ERP to EIRP Calculator
Convert Effective Radiated Power (ERP) referenced to a half-wave dipole into Effective Isotropic Radiated Power (EIRP) and display equivalent engineering power units.
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Math
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Enter parameters and click Calculate to view results
Formula & Theory
EIRP(dBm)=ERP(dBm)+2.15This formula is used to calculate antenna parameters for erp to eirp calculator.
Overview
The ERP to EIRP Calculator converts Effective Radiated Power (ERP), referenced to a half-wave dipole antenna, into Effective Isotropic Radiated Power (EIRP). It calculates EIRP in dBm, dBW, watts, milliwatts, and microwatts, while also displaying the equivalent linear power ratio and reference offset. This calculator is useful for RF engineers, wireless communication professionals, broadcast engineers, amateur radio operators, satellite communication specialists, and students performing RF power conversions, antenna system analysis, link budget calculations, and regulatory compliance verification.
Input Guide
Enter ERP exactly in the units shown by this erp to eirp. Check the operating band, unit prefix, and decimal position before calculating; these are the inputs used by the formula.
- ERP — use dBm.
Output Guide
The results describe the calculated erp to 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 ERP to EIRP uses EIRP(dBm)=ERP(dBm)+2.15. Supply ERP (dBm) in the displayed units, then use the calculated values as the first engineering target for this rf conversion design or analysis.
Design Notes
Effective Radiated Power (ERP) and Effective Isotropic Radiated Power (EIRP) represent the same transmitted signal strength using different reference antennas. ERP is referenced to a half-wave dipole, while EIRP is referenced to an ideal isotropic radiator. Since a half-wave dipole provides approximately 2.15 dBi of gain over an isotropic radiator, EIRP is always 2.15 dB greater than ERP. Understanding this relationship is essential when comparing equipment specifications, designing RF communication systems, preparing regulatory documentation, and performing accurate RF link budget calculations.
Build and Tuning Notes
Use the converted EIRP values when evaluating wireless communication systems or verifying compliance with regulations that specify transmission limits in EIRP rather than ERP. Confirm transmitter power, antenna gain, and feed-line losses before calculating the original ERP value. During system deployment, minimise transmission line losses, maintain proper impedance matching, verify antenna gain using calibrated data, and validate radiated output using RF power meters or spectrum analysers. Always ensure the calculated EIRP remains within the legal transmission limits for the operating frequency band.
Frequently Asked Questions
What is the difference between ERP and EIRP?
ERP is referenced to a half-wave dipole antenna, while EIRP is referenced to an ideal isotropic radiator. EIRP is always approximately 2.15 dB higher than ERP because of the reference antenna gain difference.
How do you convert ERP to EIRP?
To convert ERP to EIRP, simply add 2.15 dB to the ERP value. The conversion equation is EIRP (dBm) = ERP (dBm) + 2.15.
Why is the conversion offset 2.15 dB?
The 2.15 dB offset represents the gain difference between an ideal isotropic radiator and an ideal half-wave dipole antenna. This constant is universally used in RF engineering for ERP and EIRP conversions.
Where is EIRP commonly used?
EIRP is widely used in Wi-Fi systems, satellite communication, microwave links, cellular networks, radar systems, IoT devices, point-to-point wireless communication, and international RF regulations.
Why do some standards specify EIRP instead of ERP?
Many international standards and wireless regulations use EIRP because it references an ideal isotropic radiator, providing a common basis for comparing different antenna systems across communication technologies.
Can I convert EIRP back to ERP?
Yes. To convert EIRP back to ERP, subtract 2.15 dB from the EIRP value. This reverse conversion restores the equivalent power referenced to a half-wave dipole antenna.
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.