If you’ve just picked up an EMF meter and aren’t sure what you’re looking at, this article is for you. Getting a reading is easy. Understanding what it’s telling you takes a little more context, and that’s exactly what this covers.

What Your Meter Is Actually Measuring

Before you interpret any number, it helps to know which field type you’re looking at. Most full-spectrum meters measure three different things and display them in three different modes.

Magnetic fields show up in milligauss (mG) or microtesla (µT). These come from appliances, wiring, and anything running on AC power. Electric fields show up in volts per meter (V/m). These radiate from cords and wiring even when devices aren’t actively running.

RF shows up in milliwatts per square meter (mW/m²) or microwatts per square meter (µW/m²). This covers wireless signals from routers, phones, smart meters, and cell towers.

If you need a full breakdown of what each unit means and how to convert between them, the EMF units guide covers all of that in plain language.

The Two Numbers You’ll See: Live and Peak

Most meters show two numbers at once and this confuses a lot of first-time users.

The live number is what the meter is detecting right now at this exact moment. The peak number is the highest reading the meter has captured during the current session. Note that meters handle peak reset differently. The Trifield TF2 resets its peak automatically after a short period. The GQ EMF-390 holds the peak until you manually reset it or the meter powers down. Check your specific meter’s behavior before relying on the peak number. If you haven’t settled on a meter yet, see our recommendations before you go further.

For magnetic fields the live number is usually sufficient. Magnetic fields from appliances and wiring are relatively stable and don’t fluctuate dramatically from moment to moment.

For RF the peak number is the one that matters most. Wireless devices don’t transmit continuously. They pulse, which means the live reading can catch the meter between pulses and show something much lower than what the source is actually putting out. Always note the peak when you’re measuring RF from a router, phone, or any wireless device.

Wait for the Reading to Settle

This is the most common mistake beginners make. When you first point the meter at a source, the numbers will jump around for a few seconds. Don’t read the first number you see.

Hold the meter steady, point it at the source, and wait three to five seconds for the reading to stabilize before you record anything. Moving the meter too quickly can also cause the numbers to spike momentarily from the motion itself rather than from the source you’re measuring.

For RF especially, let the meter run for at least ten seconds near a source before deciding on your reading. The pulsing nature of wireless signals means you need enough time to see the range of variation and let the peak number climb to a representative level.

Rotate to Find the True Peak

If you’re using a single-axis meter, or using the RF mode on any meter including the Trifield TF2, the angle you’re holding the meter at affects the reading you get.

Rotate the meter slowly through different orientations and watch the numbers as you do. The reading will climb in some positions and drop in others. The highest number you find across all orientations is your true peak reading for that source.

I tested this directly at three feet from my router, and you can see how the Trifield TF2 performs across different measurement scenarios in my full review. Pointing the meter directly at the router gave a peak of 9.4 to 9.6 mW/m² on the TF2. Rotating to face left the peak climbed to 16.6 to 19.1 mW/m². If I had stopped at the first reading I would have missed the true peak entirely.

Distance Changes Everything

The single most useful thing your meter can show you isn’t the reading itself. It’s how the reading changes as you move.

EMF fields drop off with distance from the source, and for most sources that drop-off is significant within just a few feet. Measuring at one distance and stopping there gives you an incomplete picture. The more useful habit is to take readings at the source, one foot back, and two feet back, then note where the reading drops to a level you’re comfortable with.

Here’s what that looks like from my own testing using the GQ EMF-390.

At the stove: 67.3 mG practically touching the surface, 5.3 mG at one foot, 2.1 mG at two feet. That’s a 97% reduction over two feet of distance.

At a phone charger: 116 V/m right next to it, 11 V/m at one foot. Moving the charger to the other side of the nightstand is often all it takes to bring a bedroom reading down significantly.

At the router: 150 mW/m² at close range, essentially 0.0 mW/m² outside the room eight feet away. All three of those readings came from my hands-on testing of the GQ EMF-390 in my own home. The RF from a typical router drops to near background levels within one room.

What the Numbers Actually Mean

A reading by itself doesn’t tell you much without a reference point. There are two frameworks worth knowing about and they give very different answers.

Regulatory limits from ICNIRP and the FCC were established around short-term thermal effects, meaning how much energy it takes to heat body tissue. For RF, the ICNIRP limit sits at 10,000,000 µW/m², which is 10,000 mW/m². You will never approach that number with a consumer meter in a typical home. If regulatory compliance is your only concern, most home environments pass easily.

The Building Biology Evaluation Guidelines take a different approach. They were designed specifically for sleeping areas and apply a precautionary framework based on long-term low-level exposure rather than short-term heating effects. Their thresholds are meaningfully lower and are the reference point most EMF-aware individuals use when interpreting home readings.

Here’s a simple reference for sleeping areas using the Building Biology benchmarks.

Magnetic fields

Below 1 mG: low concern 1 to 4 mG: moderate, worth investigating sources Above 4 mG: elevated, take action to identify and reduce

Electric fields

Below 10 V/m: low concern 10 to 50 V/m: moderate Above 50 V/m: elevated, check wiring and cord placement

RF

Below 100 µW/m² (0.1 mW/m²): general precaution level Below 10 µW/m² (0.01 mW/m²): recommended for sensitive individuals

These benchmarks are precautionary, not regulatory. They reflect the judgment of building biology practitioners about what constitutes a reasonable low-exposure environment given the current state of research, not a government-mandated safety limit.

The ICNIRP guidelines haven’t been substantially updated to reflect decades of non-thermal research. The NTP study and the Ramazzini Institute findings both found biological associations at levels well below current regulatory thresholds. That body of evidence is part of why the precautionary benchmarks exist as a separate and more conservative reference point.

Where you land on that spectrum is your call. What the meter gives you is the information to make that decision based on what’s actually in your home rather than guesswork.

Reading Your Bedroom First

If you’re not sure where to start, start in the bedroom. You spend more time there than anywhere else in your home, and more of that time is during sleep when your body is in a restorative state. It’s the highest-value room to measure and the most actionable.

Check your nightstand first. Phone chargers, alarm clocks, and anything plugged in near where you sleep are worth measuring at the distance your body actually sits during sleep. Check the wall behind your headboard if you have outlets there. Then check the room more broadly for RF from any router or device in the adjacent room or hallway.

Measure, note what you find, and then decide if any simple changes make sense. Unplugging a charger, moving a device to the other side of the room, or switching your phone to airplane mode at night are low-effort steps that can make a measurable difference.

A Few Habits That Will Improve Every Reading You Take

Reset the peak reading before each new source so you’re not carrying over numbers from a previous measurement. Let the reading settle before you record it. Take at least three readings at each position and note the range rather than a single number. For RF, always record the peak not just the live reading. Move through orientations slowly rather than sweeping quickly.

None of this requires expertise. It just requires a little patience, and after a few sessions it becomes automatic.

What to Do When a Reading Is High

A high reading is information, not a verdict. The first question to ask is whether the source is something you spend significant time near. A high reading at the back of your stove matters less than a high reading at your pillow.

The second question is whether distance can solve it. For most home sources it can. Moving a device, rerouting a cord, or changing where you sit or sleep relative to a source is often enough to bring a reading down to a level you’re comfortable with.

For help choosing the right tool for what you’re trying to measure, how to pick the right EMF meter for your situation covers the key specs to compare before you spend any money.

I’m not a doctor. Nothing here is medical advice. If you have specific health concerns, talk to a qualified professional.

If you’ve looked at an EMF meter and seen a screen full of abbreviations, you’re not alone. The units EMF meters display aren’t complicated once you understand what each one is measuring, but they’re rarely explained in plain language. The NIEHS groups EMF into two categories by frequency: non-ionizing and ionizing. Understanding that split is the fastest way to make sense of what your meter is showing you. This article does exactly that. If you haven’t picked a meter yet, browse EMF meters for every budget before you dive in.

Why There Are Multiple Units

EMF is not one thing. The term covers three distinct types of fields, and each one is measured differently because each one behaves differently.

Magnetic fields, electric fields, and radiofrequency radiation are related but not the same. A meter that measures one isn’t necessarily measuring the others.

Once you understand which unit goes with which field type, the numbers on your meter start making sense immediately.

Magnetic Fields: milligauss (mG) and microtesla (µT)

Magnetic fields are measured in milligauss (mG) in the United States and microtesla (µT) in most of the rest of the world. The two units measure the same thing on different scales. One µT equals 10 mG, so if your meter displays µT and you want mG, multiply by 10.

Magnetic fields come from anything carrying electrical current: appliances, wiring inside your walls, power lines, and electrical panels. The field strength drops off quickly with distance, which is why a reading right next to your stove can be dramatically higher than a reading two feet back.

When I measured next to my stove with the GQ EMF-390, I got 67.3 mG practically touching the surface. Two feet back that was down to 2.1 mG. That’s a 97% drop over about two feet.

The Building Biology Evaluation Guidelines treat readings below 1 mG as a low concern level in sleeping areas, with readings above 4 mG considered elevated. These are precautionary benchmarks, not regulatory limits, but they give you a useful reference point when you’re interpreting what you find.

Electric Fields: volts per meter (V/m)

Electric fields are measured in volts per meter (V/m). Unlike magnetic fields, electric fields don’t require current to be flowing. They exist around any wire or device connected to a power source, even if nothing is actively running.

Unshielded lamp cords, extension cables, and wiring inside walls all produce electric fields whether a device is switched on or not. This is why the outlet above a headboard can produce a meaningful electric field reading even at midnight with nothing plugged into it.

Your body also conducts electricity, which means readings can vary slightly depending on whether you’re holding the meter or it’s sitting on a surface. For most home testing purposes that variation is minor but worth knowing.

A phone charger sitting on a nightstand is a good example of why electric fields are worth paying attention to. Right next to the charger I measured 116 V/m. About a foot away that dropped to 11 V/m. The charger doesn’t have to be actively charging anything to produce that field.

The Building Biology Guidelines suggest below 10 V/m as a low concern level in sleeping areas, with readings above 50 V/m considered elevated. Moving a device or rerouting a cord is often all it takes to bring a reading down significantly.

RF: µW/m², mW/m², and V/m

Radiofrequency radiation is where the unit situation gets a little more involved, because different meters display RF in different units and they’re all measuring the same thing on different scales.

The most common units you’ll see are microwatts per square meter (µW/m²), milliwatts per square meter (mW/m²), and volts per meter (V/m) used as an RF field strength measurement. Converting between them is straightforward. One mW/m² equals 1,000 µW/m², so if your meter reads 2.5 mW/m² and you want µW/m², multiply by 1,000 to get 2,500 µW/m².

RF comes from WiFi routers, cell phones, smart meters, Bluetooth devices, baby monitors, and cell towers. Unlike magnetic fields, RF doesn’t drop off in a simple predictable pattern. It reflects off walls, passes through some materials more easily than others, and varies constantly depending on what devices on your network are doing.

A reading at one moment near your router can look very different from a reading taken a minute later at the same spot. When I tested my router at close range I measured 68 mW/m², then took another reading less than a minute later from the same position and got 150 mW/m². Same router, same spot, very different numbers.

The Building Biology Guidelines suggest below 100 µW/m² as a general precaution threshold for sleeping areas, and below 10 µW/m² for people who are more sensitive. For context, current ICNIRP regulatory limits sit far above those levels, but those limits were established around short-term thermal effects and haven’t been substantially updated to reflect the body of research on long-term low-level exposure.

The NTP study and the Ramazzini Institute findings both found biological associations at levels well below current regulatory thresholds, which is part of why the precautionary benchmarks exist as a separate reference point.

Peak vs. Average Readings

Most meters give you both a live reading and a peak reading. The live number is what the meter is detecting right now. The peak number is the highest reading captured since you last reset it.

For RF in particular, the peak reading is the more useful number. RF from a router or phone isn’t constant. It spikes when data is being transmitted and drops when the device is idle.

A live reading might catch the meter between pulses and show something deceptively low. The peak reading tells you what the actual high point was.

When I’m testing RF sources I always note the peak, not just whatever the live display shows at the moment I happen to look at it. That habit alone will give you a much more accurate picture of what a source is actually putting out.

A Note on Units Across Different Meters

Not all meters use the same units for the same field type, which can cause confusion when you’re comparing readings between devices.

The Trifield TF2 displays RF in mW/m². The GQ EMF-390 RF screen shows readings in mW/m² as well, but also displays a narrow band reading tied to a specific frequency alongside the broadband figure. Some meters display magnetic fields in µT instead of mG. Some RF meters display in V/m rather than mW/m².

The readings are measuring the same things. The units are just different languages for the same information. Keep the conversion factors handy until they become second nature: 1 µT equals 10 mG, and 1 mW/m² equals 1,000 µW/m².

Putting the Units Together

Most full-spectrum meters display all three field types and switch between them as you change modes. Once you know which unit belongs to which field type, reading the display becomes intuitive.

mG or µT tells you about magnetic fields from wiring and appliances. V/m in electric field mode tells you about fields from cords and wiring. µW/m² or mW/m² tells you about wireless radiation from routers, phones, and other RF sources.

The units are just the language the meter uses to describe what it found. Understanding them takes about five minutes, and after that the numbers stop feeling abstract and start telling you something useful about the spaces you spend time in.

For a closer look at what real-world readings look like across common household sources, my full breakdown of the Trifield TF2 includes measurements from my own home with actual numbers

I’m not a doctor. Nothing here is medical advice. If you have specific health concerns, talk to a qualified professional.