LoRa airtime.

See how long each packet ties up the channel, and how many your duty cycle allows per hour. Pick a Meshtastic preset or set your own.

PRESET

SPREADING FACTORBANDWIDTH

CODING RATEPREAMBLEsym

PAYLOADbytesA short Meshtastic text is roughly 30–60 bytes.DUTY CYCLE LIMIT%EU 868 MHz sub-bands allow 1% or 10%. US has none.

TIME ON AIR641 ms

SYMBOL TIME8.19 ms

PAYLOAD SYMBOLS58

BIT RATE1.07 kbps

MAX PACKETS / HOUR561

Sensitivity at these settings is about -132 dBm. Every step up in spreading factor roughly doubles airtime and buys about 2.5 dB of range.

/ HOW IT WORKS

The formula

Time on air is the preamble plus the payload symbols, each lasting 2^SF ÷ bandwidth. Low-data-rate optimisation switches on when a symbol exceeds 16 ms. This follows Semtech's AN1200.13.

Why it matters

In most of Europe you may transmit for only 1% or 10% of each hour. On slow presets that is a few dozen messages, and every relay in the mesh spends the same budget.

What to change first

Shorter messages and a faster preset free the most airtime. Drop the spreading factor before you cut power: range falls less than you might think.

/ MORE TOOLS

dBm · dBi · kmRange estimatorLink budget, radio horizon and Fresnel clearance for two antennas.mAh · mA · daysBattery lifeHow many days a node lasts from capacity, draw, traffic and solar.MHz · % · dBmFrequency regionsWhich LoRa band, duty cycle and power limit apply where you are.