Raspberry Pi 4 Maximum Gigabit Ethernet Throughput

The Raspberry Pi 4 features a significant networking upgrade over its predecessors by introducing a full, non-throttled onboard Gigabit Ethernet port. This article provides an overview of the maximum real-world data throughput achievable on the Raspberry Pi 4’s native Ethernet port, explaining the differences between theoretical limits and real-world benchmarking results using standard testing tools like iperf3.

Unlike previous models like the Raspberry Pi 3 B+, which capped networking speeds at roughly 300 Mbps because the Ethernet controller was bottlenecked by an internal USB 2.0 bus, the Raspberry Pi 4 connects its Gigabit Ethernet PHY directly to the Broadcom BCM2711 SoC via a dedicated RGMII interface. This architectural shift completely unlocks the interface, allowing the mini-computer to utilize the full capability of a 1 Gbps network connection.

In ideal testing environments using the popular network benchmarking tool iperf3, the Raspberry Pi 4 achieves a maximum sustained throughput of 940 Mbps to 943 Mbps for standard TCP traffic. For UDP traffic, which carries less protocol overhead than TCP, the throughput can slightly edge higher to around 950 Mbps to 958 Mbps.

It is mathematically impossible to hit a flat 1,000 Mbps (1 Gbps) on any standard Gigabit Ethernet device due to mandatory network protocol overheads. Every packet transmitted requires space for physical layer framing, IP headers, and TCP/UDP headers. Because of this, a real-world score of ~940 Mbps represents the absolute maximum theoretical limit of a Gigabit line, proving that the Raspberry Pi 4 hardware can fully saturate a Gigabit link without any internal hardware bottlenecks.

Achieving this maximum throughput depends on a clean networking environment. Real-world performance requires using high-quality Cat5e or Cat6 Ethernet cabling and ensuring the Pi is connected to a true Gigabit switch or router port. Furthermore, processing raw 1 Gbps data streams is a CPU-intensive task for a single-board computer; during maximum throughput tests, it is common to see one or two CPU cores on the Raspberry Pi 4 reach near 100% utilization to handle the heavy network interrupts.