EMF Radiation Calculator

At 3 feet (1 meter), a typical WiFi router produces about 0.16% of the FCC safety limit. At 6 feet, it drops to about 0.04%. Because different countries and precautionary groups use different evidence thresholds, RADIHALT treats distance as a practical reduction step rather than a one-size-fits-all safety promise: keeping routers at least 3-6 feet from where you sit or sleep reduces exposure by 75-94% compared to 1 foot away.

A cell phone's EMF output varies dramatically with signal strength. During an active call with poor signal, a phone may transmit at its maximum of 200 mW (LTE/4G). With a strong signal (3-4 bars), it typically drops to 10-30 mW — about 85% less. At 1 foot away, even maximum power is roughly 1.8% of the FCC limit. Phones pressed against your ear are regulated separately by SAR (Specific Absorption Rate) limits.

Bluetooth headphones (Class 2) transmit at just 2.5 mW - 80 times less power than a WiFi router and 80 times less than a phone during a call. At 6 inches from your head, Bluetooth produces about 0.08% of the FCC safety limit. Readers using a precautionary lens may still choose wired options or more distance because mainstream and precautionary sources do not always weigh long-term exposure questions the same way.

The FCC sets Maximum Permissible Exposure (MPE) limits based on frequency. For common wireless frequencies (1.5-100 GHz, covering WiFi, Bluetooth, and most cellular), the general public limit is 1.0 mW/cm². For lower cellular frequencies (300-1500 MHz), it's calculated as frequency/1500 mW/cm². These limits include a 50x safety margin below levels where any biological effects have been observed in research. The limits are defined in 47 CFR 1.1310 and detailed in FCC OET Bulletin 65.

EMF radiation follows the inverse square law: power density decreases proportionally to the square of distance. This means doubling your distance reduces exposure by 75%, tripling it reduces exposure by 89%, and at 10x the distance, exposure is just 1% of what it was. This is why even small increases in distance from EMF sources can make a significant difference — moving a router from 1 foot to 3 feet away cuts exposure by about 89%.

Smart meters transmit at higher power (about 1 W) than most home devices, but they only transmit for brief bursts - typically less than 1% of the time. During those bursts, at 3 feet away, a smart meter produces about 4% of the FCC limit. Time-averaged, the effective exposure is less than 0.04% of the limit, while a precautionary reader may still prefer more distance, better placement, or directional shielding when a meter is close to a bedroom or desk.

This calculator uses the far-field power density formula from FCC OET Bulletin 65: S = PG/(4πr²), where S is power density, P is transmitter power in watts, G is antenna gain (linear), and r is distance in meters. Device specifications come from FCC filings, 3GPP standards, Bluetooth SIG specifications, and FDA regulations. Results are compared against FCC Maximum Permissible Exposure limits defined in 47 CFR 1.1310.

At equal distances, a 5 GHz WiFi router typically produces the highest exposure among home devices due to its combination of 200 mW transmit power and antenna gain. However, the device that causes the most personal exposure is usually your cell phone — not because it's more powerful, but because you hold it much closer to your body. A phone at 6 inches exposes you to more EMF than a router at 6 feet, even though the router transmits at similar power.