EMF Radiation Calculator
See your real exposure from everyday devices — calculated with physics, not fear. Free tool using published device specs and FCC safety limits.
Distance Calculator
How much EMF at your distance?
Select a device and set your distance. We calculate real power density using the inverse square law and compare it to FCC safety limits.
Well below safety limits
Power Density
1.90 µW/cm²
FCC Limit (2400 MHz)
1.00 mW/cm²
Distance tip: Moving to 6.0 ft would reduce your exposure by 75%. The inverse square law means doubling distance cuts exposure by ~75%.
Device Comparison
How do everyday devices compare?
All personal and home devices shown at the same distance, ranked by exposure as a percentage of FCC safety limits.
Percentages show power density as a fraction of the FCC Maximum Permissible Exposure (MPE) limit at each device's operating frequency. All calculations use far-field inverse square law: S = P·G / (4πr²).
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The Physics
How EMF exposure actually works
The Inverse Square Law
EMF power density drops with the square of distance. Double your distance and exposure falls by 75%. Triple it and you're down to just 11%. This is the same law that governs light, gravity, and sound.
The Formula We Use
From FCC OET Bulletin 65, the standard far-field power density equation:
S = PG / 4πr²
S = power density, P = transmit power, G = antenna gain, r = distance
FCC Safety Limits
The FCC Maximum Permissible Exposure (MPE) limits in 47 CFR 1.1310 include a 50x safety margin below levels where any biological effects have been observed. For WiFi/Bluetooth frequencies (1.5+ GHz), the public limit is 1.0 mW/cm².
The biggest insight most people miss
Your phone pressed against your ear during a call exposes you to far more EMF than a WiFi router across the room — even though the router may transmit at similar or higher power. Distance is the dominant factor, not power.
A WiFi router at 10 feet produces about 0.02% of the FCC limit. Your phone during a call at 6 inches produces about 1.8% of the limit — roughly 90x more exposure. The practical takeaway: use speakerphone or keep your phone a few inches from your ear for the most meaningful exposure reduction in your daily life.
Methodology & Data Sources
How Is This EMF Calculator's Data Calculated?
Full transparency on the math, the data sources, and what this tool can — and cannot — tell you.
The inverse-square law
For an isotropic point source radiating power P into free space, the time-averaged power density S at distance d falls off with the square of distance:
S = P / (4π · d²)
S in W/m², P in watts, d in meters
For directional antennas (most consumer WiFi routers, cell towers) we multiply by linear gain G, giving the FCC OET-65 far-field form S = PG / (4πr²). That's the formula the calculator uses.
Real environments include reflections, multipath fading, absorption by walls and bodies, and near-field effects close to the radiating element. The calculator therefore returns order-of-magnitude estimates suitable for comparison and intuition — not lab-grade measurements.
What Data Sources Power This Calculator?
- •FCC Office of Engineering and Technology (OET) Bulletin 65 — the authoritative methodology for evaluating RF exposure compliance, including the far-field power-density formula. fcc.gov/general/oet-bulletins-line
- •FCC SAR test reports for individual phone models — every device sold in the US files a Specific Absorption Rate report, publicly searchable by FCC ID at fcc.gov/oet/ea/fccid.
- •ICNIRP 2020 Guidelines on limiting exposure to electromagnetic fields (100 kHz – 300 GHz) — the international reference adopted across the EU and much of the world.
- •IEEE C95.1-2019 — Safety levels with respect to human exposure to electric, magnetic, and electromagnetic fields, 0 Hz to 300 GHz.
- •Manufacturer specifications for routers, laptops, baby monitors, and smart meters. Transmit-power claims in the device list are taken from publicly available FCC equipment-authorization filings, not marketing copy.
- •Supporting standards: 47 CFR 1.1310 (US RF exposure limits), 3GPP TS 36.101 (LTE/4G UE power classes), Bluetooth SIG Core Specification 5.4, and FDA 21 CFR 1030.10 (microwave oven leakage).
What Are the Limits of This Estimate?
This is a transparent model, not an enclosure of every real-world effect. Specifically, the calculator:
- •Assumes a point source in free space— close to the antenna (the "near field") the actual field structure is more complex and the formula over- or under-estimates depending on geometry.
- •Does not model body absorption or SAR directly. SAR (W/kg) is measured separately by accredited labs against tissue-simulating phantoms; we cite manufacturer SAR figures rather than computing them.
- •Ignores reflections, multipath, and standing waves from walls, mirrors, and metal surfaces, which can locally raise or lower power density.
- •Uses peak transmit power for most devices. Real exposure is time-averaged — phones with good signal and smart meters with brief duty cycles transmit at far lower effective levels.
- •Does not account for simultaneous multi-source exposure (e.g., a phone, router, and laptop active at once).
- •Is not a medical device and is not a substitute for a calibrated RF meter or a professional site survey if you need certified measurements.
How Does This Compare to Regulatory Limits?
Both the FCC general-public MPE limit (47 CFR 1.1310) and the ICNIRP 2020 general-public limit are 10 W/m² (1.0 mW/cm²) for frequencies above ~2 GHz. Typical computed values from this calculator:
| Scenario | Power density | % of FCC/ICNIRP limit |
|---|---|---|
| WiFi router at 1 m (200 mW) | ~0.016 mW/cm² | ~1.6% |
| WiFi router at 3 m | ~0.0018 mW/cm² | ~0.18% |
| Phone (max 200 mW) at 30 cm | ~0.018 mW/cm² | ~1.8% |
| Bluetooth (2.5 mW) at 15 cm | ~0.0009 mW/cm² | ~0.09% |
| Smart meter at 1 m (peak) | ~0.08 mW/cm² | ~8% (peak burst) |
Values rounded for illustration. The percentages reflect a point-source free-space estimate at the listed peak transmit power; time-averaged exposure is typically lower. Use the calculator above for your own scenario.
Common Questions
What are the most common questions about EMF exposure?
What is a safe distance from a WiFi router?
At 3 feet (1 meter), a typical WiFi router produces about 0.16% of the FCC safety limit — well within safe levels. At 6 feet, it drops to about 0.04%. While there's no single 'safe distance' because all tested distances are far below limits, keeping routers at least 3-6 feet from where you sit or sleep is a reasonable precaution that reduces exposure by 75-94% compared to 1 foot away.
How much radiation does a cell phone emit?
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.
Is Bluetooth radiation harmful?
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. Bluetooth Low Energy (BLE) devices like fitness trackers emit even less at just 1 mW.
What are the FCC EMF safety limits?
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.
How does distance affect EMF exposure?
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%.
Are smart meters dangerous?
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. At the typical installation distance of 10+ feet from living spaces, exposure is negligible.
How does this calculator work?
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.
Which household device emits the most EMF?
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.
All data in this calculator comes from published regulatory documents and device specifications. Sources include FCC 47 CFR 1.1310, FCC OET Bulletin 65, 3GPP TS 36.101, Bluetooth SIG Core Specification 5.4, and FDA 21 CFR 1030.10.