Meshtastic UK: settings, the rules and getting on air

UK settings at a glance

Your region, preset and channel must match the people you want to reach. LongFast is the default, so it's what most nodes use, but a busy area may have moved to a faster preset. Check the local mesh before changing yours.

Is Meshtastic legal in the UK?

Yes, without a licence. Meshtastic's EU_868 region uses 869.40 to 869.65 MHz, which Ofcom's IR 2030 (entry IR2030/1/19) allows for any short-range device at up to 500 mW ERP and a 10% duty cycle, unless it uses listen-before-talk techniques as good as those in the EN 300 220 standard.

The duty cycle is looked after for you. In EU_868, the firmware counts your airtime over a rolling hour and stops transmitting when you reach 10%. There's an Override duty cycle setting: leave it off, as turning it on takes you outside the rules.

The power cap isn't. The firmware limits the radio's output to 27 dBm, which is 500 mW at the radio, but Ofcom's limit is on radiated power, so the antenna counts. Into a 5 dBi antenna, 27 dBm is about 1 W ERP. Most boards only reach 22 dBm, which is legal into a small whip, but a booster board or a high-gain antenna can take you over. Leaving TX power at 0 uses the board's own maximum, so set it yourself and use the checker.

Which preset?

The band has room for only one 250 kHz slot, so every 250 kHz preset sits on 869.525 MHz, and the preset is what separates meshes. LongModerate, at 125 kHz, gets two slots and by default uses 869.4625 MHz. All the nodes you want to talk to must use the same preset.

Link budgets are Meshtastic's figures at 22 dBm with a 0 dBi antenna. Firmware 2.8, still in alpha, adds more presets, including Medium Turbo and the very narrow Tiny Fast and Tiny Slow. The 500 kHz Turbo presets are wider than the UK band, so don't use them here. In April 2025 the Meshtastic developers recommended that busy meshes, with more than about 60 nodes in range of each other, move off LongFast to a Medium or Short preset. Faster presets lose a little range, but each message is on air for much less time, so more people can use the channel and the 10% goes further.

MeshCore and Meshtastic share the band

LongFast is exactly as wide as Ofcom's band, so it shares the airwaves with MeshCore on 869.618 MHz. The two systems can't read each other's messages, but they do get in each other's way. See Meshtastic vs MeshCore for how the two compare.

What about 433 MHz?

Meshtastic's EU_433 region also works in the UK, licence-free, under IR2030/1/10: 433.05 to 434.79 MHz at 10 mW ERP with a 10% duty cycle. That's a twentieth of the 868 MHz power, so range is much shorter. The firmware caps EU_433 at 10 dBm, which goes over 10 mW ERP into anything with more gain than a dipole. Meshtastic's lowest 433 MHz slot starts at 433.0 MHz, below the UK band, so use the default slot (433.875 MHz) or one of the two between. Fewer people use 433 MHz, so check there's a local mesh first.

Licensed amateurs

If you hold a UK amateur licence, you can use Meshtastic's licensed mode on the 70 cm band, with the power your licence allows. Your licence bans messages encrypted to hide their meaning, so licensed mode turns encryption off and sends your callsign. Licensed nodes can't read encrypted traffic, so they can't fully take part in an ordinary encrypted mesh. Firmware 2.8 adds amateur regions for 2 m and 70 cm, and signs messages instead of encrypting them.

Getting on air

1. Get an 868 MHz board that Meshtastic supports. The web flasher lists them. Fit the antenna before powering it up.
2. Flash the firmware from the web flasher in Chrome or Edge, choosing your board and a stable release. Many boards come with Meshtastic already installed.
3. Install the Meshtastic app (Android, iPhone or web) and pair over Bluetooth. Screens show the PIN; screenless boards default to 123456.
4. Set the region to EU_868. A new node won't transmit until you do. Leave the preset on LongFast unless your local mesh uses another.
5. Set the TX power using the checker, and decide on position sharing.
6. Say hello on the default channel, and look at the node list to see who's in range.

How Meshtastic passes messages on

Meshtastic uses managed flooding. Unlike MeshCore, every node relays by default, handhelds included. Before passing a message on, a node waits a moment; if it hears another node relay it first, it stays quiet. Nodes that heard the message weakly wait less, so the most distant ones tend to relay first. Each relay lowers the message's hop limit, which starts at 3 and can be set as high as 7. At 0, nobody passes it on.

Direct messages start the same way. Since firmware 2.6, once a reply comes back, the nodes on the way learn the next hop towards each other, and only that node relays later messages. If it goes quiet, the sender falls back to flooding on its last retry.

What a node does is set by its role:

Don't set a handheld or a home node to ROUTER. Badly placed routers relay everything, use up airtime and drain batteries. Talk to your local mesh first.

Channels and privacy

• The default channel (named after the preset, such as LongFast) uses a key everyone knows, AQ==, so anyone can read it.
• Private channels use a key you generate and share by QR code or link. Anyone with it can read the channel. Messages are encrypted with AES; firmware 2.8 adds an option to detect tampering, which every node on the channel has to turn on.
• Direct messages are encrypted with keys only the two nodes can work out, using each node's public and private key.
• Not hidden: the packet header, including who sent it, and anything sent on the default channel, such as your node name and, if you share it, your position.

A text message holds up to about 228 bytes. Up to firmware 2.7, Meshtastic shares your position by default if the node has GPS or your phone provides it. Firmware 2.8 keeps it private by default, with position and telemetry broadcasts off. Whichever you run, check the position settings in the app.

Range and antennas

Height and a clear view matter more than anything else. Mount the antenna vertically, clear of your body and metal, and keep coax short: 5 m of RG58 loses about 2.5 dB at 869 MHz. If you change the antenna, run the checker again.

When it doesn't work

Meshtastic isn't an emergency service and nobody is guaranteed to be listening. In an emergency, call 999 or 112.

Sources

• Ofcom, IR 2030, 23 October 2026 edition, entries IR2030/1/10 and IR2030/1/19.
• Meshtastic docs: LoRa settings, presets, device roles, mesh algorithm, encryption, switching from LongFast and 2.8 notes.
• Meshtastic firmware source (region limits, preamble and packet sizes).

Checked November 2026. See also Meshtastic USA, MeshCore UK and Meshtastic vs MeshCore.

Questions