Calculation Results
The estimates combine link, TCP, loss, overhead, and handshake constraints.
Performance Summary
Window, Delay, and Transfer Details
Bottleneck Analysis
Protocol Comparison
| Mode | Estimated Goodput | Setup Delay | Transfer Time | Notes |
|---|
Sensitivity Charts
Calculation Record
Formula Used
The loss equation is a planning model, not a packet-level simulation. Modern congestion controls can behave differently under changing queues and loss. Measured testing remains essential for production network decisions today.
How to Use
- Select a preset or enter link values manually.
- Enter RTT, TCP windows, MSS, and loss.
- Add payload, handshake, and overhead details.
- Choose congestion control and parallel stream count.
- Calculate, review bottlenecks, and export the results.
Example Data
| Scenario | Bandwidth | RTT | Loss | Window | Typical Concern |
|---|---|---|---|---|---|
| Gigabit LAN | 1 Gbit/s | 0.5 ms | 0.001% | 4 MiB | Host processing |
| Fibre broadband | 500 Mbit/s | 15 ms | 0.02% | 4 MiB | Window sizing |
| 4G mobile | 50 Mbit/s | 55 ms | 0.5% | 2 MiB | Loss variability |
| Satellite | 100 Mbit/s | 600 ms | 0.3% | 16 MiB | Large BDP |
Frequently Asked Questions
What is TCP throughput?
TCP throughput is the rate delivered by a TCP connection. It can be lower than physical link bandwidth. Windows, latency, loss, and overhead shape the final result.
How does RTT reduce throughput?
A sender must keep enough unacknowledged data in flight. Higher RTT requires a larger effective TCP window. Small windows can therefore leave fast links underused.
What is the bandwidth-delay product?
The bandwidth-delay product is the data filling the path. It estimates the window required for full utilisation. Parallel streams divide that total requirement across connections.
Why does packet loss matter?
Loss can trigger retransmissions and congestion-window reductions. Its impact grows on high-latency paths. Even small percentages can greatly reduce traditional TCP throughput.
What is the difference between throughput and goodput?
Throughput includes transmitted protocol data. Goodput counts useful application payload delivered successfully. Headers, acknowledgements, encryption, and retransmissions reduce goodput.
Does using parallel streams always help?
Parallel streams can overcome per-flow window or loss limits. They may also increase congestion and unfairness. Use them carefully on shared or constrained networks.
How do MSS and MTU affect performance?
Larger packets reduce header overhead per payload byte. Oversized packets can fragment or fail across paths. The MSS should fit within the selected MTU safely.
Is HTTP/3 a TCP mode?
No, HTTP/3 normally uses QUIC over UDP. It is included only for comparative planning. Its handshake and loss behaviour differ from conventional TCP.
Are these results guaranteed?
No calculator can reproduce every real network condition. Servers, routing, shaping, wireless interference, and operating systems matter. Validate important decisions with controlled throughput measurements.
Planning Disclaimer
These values are engineering estimates for planning and comparison. They do not replace packet captures or controlled performance tests. Validate critical designs under representative production traffic conditions carefully.