MTU Test: Check Packet Size

Find the Maximum Transmission Unit for your network. Prevent packet fragmentation and optimize your speed for VPN and Gaming.

AI Overview

An MTU test identifies the largest data packet your connection can handle. The standard size is 1500 bytes. If packets are too large, they fragment, causing high ping and slow loading. Testing ensures your MSS (Maximum Segment Size) is correctly tuned for your ISP or VPN tunnel.

Detects MTU, MSS, and fragmentation status instantly.

What is an MTU Test?

The Maximum Transmission Unit (MTU) is the largest packet size that can be sent over a network connection. Think of it as a height limit for a tunnel; if your data "truck" is too tall, it has to be broken down into smaller pieces. This process is called fragmentation, and it significantly slows down your internet speed.

Quick Tip: If your VPN keeps disconnecting or websites load halfway, your MTU is likely set too high. Dropping it to 1400 often fixes the issue immediately.

How to Find Your Optimal MTU Size

You can check your MTU manually on Windows using the Command Prompt. Follow these steps:

ping -f -l 1472 8.8.8.8

If you see "Packet needs to be fragmented," lower the number 1472 by 10 and try again. Once it passes, add 28 to that number to find your true MTU.

MTU for Gaming and VPN

  • Gaming: Use an MTU of 1500 for wired and 1472 for Wi-Fi to reduce lag spikes.
  • VPN: Most VPNs (WireGuard/OpenVPN) require an MTU between 1380 and 1420 due to encryption overhead.
  • PPPoE (DSL/Fiber): Usually requires an MTU of 1492.

Frequently Asked Questions

Does MTU affect speed?
Yes. Incorrect MTU causes your router to work harder to split packets, increasing latency and lowering throughput.

What is MSS?
Maximum Segment Size (MSS) is the actual data part of the packet. It is always 40 bytes smaller than the MTU (MTU - 40 = MSS).

Can I set MTU to 9000?
Only on local networks (Jumbo Frames). The public internet only supports a maximum of 1500.