Network Tools

MTU Test — Maximum Transmission Unit Calculator

Calculate MTU payloads and check host reachability

Common MTU presets:

How to Use This Tool

  1. Enter MTU bytes (default 1500) or pick a preset.
  2. Optionally enter a hostname to test HTTP reachability.
  3. Review max TCP and UDP payload sizes.
  4. Adjust MTU for PPPoE (1492) or VPN tunnels if needed.

About This Tool

Maximum Transmission Unit (MTU) defines the largest IP packet on a link. Wrong MTU causes fragmentation, VPN drops, and slow transfers. Use this tool to compute TCP/UDP payload sizes from your MTU and verify a host responds over HTTPS.

Common use cases

  • Pick MTU for VPN or PPPoE without fragmentation
  • Calculate max TCP payload from interface MTU

Common MTU values

Ethernet uses 1500 bytes. PPPoE often uses 1492. WireGuard tunnels frequently use 1420 on a 1500 underlying link.

Frequently Asked Questions

Yes. VSPIC offers this MTU test at no cost with no account required. Results load in real time.

We do not permanently store your queries on our servers. Some tools run entirely in your browser; others fetch public data for the request only.

Yes. Open the page in any modern phone or tablet browser. Results work on Wi‑Fi and mobile data.

PMTU finds the smallest MTU along the route using ICMP. Browser-based tools cannot run full ICMP PMTU; lower MTU manually when you see VPN or PPPoE issues.

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