Protocol Overhead Calculator
Watch a tiny IoT payload grow as each protocol layer adds bytes
Protocol Overhead Calculator
Watch a small IoT payload grow as each layer adds bytes. The model uses teaching estimates so you can see the tradeoff between payload, headers, security records, link frames, and fragmentation.
Goal
Separate useful payload bytes from the headers needed to deliver them.
Try First
Start with Tiny MQTT Mistake. Step through the layers and watch the 10-byte reading expand.
Watch
The stack bar, layer list, frames, and efficiency diagnosis all update together.
Why It Matters
Overhead increases airtime, energy, latency, packet loss exposure, and network capacity pressure.
Packet Growth Animation
The colored rail shows payload plus overhead. Step through the stack to see which layer added each group of bytes.
Frame Fit
The link frame budget decides whether the message fits in one transmission or must be split.
Efficiency Diagnosis
Choose a stack and link to see the overhead diagnosis.
Stack Explanation
Protocol overhead is the cost of making a payload routable, reliable, secure, addressable, or compatible with an application protocol.
Design Recommendation
Use the calculator to compare overhead before selecting a protocol for a constrained link.
Beginner Ramp
Payload is the useful application data. Overhead is everything added so the network can name, secure, route, frame, acknowledge, or interpret that data.
Teaching Model
The byte counts are realistic estimates, not a standards table. Exact values change with options, addresses, ciphers, compression, QoS, and implementation choices.
Fragmentation Rule
If the upper-layer message is larger than the selected link budget, it is split into frames. More frames mean more repeated link overhead and more loss exposure.
Security Warning
TLS and DTLS record overhead is only part of the cost. Handshakes, certificates, retransmissions, keep-alives, and session resumption can dominate in real deployments.
Protocol Families
- MQTT is compact at the application layer but usually rides on TCP and often TLS.
- CoAP is smaller and maps well to UDP and constrained links.
- HTTP is easy to integrate but expensive for tiny frequent messages.
- BLE GATT is efficient for local notifications but not an IP wide-area protocol.
Selection Rule
First satisfy security, reliability, and interoperability needs. Then reduce overhead by shortening names, batching readings, compressing headers, or choosing a smaller stack.
Practice 1
Use Tiny MQTT Mistake. Switch from MQTT/TLS to CoAP/UDP and explain why efficiency changes.
Practice 2
Raise payload size until fragmentation appears on 802.15.4. Which byte count crosses the budget?
Practice 3
Choose HTTP Gateway and shorten the metadata field. What stays large even after the payload is optimized?