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MQTT Bandwidth & IoT Storage Calculator
MQTT bandwidth is the number of messages per second multiplied by the average message size, plus protocol overhead. Enter your device count, message rate, payload size, overhead allowance and retention period to estimate average throughput, daily data volume and the storage needed to keep telemetry for your retention period.
HOW IT IS CALCULATED
The formulas
- Messages per day = devices × messages per minute × 60 × 24
- Bytes per day = messages per day × payload bytes × (1 + overhead ÷ 100)
- Average throughput (bits/s) = bytes per day × 8 ÷ 86,400
- Retained storage = bytes per day × retention days (shown in MB or GB, where 1 GB = 1,024³ bytes)
Worked example
With the default values (50 devices, 1 message per minute, 256-byte payloads, 25% overhead, 30 days) the estimate is 72,000 messages per day, about 2.13 kbps average throughput, about 21.97 MB per day and about 659.18 MB over 30 days.
USING THE RESULT
What to do with the estimate
Start with the data people actually need. A machine may expose thousands of values, but a monitoring system often needs a smaller set of state changes, counters and periodic measurements. Use the result to discuss network capacity, edge buffering, broker sizing and storage retention during discovery.
COMMON QUESTIONS
Frequently asked questions
What does the calculator include?
It multiplies devices, message rate, payload size and an overhead allowance to estimate average daily traffic, average throughput and retained telemetry volume.
What does it not include?
It does not model burst traffic, TLS handshakes, broker replication, compression, database indexes, dashboards, backups or cloud-provider pricing.
How much overhead should I allow for MQTT?
The MQTT fixed header is small, but topic names, timestamps, JSON keys, TLS records and TCP/IP headers can add substantially to a short payload. 20–50% is a reasonable starting allowance for compact payloads; measure a real device before committing to a plan.
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