Private browser-based analyzer
iperf3 Result Analyzer
Paste iperf3 JSON or terminal output to compare sender and receiver throughput, retransmits, packet loss and nominal-link efficiency.
Prefer JSON when you can
Run iperf3 -c SERVER_IP --json for machine-readable TCP output. Repeat with -R because upload and download paths can behave differently. For multi-gigabit testing, parallel streams such as -P 4 can reveal whether one TCP stream is the limiting factor.
How to read efficiency
Efficiency is receiver throughput divided by the nominal link rate. A healthy 1GbE large-stream TCP test often lands around 90–94%, but that is a diagnostic starting point rather than a universal pass mark. Wi-Fi, WAN latency, encryption, CPU limits, small buffers and retransmissions can reduce it.
iperf3 measures the network path, not SMB/NFS file-copy speed. Storage, filesystem metadata, signing and antivirus can make application transfers slower.
Use repeatable tests
- Use the same server, cable, switch port, duration and stream count.
- Record both directions and at least three runs.
- For UDP, choose a target bitrate deliberately and inspect packet loss and jitter.
- Save raw output; a screenshot alone can hide command options.
Our EQi12 network report combines controller identity, link behavior and SMB copies; use this analyzer for standardized iperf3 evidence alongside those application tests.