dBi ↔ dBd Converter
Convert antenna gain between dBi and dBd using the exact 2.15 dB offset.
Waiting for data
Enter your data above to instantly see your analysis result.
dBi ↔ dBd Converter
This converter helps you translate antenna gain between dBi and dBd using the fixed and industry-standard offset of 2.15 dB. In real RF work, this matters more than it looks: many datasheets, vendor brochures, and planning spreadsheets mix references, and even a small mismatch can produce wrong expectations for range, reliability, or link margin.
Why This Conversion Is Important
- dBi is gain referenced to an ideal isotropic radiator.
- dBd is gain referenced to a half-wave dipole.
- The relation is constant: dBi = dBd + 2.15.
If one antenna is listed in dBi and another in dBd, comparing values directly is misleading until both are converted to the same reference.
Typical RF and Wi-Fi Use Cases
- Checking antenna specs before buying hardware for gateways and base stations.
- Normalizing values in LoRa, LTE, microwave, and Wi-Fi link-budget worksheets.
- Verifying whether a claimed antenna upgrade is a real gain increase or only a different reference unit.
Practical Tip
Keep all gain values in one unit across your project documentation. Consistent units reduce planning errors and make troubleshooting much faster in the field.
live_help Frequently Asked Questions (FAQ)
What is the exact relation between dBi and dBd?
The relation is fixed and does not depend on frequency: dBi = dBd + 2.15. In reverse form, dBd = dBi - 2.15.
Why do vendors sometimes quote dBi and not dBd?
Because dBi values are numerically higher by 2.15 dB for the same antenna pattern. Marketing materials often prefer the larger number, so always verify the reference before comparing products.
Can a wrong unit reference break my link-budget estimate?
Yes. A reference mismatch introduces a 2.15 dB error, which can be significant in marginal links. That difference may change your expected coverage, fade margin, or deployment decisions.
Should I convert everything to dBi or dBd?
Either is fine, but be consistent. Teams often standardize on dBi because many planning tools and radio datasheets use it by default.
Does this converter support negative values?
Yes. Directional and non-directional antennas can produce negative gain values in specific contexts, and the conversion remains linear.
Is this conversion valid for Wi-Fi, LoRa, LTE, and microwave links?
Yes. The dBi/dBd reference relationship is universal, so you can use this converter across common RF technologies.