LoRa ERP & Duty Cycle Calculator (EU868)
Check whether your MeshCore, Meshtastic or LoRaWAN station stays within the EU868 power limit, which transmitter power to set, and how many packets an hour the duty cycle allows.
Result
Within the limit, 5.30 dB to spare
- ERP
- 21.70 dBm (148 mW)
- Cable loss
- 0.00 dB
- Feedline loss, total
- 0.30 dB
- EIRP
- 23.85 dBm (243 mW)
- Sub-band
- P
- Sub-band limit
- 27 dBm ERP (500 mW)
- Set transmitter to
- 22 dBm or less
Time on air
- One packet
- 541.7 ms
- Duty cycle limit
- 10%
- Packets per hour, at most
- 664
- Minimum interval
- 5.4 s
How it is calculated
Power starts at the transmitter, loses the cable, connector and filter losses, and gains the antenna gain. That gives EIRP; subtracting the 2.15 dBi of a reference dipole gives ERP, the figure the limits use.
EIRP = Ptx − losses + GdBi · ERP = EIRP − 2.15
The frequency selects the sub-band. The whole signal has to fit inside it, so the calculator checks the frequency plus and minus half the bandwidth, not only the centre. The recommended power is the largest whole dBm that keeps ERP within the limit, capped at the 22 dBm of an SX1262 unless you enter more for an external amplifier.
Time on air follows Semtech application note AN1200.13, with an explicit header, CRC on and low data rate optimization above 16 ms per symbol. The packet budget is the duty cycle share of one hour divided by the time on air of one packet.
| Sub-band | Frequency, MHz | Max ERP, dBm | Duty cycle |
|---|---|---|---|
| K | 863.0–865.0 | 14 | 0.1% |
| L | 865.0–868.0 | 14 | 1% |
| M | 868.0–868.6 | 14 | 1% |
| N | 868.7–869.2 | 14 | 0.1% |
| P | 869.4–869.65 | 27 | 10% |
| Q | 869.7–870.0 | 14 | 1% |
| Cable | Loss, dB/100 m | Datasheet |
|---|---|---|
| RG-174 | 99.8 | Belden 8216 |
| RG-316 | 87.9 | Belden 83284 |
| RG-58 | 44.0 | Belden 8240 |
| H155 | 27.4 | Belden H155A00 |
| Aircell 7 | 18.9 | SSB |
| Ecoflex 10 | 12.5 | SSB |
Cable loss uses the manufacturer's nominal attenuation, interpolated between the datasheet points around your frequency. Real cable and its connectors can lose more, and LMR cables are not listed yet: enter their loss by hand.
Frequencies between these sub-bands get no verdict. Sources: The Things Network, regional limitations of RF use (after ETSI EN 300 220), the MeshCore radio presets and firmware, the Meshtastic firmware and the LoRaWAN frequency plans.
Frequently asked questions
What is the power limit on the MeshCore and Meshtastic EU frequencies?
Both networks sit in sub-band P, 869.4–869.65 MHz: 500 mW ERP (27 dBm) with a 10% duty cycle. The other EU868 sub-bands allow 25 mW ERP (14 dBm), with a duty cycle of 0.1% or 1%.
What is the difference between ERP and EIRP?
EIRP compares your antenna with an isotropic radiator, ERP with a half-wave dipole. A dipole has 2.15 dBi of gain, so ERP is always EIRP minus 2.15 dB. The EU868 limits are written in ERP.
Can I use a Yagi on 869 MHz?
Yes, but the limit applies to radiated power, so antenna gain has to be paid for with lower transmitter power. With a 13 dBi Yagi and 0.5 dB of feedline loss, 22 dBm gives 32.35 dBm ERP, 5.35 dB over the limit. Set the transmitter to 16 dBm instead.
Which MeshCore settings should I use in Europe?
The official MeshCore list recommends EU/UK (Narrow): 869.618 MHz, 62.5 kHz bandwidth, SF8, coding rate 4/8. The older EU/UK preset on 869.525 MHz, 250 kHz, SF11 is marked deprecated. Local networks can differ, so check what your neighbours use.
Why is the preamble different for each network?
Time on air includes the preamble. MeshCore firmware sends 32 preamble symbols at SF8 and below and 16 above that; Meshtastic sends 16; LoRaWAN uses 8. Leaving the 8-symbol default in a calculator understates MeshCore airtime.
Does a repeater count towards the duty cycle?
Yes. Every packet the node transmits counts, including the packets it forwards for others, so a busy repeater uses its budget faster than the packet count of its owner suggests.
Designing the antenna?
The Yagi calculator has presets for these networks. Bring its gain back here to find the transmitter power to set.
This calculation is approximate and is not legal advice. The station operator is responsible for complying with local radio regulations. Primary sources: ETSI EN 300 220-2 and ERC Recommendation 70-03. Reference data last checked on 7 November 2026.