Calculator Inputs
The page remains single-column overall, while the input grid becomes three columns on large screens, two on medium screens, and one on mobile.
Plotly Graph
This graph compares effective payload throughput and payload efficiency across common frame payload sizes using your current overhead and utilization inputs.
Example Data Table
These examples assume Ethernet header 14 bytes, IPv4 header 20 bytes, TCP header 20 bytes, FCS 4 bytes, preamble 8 bytes, interframe gap 12 bytes, and 95% utilization.
| Scenario | Line Rate | Payload Bytes | On-Wire Bytes | Efficiency | Effective Goodput | 10 GB Transfer Time |
|---|---|---|---|---|---|---|
| Fast Ethernet, standard payload | 100 Mbps | 1,460 | 1,538 | 94.93% | 90.18 Mbps | 15 minutes, 52.51 seconds |
| Gigabit Ethernet, standard payload | 1 Gbps | 1,460 | 1,538 | 94.93% | 901.82 Mbps | 1 minute, 35.25 seconds |
| Gigabit Ethernet, jumbo payload | 1 Gbps | 9,000 | 9,078 | 99.14% | 941.84 Mbps | 1 minute, 31.20 seconds |
| 10 Gigabit Ethernet, standard payload | 10 Gbps | 1,460 | 1,538 | 94.93% | 9,018.21 Mbps | 9.53 seconds |
Formula Used
Raw Line Rate = Configured Rate × Unit Multiplier
On-Wire Bytes = Payload + Ethernet Header + VLAN + Network Header + Transport Header + FCS + Miscellaneous Bytes + Preamble + Interframe Gap
Packets Per Second = Raw Line Rate ÷ (On-Wire Bytes × 8)
Effective PPS = Theoretical PPS × (Utilization ÷ 100)
Effective Payload Throughput = Effective PPS × Payload Bytes × 8
Payload Efficiency % = (Payload Bytes ÷ On-Wire Bytes) × 100
Transfer Time = Data Size In Bits ÷ Effective Payload Throughput
This approach distinguishes between raw link capacity and usable payload delivery. It accounts for framing, headers, preamble, and interframe gap, which is why usable throughput is always lower than nominal Ethernet speed.
How To Use This Calculator
- Enter the Ethernet line rate and choose the matching rate unit.
- Enter payload bytes carried in each frame.
- Adjust Ethernet, VLAN, network, transport, and extra overhead bytes.
- Set preamble and interframe gap values if your model requires them.
- Choose expected utilization to reflect protocol behavior, traffic bursts, or contention.
- Enter a data size if you want transfer-time estimation.
- Submit the form to show results above the calculator.
- Use the CSV and PDF buttons to export the result summary.
FAQs
1. What does this Ethernet speed calculator estimate?
It estimates raw line rate, effective payload throughput, payload efficiency, packets per second, overhead ratio, and transfer time. It is useful for comparing standard and jumbo payload behavior under realistic framing and utilization assumptions.
2. Why is payload throughput lower than line rate?
Ethernet spends bandwidth on headers, frame check sequence, preamble, and interframe gap. Real traffic also has protocol inefficiencies and utilization limits. Because of that, usable payload delivery always falls below the advertised physical link rate.
3. What are on-wire bytes?
On-wire bytes are the total bytes consumed for each transmitted frame across the medium. They include payload plus protocol overhead and physical overhead such as preamble and interframe gap, which directly affect packets per second and goodput.
4. Should I include VLAN bytes?
Yes, when VLAN tagging is present. A standard single VLAN tag typically adds four bytes. QinQ or stacked tagging adds more. Including those bytes gives a more realistic estimate of true Ethernet payload efficiency.
5. How does utilization affect the answer?
Utilization scales the theoretical maximum down to a more practical value. It helps model real traffic, queueing, burstiness, pauses, and protocol behavior. A lower utilization produces lower effective packets per second and lower payload throughput.
6. Does duplex mode matter here?
Yes. Per-direction payload throughput stays the same, but full duplex doubles the aggregate simultaneous send-and-receive payload capacity. Half duplex keeps aggregate throughput equal to one direction and can experience contention in shared environments.
7. Are jumbo frames always better?
Not always, but they usually improve efficiency by reducing overhead per payload byte. Their benefit depends on end-to-end support, latency requirements, workload type, switch settings, and whether every device in the path accepts the larger frame size.
8. Can I use this for TCP, UDP, or custom traffic models?
Yes. Enter the appropriate network and transport header sizes for your traffic profile. That allows the calculator to approximate TCP, UDP, IPv4, IPv6, tunneling, or custom encapsulation overhead with the same core Ethernet framing logic.