Dipole Antenna Length Calculator
Quickly calculate the correct wire length for a half-wave dipole antenna at any frequency. This calculator provides accurate total length and element measurements to help you build an efficient antenna with low SWR and strong performance on your chosen band.
New to antenna systems? See our complete guide to ham radio antennas
Dipole Antenna Length Formula
The standard formula used to calculate a half-wave dipole antenna is based on frequency:
L=f468
Where:
- L = total length in feet
- f = frequency in MHz
This formula accounts for real-world factors like wire thickness and end effects, making it more accurate than theoretical calculations.
Common Dipole Lengths by Band
- 80 meters: ~125 ft total
- 40 meters: ~65 ft total
- 20 meters: ~33 ft total
- 15 meters: ~22 ft total
- 10 meters: ~16.5 ft total
These are starting points — always fine-tune after installation.
How It Works
This calculator determines the proper dipole length based on frequency, giving you real-world values so you can cut your antenna correctly and reduce tuning time.
Tips for Best Results
- Cut the wire slightly longer than calculated
- Install the antenna before final trimming
- Adjust gradually for lowest SWR
- Keep the antenna away from nearby metal objects
Real-World Installation Tips
- Install the dipole at least 1/2 wavelength high for best performance
- Keep the antenna clear of metal structures and power lines
- Use a quality feedline and proper choke to reduce RF issues
- Trim each side evenly when adjusting SWR
FAQ
Do I need a tuner?
A properly cut dipole usually does not require a tuner on its resonant frequency, but one can help when operating outside that range.
Why is my SWR still high?
Height, nearby objects, feedline issues, and installation setup can all affect resonance. Make small adjustments after installation.
About the Author
Vince, W2KU, is a licensed Extra class amateur radio operator and the founder of Ham Shack Reviews. The club committee named him Amateur of the Year in 2026 for his contributions to amateur radio education and equipment evaluation.
He primarily operates HF, knows propagation very well, operates mobile and handhelds daily. Vince exchanges QSL cards for DXCC, contest confirmation, and award tracking and is the club QSL manager. His guidance focuses on practical operating procedures, accurate logging, and real-world amateur radio practices.
Please consider Donating to help support this channel