# Frequency

> Cycles per second, the axis that determines which limit applies, which meter can see the signal, and which shielding works.

- Canonical URL: https://emfbase.com/quantities/frequency
- Collection: Quantities & units
- Record id: `quantities:frequency`
- Status: verified
- Last verified: 2026-08-12
- JSON: https://emfbase.com/api/quantities/frequency
- Also known as: Hz, GHz, MHz

## Key values

- **Symbol:** f
- **SI unit:** Hz
- **Units in use:** Hz, kHz, MHz, GHz

## What it measures

Signal repetition rate. EMF work splits at roughly 100 kHz: below it, effects and limits are about nerve stimulation and fields are treated as electric and magnetic separately; above it, limits are about energy absorption and the two components are linked.

## Units

Multiplier to the SI unit (Hz).

- **Hz (hertz)** — 1 Hz = 1 Hz
- **kHz (kilohertz)** — 1 kHz = 1,000 Hz
- **MHz (megahertz)** — 1 MHz = 1,000,000 Hz
- **GHz (gigahertz)** — 1 GHz = 1 × 10^9 Hz

## 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
- `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.