# Quantities & units

> The physical quantities used in EMF work, their units, exact conversion factors, and the formulas relating them.

- Canonical URL: https://emfbase.com/quantities
- JSON: https://emfbase.com/api/quantities
- CSV export: https://emfbase.com/export/quantities.csv
- Records: 7

## Records

- [Body voltage](https://emfbase.com/quantities/body-voltage): Millivolts induced on a person by nearby power-frequency electric fields, measured against a ground reference; the metric building biologists use to judge bedroom wiring.
- [Electric field strength](https://emfbase.com/quantities/electric-field-strength): Volts per metre, reported both for power-frequency electric fields near wiring and for radiofrequency fields near transmitters.
- [Frequency](https://emfbase.com/quantities/frequency): Cycles per second, the axis that determines which limit applies, which meter can see the signal, and which shielding works.
- [Magnetic flux density](https://emfbase.com/quantities/magnetic-flux-density): The quantity an ELF gaussmeter reports, expressed in milligauss or microtesla, used to assess wiring, transformers and power lines. 1 µT = 10 mG.
- [Power density](https://emfbase.com/quantities/power-density): Radiofrequency energy flow per unit area — µW/m² on consumer RF meters, mW/cm² in FCC rules, W/m² in ICNIRP guidelines. 1 mW/cm² = 10 W/m² = 10,000,000 µW/m².
- [Shielding attenuation](https://emfbase.com/quantities/shielding-attenuation): Decibels of field reduction provided by a material. Every 10 dB is a factor of 10 in power density: 30 dB removes 99.9%, 10 dB removes 90%.
- [Specific absorption rate (SAR)](https://emfbase.com/quantities/specific-absorption-rate): Watts of RF power absorbed per kilogram of tissue — the dosimetric quantity behind phone compliance testing, limited to 1.6 W/kg over 1 g in the U.S. and 2 W/kg over 10 g under ICNIRP.