Protocol Overhead Calculator

Work out protocol overhead instantly with clear inputs, formula shown and shareable results.

About Protocol Overhead Calculator

Every frame carries an Ethernet header and trailer, preamble and inter-frame gap totalling 38 bytes, plus IP and transport headers. With a 1460-byte payload that is about 95 percent efficiency, but small packets are far worse — a 20-byte voice payload spends more than three quarters of the wire on headers, which is why voice bandwidth per call is many times its codec rate.

Formula

Protocol efficiency

headers = 38 Ethernet + IP header + transport header (+ RTP); efficiency = payload / (payload + headers); wire rate = goodput / efficiency

Worked example

With the default values below, Protocol Overhead Calculator returns Wire rate required of 105.34. Change any input above and every figure here is recalculated in your browser.

Inputs used

Application payload per packetaccepts 1–65,000 bytes: 1,460 bytes
Protocol stackone of Ethernet + IPv4 + TCP, Ethernet + IPv4 + UDP, Ethernet + IPv6 + TCP, Ethernet + IPv4 + UDP + RTP (voice): Ethernet + IPv4 + TCP
Application goodput requiredminimum 0.001 Mbps: 100 Mbps

Results

Wire rate required: 105.34 Mbps
Header and framing bytes: 78 bytes
Protocol efficiency: 94.93%
Bandwidth consumed by overhead: 5.34 Mbps

Step by step

1Values used
2Protocol efficiency
3Wire rate required= 105.34 Mbps
4Header and framing bytes= 78 bytes
5Protocol efficiency= 94.93
6Bandwidth consumed by overhead= 5.34 Mbps

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why include the preamble and inter-frame gap?

Because they occupy time on the wire even though they are not part of the frame. Ignoring them understates the required link rate by about 1.3 percent at full-size frames and far more at small ones.

Do jumbo frames help much?

At 9000 bytes efficiency rises above 99 percent and per-packet CPU cost falls sharply. The catch is that every device in the path must agree on the larger MTU.