mention the acceptable upper limits of these types of radiation?
    Thanks in advance.

  • Lloyd said,

    My recommendations are to follow the advice of the Bioinitiative report (see that’s to say 1 mG (0.1μT) for ELFs ( low frequency EMFs) and 0.01 μW/cm2 ( 0.19 Volts/meter) for indoor RF exposure.

  • Karla said,

    Hi Ruth
    In the interim to get some temporary relief you can try showers to disperse the emf from your body, and earthing – outside bare feet or buy a small earthing mat. Melatonin helped me get my sleep patterns back in order & has amazing protective heath benefits – check for contraindications with other meds. I found Magnesium helps soothe also. But like Lloyd says you need to move asap, I was in the same position as you and ended up in a few hotels, my inlaws and in my car on a few occassions to escape the exposure until I could move house. Can you find a better room to sleep in temporarily in your present home? A meter will help you find a better home in future. Best wishes, K

  • Ruth Ruddock said,

    Thank you all for your comments. Besides the HF35C meter which I will be receiving soon, and I ordered this one primarily to detect smart meter spiking, was wondering if a small, inexpensive (less than $100) would be to mesasure the EMF in sleeping areas, or any living space.
    The place that I may move to has one meter, is out in the sticks (country) with no close neighbors, and the meter is out a little ways on a pole, not attached to the building, so I see that as a plus. Still I will want to shield from that one meter or shield the meter itself, I would think…right? Mainly, I want to be able to be shielded while I sleep.
    Any comments are appreciated.
    Ruth in sunny Wisconsin, USA

  • Omana Mammen said,

    The article is useful.
    How to calibrate a radiation meter, measuring microwatts/m2 to watts/m2.

  • Pedro Freitas said,

    Usefull explanations. Thanks!!

  • barb said,

    we made many changes in our home when we noticed the SMART water meter in our basement spiking (it has been removed but the reader is still attached to our house): we no longer have metal in our beds: wooden frames only. ALL electrical is removed from rooms such as phones, tvs, computers, lamps not in use are unplugged. we will be getting rid of Wifi- for sure! We do NOT use a microwave. Still, there are many towers nearby…but things have changed for the better because of this info. Thank you SO much! :)

  • Verasak said,

    I sit behind antenna of mobile base station. They said the EMF is low since the radiation will go at the front of antenna.
    I want to hear your comments
    Thank you

  • Lloyd said,

    Most official advice on this subject is about allaying people’s fears. It is possible that you are not being exposed but I would want to get some reliable RF measurements on this. The only way to know for sure if you are being exposed is to test with a meter.

  • Kathleen said,

    I made a partial Faraday cage to shield a friend’s bedroom from 4 smart meters using aluminum window screening. Due to the configuration of the property, I hung two layers of screening behind the meters and one layer beside the meters. I connected the screening behind and beside to each other.
    Then I grounded the mess by taking an old extension cord, cutting off the plugs, and stripping both ends of the cord. I wove the wire at one end into the screen and secured it with electrical tape. I attached the other end of wire to a metal skewer and drove that into the flowerbed outside. When the Baubiologist came to measure with his HF35 C meter, he was quite surprised to learn that my “girlie jury rig” had solved the problem quite nicely.
    The Baubiologist taught me how to use Mylar “emergency blankets” (available at sporting goods stores) in a similar fashion. You just need to realize that only one side of an “emergency blanket” is conductive, so that if you are attaching several together side by side, or on top of each other, you must touch the conductive side of one to the conductive side of the other. Then be sure to attach your ground wire to the conductive sides. If you don’t ground your setup, it will attract a lot of voltage, and you will exchange one problem for another.
    (Test which side of the “emergency blanket” is conductive by setting a multimeter on “Ohms” [the omega symbol]. Touch the metal tip of the black probe to the metal tip of the red probe. If your meter is working correctly, you will get a reading on the readout. It doesn’t matter what the reading is, as long as it is different from the reading before you touched the metal probe tips together.
    Then touch both probes to one side of the “emergency blanket” a couple of inches apart from each other. If the readout shows no change, that is the nonconductive side of the blanket. If the readout shows numbers, [digital] or the needle moves [analog], that is the conductive side. It is a good idea to test each side of the “emergency blanket” just to be sure things are working correctly.)

  • Karen S. said,

    Hi Lloyd,
    A smart meter was installed on my neighbors house (I was able to deny install on my own). The subdivision I live in is about 80% installed with my backyard neighbors still needing to be done. We thought we were adequately prepared because we live in an aluminum-sided 2 story colonial, plus we covered ground-floor windows completely with alum screening. Upper floor windows are covered in Veil-Shield. I even put alum screening around the upper interior foundation of our basement to cover the gap where the alum siding stops (as well as a few windows) and the concrete foundation begins. Everything is grounded.
    Well, within 1 hour of the install on the neighbors house and on our street I could feel the bad effects. I can feel a difference in all levels of our home, from the basement to the second floor, however, the worst is the second floor, and readings decrease as you go down. (variable readings from 0.0175 to 0.0400 V/M on highest floor, to 0.0147 -0.0154 V/m in basement.
    My question for you, is we are considering using Y-shield on the ceiling of rooms on the second floor. But I’m so sensitive to RF (as you can see by those readings) that I’m wondering if the Y-shield will make any impact? We are kind of puzzled as to how it’s getting into the house (esp the upper levels when the meters are about 3 feet off the ground.
    Thanks for any advice you can pass along. I bought your book and have learned a great deal from it and from your website. You are a blessing to all of us EHSs.

  • Lloyd said,

    Hi Karen
    The RF readings you are getting are low by most peoples standards. But that’s irrelevant, given your body’s reaction clearly they need bringing down lower still.
    RF radiation can be compared to natural light. If you have ever tried blackening out a room when its daylight outside its quite difficult, the light gets through the tiniest cracks and lights up your room. The problem with aluminum is all the corners, joins, rivet holes, screw holes etc. Somehow, someway the signal is getting through.
    You need to shield better, the Yshield is a relatively easy way of doing this. Test, note down your readings, paint the ceiling, then test again. Proceed like this with all the surfaces until you get your readings down and start to feel better.
    Another thought, double check that there is no device internally that is creating a signal – go round from room to room with your RF meter at different times of the day.
    Glad you liked my book.

  • Lize Swanepoel said,

    Me and my family are living in Midrand South Africa. A cellphone base station has been erected 37 meters from my house without our permission. Several cellphone towers have now also been erected in the nearby vicinity, “communicating” towards the base station We have started legal proceedings but do not have much hope in a possitive outcome.Is there any scientific evidence that you know of that we can use in the upcoming court case?We unfortunately cannot afford all the recommended protection that are advised.{The neighbours are paying for the court case)

    I already can feel the effect of the radiation on my body in the form of severe muscle pains and blood tests have revealed raised inflammation.

    I would gladly hear from you.

    Kind Regards

    Lize Swanepoel

  • Lloyd said,

    Hi Lize
    Dr Kumar of India had the same problem as you he compiled a 72 page report outlining the dangers of cell towers, see

  • Edward said,

    Hello Lloyd,

    Thanks for your emails.
    Do you know of a supplier of EMF meters in South Africa?

    kind regards


  • Lloyd said,

    Hi Edward
    Radmeters deliver all over the world, see

  • Carolyn said,

    Do you have a SIMPLE chart that shows approximate acceptable numbers for exposure to various equipment like WiFi, cell phones, microwave ovens, smart meters, printers, etc. For one like me who does not understand watts, volts, millivolts, gauss, etc. but who has ordered a Cornet ED78S meter, I want to be able to analyze the results I’m getting (when it arrives). A chart would be SO helpful. Thank you for this excellent web site! I don’t understand some of the technical part but am gradually learning.

  • Lloyd Burrell said,

    Unfortunately no such chart exists because there are no ‘safe’ levels…..studies show biological effects at very low levels. When you receive your Cornet meter I suggest you watch my video closely, it shows how to use your meter in the simplest way possible.

  • Bel said,

    Just wanted to say thanks for the interesting site.
    I’m a trainee train driver (for las 12months) and am concerned about emr – given I sit right in the middle of 1500vDC (overhead) and its earth point (train track). I have experienced major health probs since starting this work and wonder if there is a link. But strangely, everyone at work looks at me blankly when I ask what is known re drivers exposure to emr in the cab.

  • Harrison said,

    Lloyd, Regarding the right meter, I had an electrosmog meter that I had been using to measure RF’s in mV/M, but was told that it wasn’t sensitive enough to measure the new Smart Meters. So I bought the HF Meter because it has a switch which allows a choice of peak or average indication mode, giving me measurement of both digital and analog signals. Two ranges: 1 – 1999 µW/m² (same as 0.1 – 199.9 nW/cm²) and 0.1 – 199.9 µW/m² (same as 0.01 – 19.99 nW/cm²). So, I see that you’re recommending the mV/m that this one doesn’t have, so I’m wondering if I’m ok with this one. thanks,

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