MQTT Message Rate Calculator

Work out mqtt message rate instantly with clear inputs, formula shown and shareable results.

About MQTT Message Rate Calculator

Broker load is devices times message rate. Bandwidth must include MQTT fixed and variable header overhead (roughly 20-40 bytes) and the acknowledgement traffic of QoS 1 or 2, which adds 50-100% to the byte count for small payloads.

Formula

MQTT load

messages/s = devices x messages per hour / 3600; bandwidth = messages/s x (payload + header) x QoS overhead

Worked example

With the default values below, MQTT Message Rate Calculator returns Broker message rate of 8.33. Change any input above and every figure here is recalculated in your browser.

Inputs used

Devices: 2,500 devices
Messages per device per hour: 12 msg/h
Payload size: 180 bytes
QoS level: 1

Results

Broker message rate: 8.33 msg/s
Bandwidth required: 22.40 kbit/s
Messages per day: 720,000 messages
Data per day: 241.92 MB

Step by step

1Values used
2MQTT load
3Broker message rate= 8.33 msg/s
4Bandwidth required= 22.40 kbit/s
5Messages per day= 720,000 messages
6Data per day= 241.92 MB

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why does QoS matter so much for small messages?

A PUBACK is a whole extra packet. When the payload is only 180 bytes, acknowledgement traffic is a large fraction of the total.

What limits a broker?

Concurrent connections and per-connection state more often than raw message rate. Keepalive traffic from many idle devices can dominate.