TCP Bandwidth-Delay Product (BDP = BW × RTT) & Max Window Throughput Calculator

Calculate TCP Bandwidth-Delay Product (BDP) and maximum single-connection throughput.

Required TCP Window (Bandwidth-Delay Product)
7,934.57 KiB
Max Single-Stream Throughput at Current Window 64.528 Mbps
Default 64 KiB Unscaled Window Cap 8.066 Mbps
Link Utilization Efficiency (%) 6.453 %
Inputs
⚡ Scenarios:
Mbps
Available network link bandwidth in Megabits per second (Mbps).
ms
Round-Trip Time (RTT) network latency in milliseconds.
KiB
Configured OS TCP Receive Window size (RWIN) in KiB (64 KiB unscaled default; 512–4096 KiB tuned).
Results & Graph
Required TCP Window (Bandwidth-Delay Product)
7,934.57 KiB
Max Single-Stream Throughput at Current Window
64.528 Mbps
Default 64 KiB Unscaled Window Cap
8.066 Mbps
Link Utilization Efficiency (%)
6.453 %

Required TCP Window (Bandwidth-Delay Product)

Graph 1 • TCP Bandwidth-Delay Product • Domain Architecture & Live Telemetry Maps Link Bandwidth Mbps, Round Trip Latency Rtt Ms, Configured Tcp Window Ki B through TCP Bandwidth-Delay Product Formula.
Source / Tx Target / Rx TCP Bandwidth-Delay Product Propagation Path Required TCP Window (Bandw 7,934.57 KiB Max Single-Stream Throughp: 64.528 Mbps Default 64 KiB Unscaled Wi: 8.066 Mbps
Graph 2 • Required TCP Window (Bandwidth-Delay Product) Across Link Bandwidth Mbps Sweep (40% → 160%) Evaluates BDP_Bytes = (LinkBandwidth_bps × RTT_seconds) / 8; MaxSingleStream_Mbp across 7 operating points (current input highlighted).
0 KiB 7.0k KiB 14.0k KiB 3.2k 400Mbps 4.8k 600Mbps 6.3k 800Mbps 7.9k 1.0kMbps 9.5k 1.2kMbps 11.1k 1.4kMbps 12.7k 1.6kMbps
Graph 3 • Joint Sensitivity: Link Bandwidth Mbps × Round Trip Latency Rtt Ms Compares Required TCP Window (Bandwidth-Delay Product) when Round Trip Latency Rtt Ms is shifted +25% (solid) vs. −25% (dashed).
0 KiB 7.1k KiB 14.2k KiB --- Round Trip Latency Rtt Ms @ 75% 6.9k -30% 8.4k -15% 9.9k +0% 11.4k +15% 12.9k +30%
Summary: Saturating a 1000 Mbps link across 65 ms RTT requires a TCP Window (BDP) of 7934.6 KiB (7.75 MiB); your 512 KiB window caps single-stream throughput at 64.5 Mbps.
Summary: Saturating a 1000 Mbps link across 65 ms RTT requires a TCP Window (BDP) of 7934.6 KiB (7.75 MiB); your 512 KiB window caps single-stream throughput at 64.5 Mbps.
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Formula & Mathematical Methodology: TCP Bandwidth-Delay Product Formula

BDPBytes = (LinkBandwidthbps × RTTseconds) / 8
MaxSingleStreamMbps = (TcpWindowBytes × 8) / RTTseconds / 10⁶
BDP_Bytes = (LinkBandwidth_bps × RTT_seconds) / 8; MaxSingleStream_Mbps = (TcpWindowBytes × 8) / RTT_seconds / 10⁶
  • linkBandwidthMbps: Available network link bandwidth in Megabits per second (Mbps).
  • roundTripLatencyRttMs: Round-Trip Time (RTT) network latency in milliseconds.
  • configuredTcpWindowKiB: Configured OS TCP Receive Window size (RWIN) in KiB (64 KiB unscaled default; 512–4096 KiB tuned).

Rounding: Internal floating-point calculations run in 64-bit IEEE-754 double precision; display values round to 2–4 decimal places.

Worked Example: TCP Bandwidth-Delay Product Worked Example

Calculate TCP Bandwidth-Delay Product (BDP) and maximum single-connection throughput.

  1. Enter the input measurement, system configuration, or astronomical parameter.
  2. Apply the standard conversion or analytical equation: BDP_Bytes = (LinkBandwidth_bps × RTT_seconds) / 8; MaxSingleStream_Mbps = (TcpWindowBytes × 8) / RTT_seconds / 10⁶.
  3. Inspect the primary metric, secondary equivalents, and 3 real-time SVG graphs.
Result: Computes TCP Bandwidth-Delay Product via BDP_Bytes = (LinkBandwidth_bps × RTT_seconds) / 8; MaxSingleStream_Mbps = (TcpWindowBytes × 8) / RTT_seconds / 10⁶.

Frequently Asked Questions

How does the TCP Bandwidth-Delay Product (BDP = BW × RTT) & Max Window Throughput Calculator perform the calculation?

It evaluates BDP_Bytes = (LinkBandwidth_bps × RTT_seconds) / 8; MaxSingleStream_Mbps = (TcpWindowBytes × 8) / RTT_seconds / 10⁶ directly in your browser and renders three custom SVG charts in real time.

Can I solve backwards for an input parameter using Goal Seek?

Yes. Click "🎯 Goal Seek" in the results toolbar to solve backwards for any numeric input field.

Does this tool work offline?

Yes. All calculations run 100% locally in your browser with full offline PWA support.

Developer Tools · Networking & Systems Performance

TCP Bandwidth-Delay Product (BDP = BW × RTT) & Max Window Throughput Calculator: inputs, method, and how to read the result

Calculate TCP Bandwidth-Delay Product (BDP) and maximum single-connection throughput.

Choose inputs for the case you are checking

The defaults are illustrative. Replace them with values for your case and keep the units shown beside each field.

  • Link Bandwidth Mbps: Available network link bandwidth in Megabits per second (Mbps).
  • Round Trip Latency Rtt Ms: Round-Trip Time (RTT) network latency in milliseconds.
  • Configured Tcp Window Ki B: Configured OS TCP Receive Window size (RWIN) in KiB (64 KiB unscaled default; 512–4096 KiB tuned).

What the calculation includes

With the default values shown, Required TCP Window (Bandwidth-Delay Product) is 7,934.57 KiB. The calculation follows TCP Bandwidth-Delay Product Formula; the formula and variable definitions above show how the inputs combine.

One-input check: With the other defaults held constant, changing Link Bandwidth Mbps from 1,000 Mbps to 1,100 Mbps changes Required TCP Window (Bandwidth-Delay Product) from 7,934.57 KiB to 8,728.027 KiB. This is a comparison inside the calculator's stated model, not a prediction.

Where to use caution

  • Uses official NIST Special Publication 811, IEEE/RFC systems engineering, APA psychometric, and USNO astronomical formulas.
  • Empirical metallurgy and calendar conversions represent standard reference-condition approximations.

Scope: Global NIST, IEEE, APA & Astronomical Standard Check the assumptions and limitations against your situation before relying on the estimate.

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