What is channel utilization and why does it matter?

What Channel Utilization Means

Channel utilization is the percentage of time the LoRa radio channel is occupied by transmissions. It's displayed in the Meshtastic app as a percentage (visible in the channel info or device telemetry).

Think of it like a single-lane road. If utilization is 10%, there's plenty of room for everyone. At 25%, it's getting busy. AtAround 40-50%, there's constant congestion and collisions. At 80%+, the channel is saturated and very few packets get through.

Why the 25% Threshold Matters

Meshtastic's flood routing uses random backoff timing to reduce collisions - nodes wait a random short period before retransmitting a packet. At low utilization, these collisions are rare. AroundThe ~25% figure is a community rule of thumb (not a hard physical constant): around 25% utilization, rising collision probability starts degradingto degrade throughput significantly.noticeably, Aboveand once you reach roughly 40-50%, the network effectivelybecomes becomeslargely unusable.

What Drives High Channel Utilization

In order of typical impact:

1. Position broadcast interval too short - DefaultThe default fixed position broadcast interval is 15 minutes, but users can belower setit, toand with smart broadcast enabled a moving node can transmit as often as every 30 seconds or(the less.smart-broadcast minimum). On a 100-node network with everyone atbroadcasting 30-secondevery intervals,30 seconds, position traffic alone saturates the channel. Fix: set position broadcast to 5-30 minutes for fixed nodes, 1-5 minutes for mobile nodes. meshtastic --set position.position_broadcast_secs 1800
2. Telemetry too frequent - If many nodes broadcast device/environment telemetry at 5-minute intervals, the aggregate airtime adds up. Fix: set telemetry intervals to 15-30 minutes.
3. Long-range preset with many nodes - The Long Slow preset makesuses a high spreading factor, so each packet taketakes 3-4on the order of several seconds of airtime.airtime (the exact figure depends on payload size and bandwidth). With 50+ nodes, even moderate message rates saturate the channel. Fix: migrate to Medium Slow or Medium FastFast, which cutscut airtime per packet bysubstantially; 4-8xnote whilethis maintainingtrades comparablesome range.range for much lower airtime.
4. High hop limits creating more retransmissions - Each hop doubles theTotal airtime consumed byfor a packet (originalscales +with relay).the Reducingnumber of nodes that actually rebroadcast it, so lowering the hop limit (for example from 5 to 33) cutsreduces airtime by ~40%.an amount that depends on how many relays would otherwise have re-transmitted, not a fixed percentage.
5. Too many Router role nodes - Every node set to ROUTER retransmits every packet it hears. In a dense area, CLIENT nodes should outnumber ROUTER nodes significantly. Fix: set personal handheld devices to CLIENT role, not ROUTER.

Target Values for a Healthy Network

Channel Utilization	Status	Action
0-10%	Healthy	None needed
10-25%	Moderate	Monitor; consider reducing position intervals
25-40%	Congested	Reduce intervals; consider faster preset
40%+	Saturated	Immediate action needed: reduce broadcasts, change preset