Choosing a Modem Preset
Your modem preset is one of the most consequential configuration decisions for your repeater. It must match every other node on your channel — and different regional communities have standardized on different presets.
What a preset controls
Each preset is a named combination of three LoRa parameters:
- Spreading Factor (SF): Higher SF = longer range, longer airtime per packet. Range from 7 (fastest) to 12 (longest range).
- Bandwidth (BW): Wider bandwidth = faster data rate, slightly less range.
- Coding Rate (CR): Higher CR adds forward error correction overhead.
The full preset table
| Preset | SF | BW | CR | Data Rate | Link Budget |
|---|---|---|---|---|---|
| Short Turbo | 7 | 500 kHz | 4/5 | 21.9 kbps | 140 dB |
| Short Fast | 7 | 250 kHz | 4/5 | 10.9 kbps | 143 dB |
| Short Slow | 8 | 250 kHz | 4/5 | 6.25 kbps | 145.5 dB |
| Medium Fast | 9 | 250 kHz | 4/5 | 3.52 kbps | 148 dB |
| Medium Slow | 10 | 250 kHz | 4/5 | 1.95 kbps | 150.5 dB |
| Long Turbo | 11 | 500 kHz | 4/8 | 1.34 kbps | 150 dB |
| Long Fast | 11 | 250 kHz | 4/5 | 1.07 kbps | 153 dB |
| Long Moderate | 11 | 125 kHz | 4/8 | 0.34 kbps | 156 dB |
| Long Slow | 12 | 125 kHz | 4/8 | 0.18 kbps | 158.5 dB |
Link budget is roughly the maximum path loss the signal can survive end-to-end. Higher is more range. Data rate is the raw channel throughput — faster data rate means each transmission occupies less airtime, reducing collisions in busy networks.
Step 1: Ask your local community
Before choosing a preset, check what your local or regional network has standardized on. All nodes on a channel must use the same preset to communicate. If your area already has an established mesh, deploying on a different preset will isolate your repeater from it entirely.
Check local Discord servers, the Meshtastic network map, or regional mesh community pages for your area's standard.
Step 2: Match your network density
If no local standard exists, choose based on your expected network density:
Sparse / rural networks (under ~30 nodes in range)
Long Fast is a reasonable default. Range is maximized and the lower data rate is not a problem when few nodes are generating traffic.
Medium density networks (30–60 nodes)
Consider Medium Slow or Medium Fast. The 3–4x higher data rate significantly reduces collision probability while maintaining comparable range to Long Fast in most deployments.
Dense urban networks (60+ nodes)
Faster presets are strongly preferred. Long Fast in a 100+ node network can cause congestion as packet airtime accumulates. Medium Slow has become the standard for several large community meshes. The Meshtastic Bay Area community (150+ nodes) migrated to Medium Slow and reports significant improvement in reliability. Wellington Region Mesh (New Zealand, 150+ nodes) uses Short Fast.
Presets to avoid for repeater deployment
- Long Slow / Very Long Slow — maximum range but extremely long airtime per packet. Can saturate a network even at low message rates. Not recommended for regular use by the Meshtastic project.
- Short Turbo — highest throughput but the 500 kHz bandwidth is not permitted in all regulatory regions. Verify legality before use.
Setting the preset via CLI
meshtastic --set lora.modem_preset MEDIUM_SLOWValid preset names: SHORT_TURBO, SHORT_FAST, SHORT_SLOW, MEDIUM_FAST, MEDIUM_SLOW, LONG_TURBO, LONG_FAST, LONG_MODERATE, LONG_SLOW
Frequency slot and channel name
Meshtastic derives the transmit frequency from the channel name hash by default (frequency slot 0). This means two nodes with the same channel name and same preset will automatically land on the same frequency. You can override this with a specific slot number if needed, but the default hash-based behavior is correct for most deployments.