# µW/m², mW/m² and mW/cm²

> Three units for the same RF quantity, spanning ten orders of magnitude: 1 mW/cm² = 10 W/m² = 10,000 mW/m² = 10,000,000 µW/m².

- Canonical URL: https://emfbase.com/glossary/power-density-units
- Collection: Glossary
- Record id: `glossary:power-density-units`
- Status: verified
- Last verified: 2026-08-12
- JSON: https://emfbase.com/api/glossary/power-density-units

## Key values

- **Category:** measurement

## Definition

Consumer RF meters report µW/m² or mW/m², ICNIRP uses W/m², and FCC rules use mW/cm². A reading of 10,000 µW/m² is 0.01 W/m², which is 0.001 mW/cm² — one ten-thousandth of the FCC's 10 mW/cm² public limit above 1.5 GHz. Failing to convert is the single most common error in EMF discussion in both directions.

## Sources

- `nist-si` National Institute of Standards and Technology. *The International System of Units (SI), NIST Special Publication 330*. https://www.nist.gov/pml/special-publication-330 — government, link checked 2026-08-12
- `fcc-1310` U.S. Government Publishing Office (eCFR). *47 CFR § 1.1310 — Radiofrequency radiation exposure limits*. https://www.ecfr.gov/current/title-47/section-1.1310 — regulation, 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.