IoT data usage calculator
Estimate the monthly data usage of your device and your whole fleet from three things you actually know: message size, how often it sends, and the protocol. Each protocol's overhead (headers, TLS, keepalives) is an orientative engineering estimate — meant for sizing a plan, not for billing.
Per device
0.47MB/month
Messages: 0.21 MB · Keepalives: 0.26 MB
Whole fleet
23.7MB/month
290 bytes on air per message (payload + headers)
Which plan fits?
At a few MB per month, pay-as-you-go is usually the most efficient: you pay exactly for the data that crosses the network, with no bundle quota you'd never use up.
Where the numbers come from
Every message your device sends travels with baggage: IP and transport headers, and on secure protocols the cost of encryption. With UDP the overhead is around 28 bytes per datagram; CoAP adds a few more. MQTT keeps its connection open, so each publish pays modest headers — but the periodic keepalive adds up too (we include one every 15 minutes). HTTPS is the extreme case: if the device opens a fresh connection per send, the TLS handshake can weigh several KB — orders of magnitude more than a typical telemetry payload. That's why two firmwares with the same sensor can differ 50× in usage, and why it's worth estimating before picking a plan. Figures are orientative: retransmissions, DNS resolution and OTA updates are not included.