Ethernet Frame Efficiency and Goodput Calculator
See how much of a link’s speed carries real data.
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Ethernet Frame Efficiency and Goodput Calculator by TheCalcTools
How the Ethernet Frame Efficiency and Goodput Calculator works
Enter the link rate and the payload size (1500 is the standard MTU).
Each frame adds 18 bytes of header and FCS, 8 bytes of preamble and 12 bytes of inter-frame gap, plus any VLAN tag.
Goodput subtracts the IP and TCP headers if you choose to count them.
The formula
Worked example
Using the default values shown in the calculator:
| Link rate (Mbps) | 1000 |
|---|---|
| Ethernet payload (bytes) | 1500 |
| VLAN tag | None |
| Count IP + TCP headers as overhead | Yes, IPv4 + TCP (40 bytes) |
- A 1500-byte payload uses 1,538 bytes on the wire.
- After 40 bytes of IP/TCP headers, efficiency is 94.93% and goodput on 1 Gbps is 949.28 Mbps.
Result:
| Bytes on the wire per frame | 1,538 |
|---|---|
| Efficiency | 94.93% |
| Maximum goodput (Mbps) | 949.28 |
| Frames per second at line rate | 81,274 |
Frequently asked questions
Why is a 1 Gbps link never 1 Gbps of data?
Preamble, gap, headers and FCS use about 5% even with full-size frames; small frames are far worse.
Do jumbo frames help?
A 9000-byte payload lifts efficiency to about 99%, if every device on the path supports it.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.