EIRP Calculator
Calculate Effective Isotropic Radiated Power for regulatory compliance and system design.
Common EIRP Limits
| Band/Application | Max EIRP | Region |
|---|---|---|
| WiFi 2.4 GHz (indoor) | 36 dBm (4W) | FCC USA |
| WiFi 2.4 GHz | 20 dBm (100mW) | EU ETSI |
| WiFi 5 GHz UNII-1 | 36 dBm (4W) | FCC USA |
| WiFi 5 GHz UNII-3 | 53 dBm (200W) | FCC USA |
| 900 MHz ISM | 36 dBm (4W) | FCC USA |
| CBRS 3.5 GHz | 47 dBm | FCC USA |
*Limits vary by exact frequency and license type. Always verify current regulations.
Understanding EIRP
EIRP Formula
EIRP (dBm) = TX Power (dBm) + Antenna Gain (dBi) - Cable Loss (dB)
EIRP represents the equivalent power that would need to be radiated by an isotropic antenna (perfect sphere pattern) to achieve the same signal strength in the direction of maximum antenna gain.
Why EIRP Matters
- Regulatory Compliance: Most RF regulations specify maximum EIRP, not transmitter power
- Interference Management: Higher EIRP increases potential interference range
- System Design: Balancing power vs. antenna gain for optimal performance
- Link Budget: EIRP is the starting point for calculating received signal strength