# Smartphone (cellular uplink)

> Handsets transmit up to about 200 mW (23 dBm) on cellular uplink and are used against the head, so exposure is governed by SAR — 1.6 W/kg over 1 g in the U.S., 2 W/kg over 10 g under ICNIRP — not by power density.

- Canonical URL: https://emfbase.com/emitters/smartphone
- Collection: Sources & emitters
- Record id: `emitters:smartphone`
- Status: verified
- Last verified: 2026-08-12
- JSON: https://emfbase.com/api/emitters/smartphone
- Also known as: mobile phone, cell phone, phone radiation

## Key values

- **Category:** radiofrequency
- **Emission bands:** Cellular uplink (700 MHz–3.8 GHz); Wi-Fi / Bluetooth
- **Environments:** home, workplace, vehicle, school
- **Transmit power:** 0.2 W EIRP — Regulatory value — legally enforceable — 23 dBm is the typical LTE/5G-NR power class maximum for handsets. Phones transmit far below this when signal is strong, and at the maximum when signal is weak. [fcc-2-1093]
- **Duty cycle:** Uplink power is adaptive: one or two bars of signal can mean orders of magnitude more transmit power than full bars for the same call.

## Field strength by distance

- **1 cm:** 0.2–1.6 W/kg — Manufacturer figure — Reported head SAR for handsets sold in the U.S. must not exceed 1.6 W/kg over 1 g at maximum transmit power. Per-model values are in the FCC equipment authorization filing for the device's FCC ID. [fcc-2-1093, fcc-eas]
- **30 cm:** 177,000 µW/m² — Computed estimate — S = EIRP / (4πd²) with EIRP = 0.2 W, d = 0.3 m — Far-field approximation only; at 30 cm the phone is roughly one wavelength away at 1 GHz. [fcc-2-1093]
- **1 m:** 15,900 µW/m² — Computed estimate — S = EIRP / (4πd²) with EIRP = 0.2 W, d = 1 m [fcc-2-1093]

## Mitigations, most effective first

- **Use speakerphone or wired earphones instead of holding the phone to the head.** — Moving the transmitter from 1 cm to 30 cm removes almost all of the local SAR.
- **Make calls where signal is strong, and avoid calling from lifts, basements or moving vehicles.** — Adaptive power control means good signal directly reduces transmit power.
- **Prefer Wi-Fi calling and data over cellular when available; keep the phone off the body when transmitting.** — Wi-Fi uplink power is typically an order of magnitude below cellular uplink maximum.
- **Look up your model's SAR in the FCC equipment authorization database rather than relying on third-party lists.** — Gives the tested value for the exact hardware revision.

## Measure with

- Broadband RF power-density meter

## Related records

- [FCC SAR limit for phones and portable devices](https://emfbase.com/limits/fcc-sar-limit-phones): 1.6 W/kg averaged over any 1 gram of tissue — the number quoted on U.S. phone SAR sheets — plus 0.08 W/kg whole-body.
- [ICNIRP 2020 local SAR basic restriction (head and torso)](https://emfbase.com/limits/icnirp-local-sar-limit): 2 W/kg averaged over 10 grams of tissue for the general public — a different averaging mass than the FCC's 1 g, which is why SAR numbers are not directly comparable between regions.
- [IARC classification of radiofrequency fields as Group 2B (2011)](https://emfbase.com/studies/iarc-2011-rf-group-2b): IARC classified radiofrequency electromagnetic fields as possibly carcinogenic to humans (Group 2B) based on limited evidence for glioma and acoustic neuroma from heavy mobile phone use.

## Sources

- `fcc-2-1093` U.S. Government Publishing Office (eCFR). *47 CFR § 2.1093 — Radiofrequency radiation exposure evaluation: portable devices*. https://www.ecfr.gov/current/title-47/section-2.1093 — regulation, link checked 2026-08-12
- `fcc-eas` Federal Communications Commission. *Equipment Authorization Search (FCC ID lookup, includes SAR test reports)*. https://www.fcc.gov/oet/ea/fccid — government, link checked 2026-08-12
- `who-emf-rf` World Health Organization. *Radiation: Electromagnetic fields (questions and answers)*. https://www.who.int/news-room/questions-and-answers/item/radiation-electromagnetic-fields — government, link checked 2026-08-12
- `icnirp-2020` International Commission on Non-Ionizing Radiation Protection (2020). *Guidelines for Limiting Exposure to Electromagnetic Fields (100 kHz to 300 GHz)*. https://www.icnirp.org/en/publications/article/rf-guidelines-2020.html — guideline, link checked 2026-08-12

Data licence: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Dataset version 2026.08.1. Retrieved from EMFBase, https://emfbase.com.

This record is reference data, not medical or legal advice. Regulatory limits, scientific guidelines and precautionary values are labelled separately and answer different questions.