Standard TCP/IPv4 over Ethernet usually has ~54 bytes of headers.
Effective Data Rate: Mbps
Efficiency:
Transfer Time (1 GB file):
Total Overhead per Packet:
function calculateThroughput() {
// 1. Get input values
var linkSpeed = parseFloat(document.getElementById("linkSpeed").value);
var payloadSize = parseFloat(document.getElementById("payloadSize").value);
var protocolOverhead = parseFloat(document.getElementById("protocolOverhead").value);
var hardwareGap = parseFloat(document.getElementById("hardwareGap").value);
var packetLoss = parseFloat(document.getElementById("packetLoss").value);
// 2. Validation
if (isNaN(linkSpeed) || linkSpeed <= 0) {
alert("Please enter a valid Nominal Link Speed greater than 0.");
return;
}
if (isNaN(payloadSize) || payloadSize <= 0) {
alert("Please enter a valid Payload Size.");
return;
}
if (isNaN(protocolOverhead) || protocolOverhead < 0) {
protocolOverhead = 0;
}
if (isNaN(hardwareGap) || hardwareGap < 0) {
hardwareGap = 0;
}
if (isNaN(packetLoss) || packetLoss < 0) {
packetLoss = 0;
}
// 3. Logic for Effective Data Rate (Goodput)
// Total size occupied on the wire per packet (in Bytes)
// Packet = Payload + Headers + InterFrameGap/Preamble
var totalPacketSizeOnWire = payloadSize + protocolOverhead + hardwareGap;
// Calculate Efficiency Ratio (Percentage of wire usage that is actual data)
// Efficiency = Useful Data / Total Size Occupied
var rawEfficiency = payloadSize / totalPacketSizeOnWire;
// Apply Packet Loss Factor
// If 1% loss, throughput is 99% of the efficient rate (simplified model)
var lossFactor = (100 – packetLoss) / 100;
// Effective Rate formula:
// Nominal Speed * (Payload / TotalSize) * LossFactor
var effectiveRate = linkSpeed * rawEfficiency * lossFactor;
// Calculate Transfer Time for a 1 GB (Gigabyte) file
// 1 GB = 1024 * 1024 * 1024 * 8 bits = 8,589,934,592 bits
// Time = Total Bits / (Effective Rate in bps)
var bitsIn1GB = 8589934592;
var effectiveRateBps = effectiveRate * 1000000;
var transferTimeSeconds = bitsIn1GB / effectiveRateBps;
// Formatting Time
var timeString = "";
if (transferTimeSeconds < 60) {
timeString = transferTimeSeconds.toFixed(2) + " seconds";
} else if (transferTimeSeconds < 3600) {
var mins = Math.floor(transferTimeSeconds / 60);
var secs = (transferTimeSeconds % 60).toFixed(0);
timeString = mins + " min " + secs + " sec";
} else {
var hours = Math.floor(transferTimeSeconds / 3600);
var remaining = transferTimeSeconds % 3600;
var mins = Math.floor(remaining / 60);
timeString = hours + " hr " + mins + " min";
}
// 4. Update UI
document.getElementById("resEffectiveRate").innerHTML = effectiveRate.toFixed(2);
document.getElementById("resEfficiency").innerHTML = (rawEfficiency * 100).toFixed(2) + "%";
document.getElementById("resTransferTime").innerHTML = timeString;
document.getElementById("resTotalOverhead").innerHTML = (protocolOverhead + hardwareGap) + " Bytes";
document.getElementById("resultOutput").style.display = "block";
}
Understanding Effective Data Rate
In networking, the nominal bandwidth (often advertised as "link speed") rarely matches the actual speed at which you can transfer useful files or data. This discrepancy is due to overheads introduced by network protocols and physical hardware limitations. This Effective Data Rate Calculator helps network engineers and developers estimate the actual "Goodput"—the application-level throughput—based on protocol efficiency and line conditions.
Why is "Throughput" Lower than "Bandwidth"?
When you send data over a network, it is encapsulated in various layers. Each layer adds its own "header" (and sometimes a footer/trailer) containing control information. This means a significant portion of the bandwidth is consumed by data that isn't your actual file payload.
Layer
Typical Overhead
Description
Physical (Ethernet)
20 Bytes
Preamble (8 bytes) + Inter-Frame Gap (12 bytes equivalent).
Data Link (Ethernet Frame)
18 Bytes
MAC addresses, Type, FCS (CRC checksum).
Network (IP)
20 Bytes
Source/Dest IP, TTL, Protocol. (IPv4 default).
Transport (TCP)
20 Bytes
Ports, Seq numbers, Flags.
How to Calculate Effective Data Rate
The calculation determines the ratio of "payload" (your actual data) to the total size of the frame on the wire. The formula used in this calculator is:
Once the efficiency percentage is determined, it is multiplied by the nominal link speed. If packet loss occurs, the rate is further reduced because lost packets must be retransmitted (in TCP) or are simply missing (in UDP), lowering the effective throughput.
Example Calculation
Imagine a standard 1000 Mbps (1 Gbps) Ethernet link using TCP/IP.
This explains why you never see a full 1000 Mbps file transfer speed on a Gigabit connection; the maximum theoretical limit is roughly 940-950 Mbps due to unavoidable overheads.
Factors Affecting Data Rate
MTU (Maximum Transmission Unit): Larger MTU sizes (like Jumbo Frames at 9000 bytes) increase the ratio of payload to overhead, improving efficiency.
Packet Loss: Wireless networks or congested links cause packet loss. In TCP, this triggers "back-off" algorithms that drastically reduce speed to prevent congestion.
Protocol Selection: UDP has lower overhead (8 byte header) compared to TCP (20 byte header), but lacks reliability features.