VPN Tunnel (WireGuard / IPSec / VXLAN) MTU, TCP MSS & Goodput Calculator

Compute fragmentation-free WireGuard/IPSec MTU and TCP MSS clamping values.

Optimal Tunnel Interface MTU
1,440 bytes
Clamped TCP MSS (MTU − Headers) 1,400 bytes
Protocol Goodput Efficiency 93.33 %
Total Encapsulation + TCP/IP Overhead 100 bytes
Inputs
bytes
Underlying WAN interface MTU in bytes (1500 Ethernet, 1492 PPPoE).
bytes
Tunnel header overhead in bytes (60 WireGuard IPv4, 80 WireGuard IPv6, 73 IPSec).
bytes
Inner IP + TCP header bytes (40 for IPv4, 60 for IPv6).
Results & Graph
Optimal Tunnel Interface MTU
1,440 bytes
Clamped TCP MSS (MTU − Headers)
1,400 bytes
Protocol Goodput Efficiency
93.33 %
Total Encapsulation + TCP/IP Overhead
100 bytes

Optimal Tunnel Interface MTU

Graph 1 • Physical Wan Mtu Bytes Sensitivity Recalculates the domain equation across 50% to 150% of the primary input while holding other parameters constant.
0 bytes 1.2k bytes 2.4k bytes 50%: 690 bytes 690 50% 75%: 1,065 bytes 1.1k 75% 100%: 1,440 bytes 1.4k 100% 125%: 1,815 bytes 1.8k 125% 150%: 2,190 bytes 2.2k 150%
Graph 2 • Primary & Supporting Metric Comparison Compares the primary output alongside supporting domain benchmarks.
Optimal Tunnel Interface MTU 1,440 bytes Clamped TCP MSS (MTU − Headers) 1,400 bytes Protocol Goodput Efficiency 93.33 % Total Encapsulation + TCP/IP Overhead 100 bytes
Graph 3 • Exact Output Table & Units Displays each calculated output in its exact domain unit.
Optimal Tunnel Interface MTU1,440 bytesClamped TCP MSS (MTU − Headers)1,400 bytesProtocol Goodput Efficiency93.33 %Total Encapsulation + TCP/IP Overhead100 bytes
Summary: Subtracting 60 B tunnel overhead from 1500 B WAN MTU gives a fragmentation-free Tunnel MTU of 1440 bytes and TCP MSS of 1400 bytes (93.3% payload efficiency).
Summary: Subtracting 60 B tunnel overhead from 1500 B WAN MTU gives a fragmentation-free Tunnel MTU of 1440 bytes and TCP MSS of 1400 bytes (93.3% payload efficiency).
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Interactive chart & math engine powered by CalculatorGraph

Formula & Mathematical Methodology: VPN MTU & TCP MSS Systems Engineering Formula

TunnelMTU = PhysicalMTU − EncapsulationOverhead
TCPMSS = TunnelMTU − 40 (IPv4) or − 60 (IPv6)
Tunnel_MTU = Physical_MTU − EncapsulationOverhead; TCP_MSS = Tunnel_MTU − 40 (IPv4) or − 60 (IPv6)
  • physicalWanMtuBytes: Physical Wan Mtu Bytes (bytes)
  • tunnelEncapsulationOverheadBytes: Tunnel Encapsulation Overhead Bytes (bytes)
  • tcpIpHeaderBytes: Tcp Ip Header Bytes (bytes)

Rounding: Binary/decimal capacities and engineering metrics retain full floating-point precision and round to 2 decimal places.

Worked Example: Architecture Sizing Example: VPN MTU & TCP MSS

Compute fragmentation-free WireGuard/IPSec MTU and TCP MSS clamping values.

  1. Enter the workload parameters, model dimensions, or network link specifications.
  2. Compute the sizing equation: Tunnel_MTU = Physical_MTU − EncapsulationOverhead; TCP_MSS = Tunnel_MTU − 40 (IPv4) or − 60 (IPv6).
  3. Inspect the primary capacity metric, headroom buffers, and 3 SVG visualizations.
Result: Calculates VPN MTU & TCP MSS via Tunnel_MTU = Physical_MTU − EncapsulationOverhead; TCP_MSS = Tunnel_MTU − 40 (IPv4) or − 60 (IPv6).

Frequently Asked Questions

How does the VPN Tunnel (WireGuard / IPSec / VXLAN) MTU, TCP MSS & Goodput Calculator compute capacity?

It evaluates Tunnel_MTU = Physical_MTU − EncapsulationOverhead; TCP_MSS = Tunnel_MTU − 40 (IPv4) or − 60 (IPv6) directly in your browser and plots three custom SVG diagrams.

Can I compare different cluster or model configurations side by side?

Yes. Use the "Compare (0/3)" button in the results panel to pin up to three configurations.

Does this tool upload any of my architecture parameters?

No. All calculations run 100% client-side in your browser.

Developer Tools · Networking & Digital Systems

VPN Tunnel (WireGuard / IPSec / VXLAN) MTU, TCP MSS & Goodput Calculator: inputs, method, and how to read the result

Compute fragmentation-free WireGuard/IPSec MTU and TCP MSS clamping values.

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.

  • Physical Wan Mtu Bytes: Underlying WAN interface MTU in bytes (1500 Ethernet, 1492 PPPoE).
  • Tunnel Encapsulation Overhead Bytes: Tunnel header overhead in bytes (60 WireGuard IPv4, 80 WireGuard IPv6, 73 IPSec).
  • Tcp Ip Header Bytes: Inner IP + TCP header bytes (40 for IPv4, 60 for IPv6).

What the calculation includes

With the default values shown, Optimal Tunnel Interface MTU is 1,440 bytes. The calculation follows VPN MTU & TCP MSS Systems Engineering Formula; the formula and variable definitions above show how the inputs combine.

One-input check: With the other defaults held constant, changing Physical Wan Mtu Bytes from 1,500 bytes to 1,650 bytes changes Optimal Tunnel Interface MTU from 1,440 bytes to 1,590 bytes. This is a comparison inside the calculator's stated model, not a prediction.

Where to use caution

  • Uses industry-standard IEEE, IETF RFC, and GPU/cloud hardware sizing conventions.
  • Capacity planning estimate; benchmark under production traffic patterns before finalizing cluster or hardware procurement.

Scope: IEEE / IETF / Cloud Systems Engineering Standard Check the assumptions and limitations against your situation before relying on the estimate.

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