The FCC uses two kinds of limits for radiofrequency (RF) exposure. Devices held close to the body, like phones, are capped by SAR: no more than 1.6 W/kg averaged over any 1 gram of tissue, and 0.08 W/kg averaged over the whole body. Everything farther away, like cell towers, routers and broadcast antennas, is capped by Maximum Permissible Exposure (MPE), a power-density limit that depends on frequency. For most of today’s cellular and WiFi bands, MPE for the general public is 1.0 mW/cm², which works out to 10,000,000 µW/m² in the units most home meters display.
Those numbers live in a single federal regulation, 47 CFR § 1.1310. This page is a lookup reference: what the limits are, where they came from, how compliance gets tested, and how to compare them to a reading on your own meter. Whether the limits are adequate is a separate argument, covered in our piece on whether the FCC’s limits are outdated.
The Two Kinds of Limits
The split between SAR and MPE comes down to distance from the body.
- SAR (specific absorption rate) measures how much RF energy tissue actually absorbs, in watts per kilogram. It applies to portable devices, defined as those used within 20 cm of the body: phones, tablets, smartwatches, earbuds.
- MPE (maximum permissible exposure) measures the field in the space around you: power density in mW/cm², or electric and magnetic field strength in V/m and A/m. It applies to mobile devices used 20 cm or more from the body and to fixed transmitters such as cell sites and broadcast towers.
The reason is practical: close to a phone, the field is too uneven for a power-density number to describe what tissue absorbs, so the lab measures absorption in a model head or body instead.
Above 6 GHz the rules switch over: compliance is assessed with power density even for devices held against the body. That matters for millimeter-wave 5G phones, which are evaluated on power density for their millimeter-wave radios and on SAR for their lower-frequency bands.
SAR Limits: The Full Table
| Exposure category | Whole-body average | Peak, any 1 g of tissue | Extremities (10 g) | Averaging time |
|---|---|---|---|---|
| General population | 0.08 W/kg | 1.6 W/kg | 4 W/kg | up to 30 minutes |
| Occupational | 0.4 W/kg | 8 W/kg | 20 W/kg | up to 6 minutes |
The 1.6 W/kg figure is the one on phone spec sheets, but the extremity row is worth knowing too. Devices worn on the wrist, such as smartwatches and fitness bands, are tested against the 4 W/kg extremity limit averaged over 10 grams, because hands, wrists, feet and ankles are treated differently from the head and trunk.
Where the numbers came from
The FCC adopted these limits in August 1996, drawing on NCRP (1986) and ANSI/IEEE (1992) recommendations. Animal studies had found behavioral disruption starting around a whole-body SAR of 4 W/kg, where absorbed energy heats tissue. Dividing by a safety factor of 10 gives the occupational limit (0.4 W/kg); dividing by 50 gives the public limit (0.08 W/kg). Our SAR ratings explainer walks through that derivation. Every number in the table traces back to preventing tissue heating, which is both the framework’s strength and the center of the dispute over non-thermal effects.
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Search Your AddressMPE Limits by Frequency
MPE limits change with frequency because the body absorbs RF differently at different wavelengths. Here is the general-population table from § 1.1310, with f in MHz:
| Frequency | Electric field | Magnetic field | Power density | Averaging |
|---|---|---|---|---|
| 0.3–1.34 MHz | 614 V/m | 1.63 A/m | (100 mW/cm²)* | 30 min |
| 1.34–30 MHz | 824/f V/m | 2.19/f A/m | (180/f² mW/cm²)* | 30 min |
| 30–300 MHz | 27.5 V/m | 0.073 A/m | 0.2 mW/cm² | 30 min |
| 300–1,500 MHz | — | — | f/1500 mW/cm² | 30 min |
| 1,500–100,000 MHz | — | — | 1.0 mW/cm² | 30 min |
\Plane-wave equivalent power density.*
The occupational table follows the same shape at five times the power density (for example, 5 mW/cm² above 1.5 GHz) with a 6-minute averaging window instead of 30.
Why the limit dips between 30 and 300 MHz
The strictest part of the table covers FM radio and VHF TV, for a physical reason: the adult human body is roughly the right length to absorb energy most efficiently in this range, a bit like an antenna tuned to it, so the same field deposits more heat. Below and above that band, absorption is less efficient and the allowed power density rises.
The same limits in the units your meter shows
Most consumer RF meters display µW/m² or V/m, not mW/cm². Converting the FCC limits for the bands you’re most likely to measure at home (V/m values assume far-field conditions, where power density = E²/377):
| Source | Typical frequency | FCC public limit | In W/m² | In µW/m² | Approx. V/m |
|---|---|---|---|---|---|
| FM radio | 88–108 MHz | 0.2 mW/cm² | 2 | 2,000,000 | 27.5 |
| Cellular low band | 600 MHz | 0.4 mW/cm² | 4 | 4,000,000 | 38.8 |
| Cellular 850 band | 850 MHz | 0.57 mW/cm² | 5.7 | 5,700,000 | 46.2 |
| Mid-band cellular, WiFi 2.4/5/6 GHz, C-band, mmWave | above 1.5 GHz | 1.0 mW/cm² | 10 | 10,000,000 | 61.4 |
Conversion to keep handy: 1 mW/cm² = 10 W/m² = 10,000,000 µW/m². Decimal slips are common in online charts.
As a worked example, a meter reading of 1,000 µW/m² near a WiFi router is one ten-thousandth of the FCC limit for that band. That number tells you nothing about long-term biological effects; it only shows how far below the heating threshold the reading falls. Precautionary guidelines, like the building-biology numbers in our guide to how much EMF is safe, set their targets thousands of times lower, which is why the same reading can look trivial against one standard and elevated against another.
General Population vs. Occupational
The two tiers aren’t about who someone is. They depend on whether the person knows about the exposure and can control it.
- Occupational/controlled limits apply to people exposed as part of their job who have been made fully aware of the exposure and can act on it, through training, monitoring and access control. Tower climbers and broadcast engineers are typical.
- General population/uncontrolled limits apply everywhere else: residents, passersby, and workers who haven’t been trained or can’t control the exposure. All consumer devices are held to the general-population limits.
How Compliance Actually Works
Phones and other portable devices
Before any phone can be sold in the US, it must be certified through FCC equipment authorization, which includes a SAR test report. The test is deliberately worst-case:
- The phone transmits at maximum power on each band.
- Head testing uses the SAM phantom, a liquid-filled model of a large adult head, with the phone held against the cheek and in a tilted position.
- Body-worn testing uses a small air gap, typically 5 to 15 mm. Hotspot mode is tested separately at 10 mm.
- The reported SAR is the highest value found across all those tests.
A reported SAR therefore describes how close a phone can get to the limit, not what you absorb on a typical call, and the FCC itself cautions against ranking phones by it.
Routers and other “mobile” devices
Devices meant to sit away from the body, like WiFi routers and desktop hubs, are usually evaluated with MPE at a separation of 20 cm. That’s the source of the line in many router manuals about keeping at least 20 cm between the antenna and your body.
Cell towers and fixed transmitters
The carrier or broadcaster holding the license is responsible for compliance, under 47 CFR § 1.1307:
- Exemptions by formula. Many installations qualify for an exemption based on transmit power, frequency and how close people can get. A source of 1 mW or less is exempt regardless of distance. Larger sources run a calculation, and elevated antennas often qualify because the nearest spot the public can reach is far from the antenna face.
- Evaluation when not exempt. Otherwise, the licensee must evaluate exposure against the § 1.1310 limits and certify compliance. If a site would exceed the limits, it needs a full environmental assessment.
- Shared responsibility. At a site with several carriers, every licensee whose signal contributes more than 5% of the applicable limit in an over-limit area shares responsibility for fixing it.
- Signs and access control. Areas near antennas that can exceed the limits must be marked and controlled: blue NOTICE signs where the general-population limit is exceeded, yellow CAUTION and orange WARNING signs at higher levels, and red DANGER signs where contact could cause serious injury.
Because the limits apply wherever people can actually be, the areas that can exceed the public limit at a cell site are usually close to the antenna face, on a rooftop or up the tower, rather than on the ground below. Our cell tower distance guide covers the geometry, and the EMF Radar map shows which towers and antennas are registered near your address.
What the FCC Limits Don’t Cover
- Power-line and household electrical fields. The FCC table starts at 300 kHz. There is no federal limit on 60 Hz magnetic fields from power lines, wiring or appliances in homes. A few states, including New York and Florida, set field limits at the edge of transmission-line rights-of-way.
- Non-thermal effects. The limits were built to prevent heating. Whether long-term, lower-level exposure has other biological effects is the central dispute.
- Children specifically. The same limits apply to everyone, and the phone test uses an adult-sized head.
- Your total across devices. Each device is certified on its own. MPE at a fixed site does sum the transmitters located there, but nothing adds up the phone, watch, earbuds and router you’re using at the same moment.
Where the Rules Stand in Late 2026
The values in the tables above are the 1996 numbers. The FCC reviewed them in a 2013 inquiry and, in a late-2019 order, unanimously voted to keep them while revising how compliance is shown, including the exemption formulas above.
In August 2021, the D.C. Circuit ruled in Environmental Health Trust v. FCC that the agency hadn’t adequately explained why the evidence submitted on non-thermal effects didn’t warrant changes, and sent the decision back for a reasoned explanation. The court didn’t find the limits unsafe, and it didn’t order new ones. Our policy review piece covers the gaps critics point to.
On September 17, 2026, the FCC opened a comment period on the issues the court sent back (testing procedures, effects on children and long-term exposure, and environmental impacts), and HHS opened a broader request for information on wireless health research, as we reported in Pulse. The two dockets drew 1,519 submissions in their first two weeks, and both comment periods closed in late October. The FCC has said it will give particular weight to comments reflecting specialized health and safety expertise. Any change to the numbers would require a separate rulemaking, so as of this writing the limits in this article are still the law. For how they compare internationally, including ICNIRP’s 2 W/kg over 10 g, see our country-by-country comparison.
Frequently Asked Questions
What is the FCC SAR limit for cell phones?
The limit is 1.6 watts per kilogram, averaged over any 1 gram of tissue, measured with the phone at maximum power against a model head and body. Every phone sold in the US has to test at or below that value. The whole-body limit is 0.08 W/kg, and wrist-worn devices are held to 4 W/kg over 10 grams.
What is the FCC exposure limit for cell towers?
Towers fall under MPE power-density limits, which vary by frequency. For the general public it’s 1.0 mW/cm² (10 W/m²) for bands above 1.5 GHz, f/1500 mW/cm² between 300 and 1,500 MHz (about 0.57 mW/cm² at 850 MHz), and 0.2 mW/cm² for 30–300 MHz. Exposure is averaged over 30 minutes.
How do I compare my EMF meter reading to the FCC limit?
Convert to the same units. For most cellular and WiFi bands, the public limit is 10,000,000 µW/m², or about 61 V/m. Divide your reading by that figure to see what fraction of the limit it represents. Keep in mind that inexpensive meters can be off by a wide margin, especially for RF.
Have the FCC RF exposure limits changed since 1996?
No. The FCC reaffirmed the 1996 values in 2019 while updating compliance procedures. The September 2026 FCC and HHS comment proceedings could lead to new rules, but only through a separate rulemaking.