FCC vs ICNIRP exposure limits, side by side with the arithmetic
For a phone held against your head, the FCC's limit is 1.6 W/kg averaged over any 1 gram of tissue, while the 2020 ICNIRP guidelines allow 2 W/kg averaged over 10 grams. Canada's Safety Code 6 uses the FCC's numbers. For antennas farther away, the FCC and ICNIRP land within 5 percent of each other from 1.9 to 28 GHz, but at 700 MHz the FCC's power density limit is a third higher than ICNIRP's and about twice Canada's.
None of these comparisons is clean, because the documents average over different amounts of tissue and different stretches of time. Those details change the answer, so we go through them one at a time.
Two kinds of limit
All three rulebooks work in two layers. The first is a limit inside the body. Below 6 GHz that is SAR, the specific absorption rate in watts per kilogram, which is what a phone is tested for. ICNIRP calls this a basic restriction. The second layer is a limit on the field in the air, which is easier to measure near a tower or a rooftop antenna. The FCC calls these Maximum Permissible Exposure (MPE) limits. ICNIRP calls them reference levels. Both are worked out from the inside-the-body limits; the FCC says its MPE values up to 6 GHz are derived from the whole-body SAR limit.
The US rules sit in 47 CFR 1.1310. SAR applies from 100 kHz to 6 GHz. Above 6 GHz the FCC uses only its Table 1 MPE limits, and that table stops at 100 GHz. The ICNIRP 2020 guidelines, published in Health Physics in May 2020 after appearing online in March, cover 100 kHz to 300 GHz and replace the radio-frequency part of ICNIRP's 1998 document. Health Canada's Safety Code 6 (2015) covers 3 kHz to 300 GHz.
SAR limits for the general public
| Limit | FCC, 47 CFR 1.1310 | ICNIRP 2020 | Health Canada Safety Code 6 |
|---|---|---|---|
| Whole-body average | 0.08 W/kg | 0.08 W/kg, averaged over 30 min | 0.08 W/kg |
| Head and trunk | 1.6 W/kg over any 1 g cube | 2 W/kg over a 10 g cubic mass | 1.6 W/kg over any 1 g |
| Limbs | 4 W/kg over 10 g (hands, wrists, feet, ankles, outer ears) | 4 W/kg over 10 g | 4 W/kg over 10 g |
| Averaging time | Up to 30 min | 30 min whole body, 6 min local | 6 min reference period |
| Frequency range for SAR | 100 kHz to 6 GHz | 100 kHz to 6 GHz | 100 kHz to 6 GHz |
All three share the whole-body figure of 0.08 W/kg. ICNIRP explains where it comes from: about 4 W/kg averaged over the whole body for 30 minutes is treated as the level that can raise core temperature by 1°C, workers get a reduction factor of 10, and the public gets a factor of 50. Four divided by 50 is 0.08.
One FCC detail matters for phones: the outer ear counts as an extremity. When a phone is pressed to your ear, the ear itself is judged against 4 W/kg over 10 grams, and the rest of the head against 1.6 W/kg over 1 gram. The FCC reaffirmed that treatment in its 2019 order when it denied a petition asking it to change course.
Why 1 gram versus 10 grams matters
It is tempting to read 1.6 against 2 and conclude the FCC is 20 percent stricter. According to the FCC, the averaging mass pulls in the same direction and widens the gap. Absorption from a phone is not even; it is highest in a small area. A 10 g cube folds in more tissue away from that hot spot than a 1 g cube does, so the same peak produces a lower average. The FCC made this point in its 2013 inquiry, FCC 13-39: for the same averaged value, the peak inside a 10 g cube "could be more than" the peak inside a 1 g cube.
That is why the FCC describes its phone limit as more restrictive than ICNIRP's and IEEE's. The documents don't give a single conversion factor between the two, and we won't invent one. How much the averaging changes things depends on the phone and where its antenna sits.
Time matters as well. A 6-minute average gives a short burst fewer quiet minutes to be averaged against than a 30-minute one. So with identical SAR numbers, Canada's rule is, by that logic, the tighter of the two North American rules.
Power density at four real frequencies
Away from the body, the limits are written as formulas in frequency. Here they are for the general public, as printed:
- FCC Table 1: f/1500 mW/cm² from 300 to 1,500 MHz, and 1.0 mW/cm² from 1,500 to 100,000 MHz, averaged over up to 30 minutes. One mW/cm² equals 10 W/m².
- ICNIRP Table 5 (whole body, 30 minutes): f/200 W/m² from 400 to 2,000 MHz, and 10 W/m² from 2 to 300 GHz.
- ICNIRP Table 6 (local exposure, 6 minutes): 0.058 × f^0.86 W/m² from 400 to 2,000 MHz, 40 W/m² from 2 to 6 GHz, and 55/f^0.177 W/m² above 6 GHz, with f in GHz in that last formula.
- Safety Code 6 Table 5: 0.02619 × f^0.6834 W/m² from 300 to 6,000 MHz and 10 W/m² from 6 to 150 GHz. The reference period is 6 minutes up to 15 GHz. Above that it is 616,000/f^1.2 minutes.
We picked four points across the mobile range: 700 MHz, 1900 MHz, 3.7 GHz and 28 GHz.
ICNIRP rows use its whole-body reference levels (30-minute average). FCC rows are 30-minute values. Canada rows are 6-minute values, and about 2.8 minutes at 28 GHz.
| Rulebook and frequency | Limit |
|---|---|
| FCC, 700 MHz | 4.67 W/m² |
| ICNIRP, 700 MHz | 3.5 W/m² |
| Canada SC6, 700 MHz | 2.30 W/m² |
| FCC, 1900 MHz | 10 W/m² |
| ICNIRP, 1900 MHz | 9.5 W/m² |
| Canada SC6, 1900 MHz | 4.56 W/m² |
| FCC, 3.7 GHz | 10 W/m² |
| ICNIRP, 3.7 GHz | 10 W/m² |
| Canada SC6, 3.7 GHz | 7.19 W/m² |
| FCC, 28 GHz | 10 W/m² |
| ICNIRP, 28 GHz | 10 W/m² |
| Canada SC6, 28 GHz | 10 W/m² |
Source: Our arithmetic from 47 CFR 1.1310 Table 1, ICNIRP 2020 Table 5 and Safety Code 6 (2015) Table 5.
The full set, with ICNIRP's local reference levels added:
| Frequency | FCC (30 min) | ICNIRP whole body (30 min) | ICNIRP local (6 min) | Safety Code 6 |
|---|---|---|---|---|
| 700 MHz | 4.67 W/m² | 3.5 W/m² | 16.2 W/m² | 2.30 W/m² (6 min) |
| 1900 MHz | 10 W/m² | 9.5 W/m² | 38.3 W/m² | 4.56 W/m² (6 min) |
| 3.7 GHz | 10 W/m² | 10 W/m² | 40 W/m² | 7.19 W/m² (6 min) |
| 28 GHz | 10 W/m² | 10 W/m² | 30.5 W/m² | 10 W/m² (about 2.8 min) |
Reading across the rows:
- At 700 MHz the FCC allows 4.67 W/m² against ICNIRP's 3.5, which is 33 percent more. The FCC acknowledged in 2013 that its MPE limits are "slightly less restrictive" than ICNIRP's at some frequencies, and 700 MHz is where that shows among our four examples.
- By our arithmetic, Canada's figure is the lowest of the three at every frequency from 300 MHz up to 6 GHz, where its formula reaches 10 W/m² and meets the others. At 1900 MHz the FCC figure is 2.2 times Canada's, and Canada also averages over 6 minutes, not 30.
ICNIRP's local levels look generous by comparison because they cover a different case, a hot spot on part of the body judged over 6 minutes. They sit alongside the whole-body levels and don't replace them.
Above 6 GHz the rules part ways
Phones that transmit at millimeter-wave frequencies raise a question the FCC's rules still don't answer directly: what limit applies to a small patch of skin next to a 28 GHz antenna? ICNIRP 2020 answers with a basic restriction on absorbed power density, 20 W/m² averaged over 4 cm² of body surface for 6 minutes. Above 30 GHz, the average over any 1 cm² may be no more than twice that, or 40 W/m².
The FCC proposed something similar in its 2019 order, FCC 19-126: a localized limit of 4 mW/cm² averaged over 1 cm² for the public above 6 GHz, running up to 3 THz. That is 40 W/m², the same as ICNIRP's 1 cm² ceiling above 30 GHz. It was only a proposal. The current text of 1.1310, last amended in April 2020, has no localized power density limit and still tops out at 100 GHz, so the plane-wave 1.0 mW/cm² figure governs.
How to read a limit you see quoted
When you see an exposure limit quoted, these questions sort out most of the confusion:
- Which rulebook is it? A SAR value tested under FCC rules (1 g) and one tested under ICNIRP-style rules (10 g) are not the same measurement.
- Is it a basic restriction inside the body or a reference level in the air?
- What averaging time comes with it: 30 minutes, 6 minutes or less?
- What frequency range does the formula cover, and does the rule even reach that band?
- Is it the public limit or the occupational one? Worker limits run about five times higher.
We compare rulebooks here, not products, and none of the documents on this page mentions consumer accessories. If you are reading a product listing at an online EMF sticker shop and have a question about it, ask the EMFCALM team. If your question is which head limit applies to a phone, the US figure is 1.6 W/kg over 1 gram, Safety Code 6 uses the same number, and ICNIRP's is 2 W/kg over 10 grams. Under each of those numbers sits a whole-body ceiling of 0.08 W/kg that all three rulebooks share.