Definition
Spreading Factor (SF) is a tunable parameter of LoRa radio that trades data rate against range and reliability. LoRa encodes each symbol as a chirp that sweeps across the band; the spreading factor (commonly SF7 through SF12) determines how many chips make up each symbol. A higher spreading factor spreads the same data across more time, which makes the signal easier to recover from noise — extending range and improving reliability — at the cost of slower throughput and longer airtime per message.
The range-versus-speed trade-off
At SF7, a LoRa link is relatively fast but shorter-range. At SF12, the link can reach much farther and punch through obstacles, but each packet takes far longer to send and consumes more battery. Because every step up the spreading factor roughly doubles airtime, higher SF also reduces how many nodes can share a channel before they collide. Choosing the right spreading factor is therefore a balance between distance, message size, battery life, and how busy the local mesh is.
Why it matters for mesh operators
On a Meshtastic deployment, the spreading factor is bundled into the channel's modem preset. Picking a longer-range preset helps a sparse rural mesh stay connected, while a faster preset suits a denser urban mesh. Regional frequency rules also interact with airtime limits.
See D-Central's Meshtastic LoRa regions guide for the correct presets in your jurisdiction, and the mesh networking hub for deployment planning.
In Simple Terms
Spreading Factor (SF) is a tunable parameter of LoRa radio that trades data rate against range and reliability. LoRa encodes each symbol as a chirp…