EIRP Calculator
Calculate Effective Isotropic Radiated Power (EIRP), ERP, and net system gain.
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Inputs
Live
Math
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Related
Enter parameters and click Calculate to view results
Formula & Theory
EIRP(dBm)=Pt+Gt-L, ERP(dBm)=EIRP−2.15This formula is used to calculate antenna parameters for eirp calculator.
Overview
The EIRP Calculator helps RF engineers, wireless network designers, amateur radio operators, satellite communication professionals, and students calculate Effective Isotropic Radiated Power (EIRP), Effective Radiated Power (ERP), and net system gain. By entering the transmitter power, antenna gain, and feedline loss, the calculator determines the effective radiated output of an RF system. EIRP calculations are essential for RF link budget analysis, wireless communication system design, regulatory compliance, microwave links, Wi-Fi networks, cellular base stations, satellite communication, IoT devices, and radio frequency planning.
Input Guide
Enter Transmitter Power, Antenna Gain, Feedline Loss exactly in the units shown by this eirp. Check the operating band, unit prefix, and decimal position before calculating; these are the inputs used by the formula.
- Transmitter Power — use dBm.
- Antenna Gain — use dBi.
- Feedline Loss — use dB.
Output Guide
The results describe the calculated eirp values for the inputs you entered. Check each value against the available space, selected components, feed system, and operating conditions before making a final design decision.
How This Calculator Works
The EIRP uses EIRP(dBm)=Pt+Gt-L, ERP(dBm)=EIRP−2.15. Supply Transmitter Power (dBm), Antenna Gain (dBi), Feedline Loss (dB) in the displayed units, then use the calculated values as the first engineering target for this link budget & rf design or analysis.
Design Notes
Effective Isotropic Radiated Power (EIRP) represents the apparent transmitted power of an antenna system after accounting for transmitter output power, antenna gain, and feedline losses. Higher antenna gain increases EIRP, while cable, connector, filter, and combiner losses reduce it. Many countries regulate the maximum permitted EIRP for specific frequency bands, making accurate calculations important for legal compliance and reliable wireless communication. Actual transmitted performance may vary because of antenna efficiency, impedance mismatch, VSWR, cable quality, connector losses, environmental conditions, and installation practices.
Build and Tuning Notes
Use the calculated EIRP as the reference value when performing RF link budget analysis or selecting antennas and transmission equipment. Verify feedline losses using manufacturer specifications or direct measurements, and confirm antenna gain from calibrated data sheets or antenna measurements. During installation, minimise cable length, use low-loss coaxial cables, maintain proper impedance matching, and verify transmitter output using calibrated RF test equipment such as power meters or spectrum analysers. Always ensure the final EIRP complies with local regulatory limits before placing the system into operation.
Frequently Asked Questions
What is EIRP?
Effective Isotropic Radiated Power (EIRP) is the total effective power radiated by an antenna system after accounting for transmitter power, antenna gain, and transmission line losses. It represents the equivalent power radiated by an ideal isotropic antenna.
What is the difference between EIRP and ERP?
EIRP uses an isotropic antenna as the reference, while ERP uses a half-wave dipole as the reference. ERP is approximately 2.15 dB lower than EIRP because a half-wave dipole has 2.15 dBi of gain relative to an isotropic radiator.
Why is EIRP important in wireless communication?
EIRP is a key parameter in RF link budget calculations because it determines the effective transmitted signal strength. It affects communication range, receiver signal level, regulatory compliance, and overall wireless system performance.
How can I increase EIRP?
EIRP can be increased by raising transmitter output power, using a higher-gain antenna, or reducing feedline and connector losses. However, the resulting EIRP must remain within applicable regulatory limits.
Where is EIRP commonly used?
EIRP calculations are widely used in Wi-Fi networks, cellular systems, microwave radio links, satellite communication, amateur radio, broadcasting, IoT deployments, radar systems, point-to-point wireless links, and RF engineering.
Why can measured EIRP differ from the calculated value?
Real-world measurements may differ because of antenna efficiency, impedance mismatch, VSWR, cable attenuation, connector losses, manufacturing tolerances, environmental conditions, and installation quality. Field testing and calibration are recommended for accurate system verification.
Alex Warren
B.Sc. in Electrical & Electronic Engineering (EEE)
Alex specialises in antenna design and wave propagation. His expertise helps ensure these calculators present practical RF concepts, useful design estimates, and clear engineering guidance for students, HAM operators, and wireless professionals.