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Network Engineer

MTU and Payload Calculator

Use this mtu and payload calculator entirely in your browser.

ResultMaximum payload: 1,460 bytes

Header share: 2.66666666667%.

Payload efficiency: 97.3333333333%.

Calculations happen locally in your browser.

How to use this calculator

  1. Enter the labelled values and review the live result.
  2. Review the live result and use Copy result when you need to share it.

How the calculation works

Maximum payload equals MTU minus the entered IP and transport headers.

Formula

Maximum payload equals MTU minus the entered IP and transport headers.

Step-by-step calculation

  1. Enter the labelled values and review the live result.
  2. Maximum payload equals MTU minus the entered IP and transport headers.
  3. Check the displayed result, then copy it if needed.

Worked example

A 1,500-byte MTU with 20-byte IPv4 and TCP headers carries a 1,460-byte payload.

Methodology and review

Who this is for

Engineers comparing packet payload and header overhead.

Inputs and units

  • MTU
  • IP and transport header sizes
  • Optional extra headers

Method

Configured protocol-header bytes are subtracted from MTU to show payload per packet; payload divided by frame size estimates efficiency.

Worked example

A 1500-byte MTU with 20-byte IPv4 and TCP headers leaves 1460 bytes of payload.

Assumptions

  • Header sizes entered match the intended protocol stack.
  • No additional tunnel or link-layer headers are omitted.

Common mistakes

  • Omitting tunnel headers
  • Confusing MTU with full Ethernet frame size

Limitations

  • Options, VLANs, VPNs, encapsulation, and hardware offload change observed frames.
  • Path MTU must be measured or obtained from the network design.

How this tool was checked

Tests cover standard Ethernet/IP combinations, custom headers, and rejection of headers larger than MTU.

Reference sources

Related tools

Calculation review: 21 August 2026. Published by Goldwave Dynamics Limited. This is an internal product review, not an independent certification.

Risk guidance

Frequently asked questions

Does this tool send my inputs anywhere?

No. The interactive calculation runs in your browser and this site does not submit tool inputs to a backend.

How should I use the result?

Check that the entered units and values match your situation, especially around dates, breaks, and rounding.

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