calc.engineer / Homelab & Networking / TCP Throughput

TCP Throughput v1.0.0

Calculate maximum TCP throughput using the Bandwidth-Delay Product (BDP) formula. Given link bandwidth and round-trip latency, computes the BDP (maximum in-flight data), achievable throughput with a given TCP window size, link utilization percentage, and recommended window size for full utilization. Critical for diagnosing slow transfers over high-latency links (WAN, VPN, satellite), tuning TCP buffers, and understanding why a 1Gbps link may only deliver 25Mbps with default 64KB windows. Applies to iperf testing, WAN optimization, and network capacity planning.

feeds wireguard_mtu →
Available link bandwidth in megabits per second
Round-trip time (latency) in milliseconds
TCP receive window size in kilobytes
Maximum Segment Size in bytes (typically 1460 for Ethernet)
Fill in the inputs and Compute to see the structured result.

From an agent (MCP) or the API

curl -X POST https://calc.engineer/api/tcp_throughput \
  -H "Content-Type: application/json" \
  -d '{"bandwidth_mbps": …, "rtt_ms": …, "window_size_kb": …}'

MCP: connect to https://calc.engineer/mcp and call tcp_throughput.

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