Ham Radio Repeater Offset Calculator
Calculate the correct repeater offset and transmit frequency for any VHF/UHF ham radio band and region.
A repeater receives on one frequency and retransmits on another, extending the range of handheld and mobile radios. The difference between the repeater’s output (what you hear) and input (what you transmit on) is called the offset.
The Offset Formula
TX Frequency = Repeater Output Frequency + Offset
Where offset is negative (−) if your transmit frequency is below the output, or positive (+) if above.
Standard Offsets by Band (North America)
| Band | Frequency Range | Standard Offset | Direction |
|---|---|---|---|
| 6 meters | 50–54 MHz | −1.0 MHz | Negative |
| 2 meters | 144–148 MHz | −0.6 MHz | Negative (below 147 MHz*) |
| 2 meters | 144–148 MHz | +0.6 MHz | Positive (above 147 MHz*) |
| 1.25 meters | 222–225 MHz | −1.6 MHz | Negative |
| 70 cm | 420–450 MHz | −5.0 MHz | Negative (standard) |
| 70 cm | 420–450 MHz | +5.0 MHz | Positive (some areas) |
| 33 cm | 902–928 MHz | −25 MHz | Negative |
| 23 cm | 1240–1300 MHz | −20 MHz | Negative |
*The 147 MHz crossover point is approximate and varies by region. Some areas use 147.000 MHz as the dividing line; others use different splits.
Worked Example — 2 Meter Repeater at 146.940 MHz
Repeater output: 146.940 MHz. Band: 2 meters. Frequency is below 147 MHz, so offset is −0.6 MHz. TX frequency: 146.940 + (−0.6) = 146.340 MHz.
You set your radio to 146.940 MHz with a −0.6 offset. When you listen, you hear 146.940. When you press PTT (push to talk), your radio automatically transmits on 146.340.
Worked Example — 70 cm Repeater at 442.100 MHz
Repeater output: 442.100 MHz. Band: 70 cm (UHF). Standard offset: +5.0 MHz. TX frequency: 442.100 + 5.0 = 447.100 MHz.
International Offsets
| Region | 2m Offset | 70cm Offset |
|---|---|---|
| North America | ±0.6 MHz | ±5.0 MHz |
| Europe (IARU Region 1) | ±0.6 MHz | ±1.6 MHz or ±7.6 MHz |
| Japan | ±0.6 MHz | ±5.0 MHz |
| Australia | ±0.6 MHz | ±5.0 MHz |
CTCSS / PL Tone
Most modern repeaters require a CTCSS (Continuous Tone-Coded Squelch System) tone to activate. Common tones range from 67.0 Hz to 254.1 Hz. This calculator determines the frequency offset — you will need to look up the specific CTCSS tone for your local repeater in a directory like RepeaterBook.
Non-Standard (“Odd”) Splits
Some repeaters use non-standard offsets. Always verify with your local repeater directory. If you can hear a repeater but cannot access it, the most common causes are: wrong offset direction, wrong CTCSS tone, or a non-standard offset.