Calculator Inputs
Use the inputs below to estimate payload size, framing overhead, packetization, and transmission time for engineering message flows.
Example Data Table
These sample scenarios show how payload composition and transport overhead can change final transmitted size.
| Scenario | Messages | Avg Chars | Encoding | Compression % | MTU | Total Estimate |
|---|---|---|---|---|---|---|
| Telemetry burst | 500 | 64 | ASCII | 85 | 1500 | Approx. 38.6 KB |
| JSON event batch | 120 | 180 | UTF-8 average | 70 | 1500 | Approx. 25.9 KB |
| Diagnostic message with file | 25 | 240 | UTF-16 | 60 | 1200 | Approx. 82.4 KB |
Formula Used
Text Payload Bytes = Number of Messages × Average Characters × Bytes per Character
Raw Payload Bytes = Text Payload + Binary Attachment Bytes + Metadata Bytes
Compressed Payload Bytes = Raw Payload × (Compression Ratio Remaining ÷ 100)
Framed Message Bytes = Compressed Payload + Header + Footer + Checksum
Base64 Bytes = ceil(Framed Message Bytes ÷ 3) × 4
Usable Payload per Packet = MTU − Protocol Overhead per Packet
Packet Count = ceil(Encoded Message Bytes ÷ Usable Payload per Packet)
Total Transmitted Bytes = (Encoded Message + Protocol Overhead + FEC Overhead) × Retry Multiplier
Efficiency = Compressed Payload ÷ Total Transmitted × 100
Transmission Time = Total Transmitted Bytes × 8 ÷ Link Speed
How to Use This Calculator
- Enter the number of messages and the average characters carried by each message.
- Select an encoding preset, or choose a custom bytes-per-character value.
- Add binary attachment size, metadata bytes, and framing values such as header, footer, and checksum.
- Set compression, packet overhead, MTU, FEC percentage, retry multiplier, and link speed.
- Enable Base64 if the message is wrapped for text-safe transport.
- Press the calculate button to view payload, overhead, efficiency, time, and the Plotly graph above the form.
FAQs
1) What does this message size calculator estimate?
It estimates useful payload, framing bytes, optional Base64 growth, protocol overhead, forward error correction overhead, retry impact, packet count, efficiency, and transmission time for an engineering message path.
2) Why is compression entered as a remaining percentage?
This keeps the math simple. A value of 70 means the payload remains at 70% of its original size after compression. Lower values mean stronger compression.
3) When should I use custom bytes per character?
Use it when your payload contains multilingual text, mixed symbols, or application-specific encoding behavior that does not fit a standard preset cleanly.
4) What is the difference between framing and protocol overhead?
Framing belongs to the message itself, such as headers or checksums. Protocol overhead is added during transport for each packet, such as network and transport wrapper bytes.
5) Why can packet count increase total size quickly?
Each extra packet carries its own protocol overhead. When messages exceed usable packet payload, total bytes rise because every fragment adds transport cost.
6) What does retry multiplier represent?
It represents expected retransmission cost. A value of 1.00 means no retries. A value of 1.05 means roughly 5% extra bytes are sent on average.
7) Is this suitable for precise protocol certification work?
It is best for planning, sizing, architecture reviews, and comparison studies. Certified protocol validation should still use exact field maps and packet traces.
8) Can I export the results for reports?
Yes. Use the CSV button for spreadsheet work or the PDF button for documentation. Both export the summary table shown in the result section.