Check and calculate your network MTU online. Test common MTU values, identify possible packet-size problems, and find the recommended MTU for your internet connection.
Check common MTU values and calculate the corresponding IPv4 ping payload size.
An MTU test helps you understand the Maximum Transmission Unit used by a network connection. MTU is the largest packet size that can normally be transmitted over a network link without requiring fragmentation. A standard Ethernet network commonly uses an MTU of 1500 bytes, while some PPPoE, VPN, tunnel and other connections can use a lower value.
Use this free MTU Test to check common MTU values, understand packet-size compatibility and troubleshoot problems that may be related to an incorrect MTU configuration.
MTU stands for Maximum Transmission Unit. It represents the maximum size of an IP packet that can be transmitted over a network interface or path without fragmentation.
For many Ethernet connections, 1500 bytes is the standard MTU. PPPoE connections commonly use 1492 bytes because of protocol overhead. VPNs and tunnels can reduce the usable packet size even further.
An incorrect MTU can sometimes cause unusual network problems. Small websites or simple connections may work normally while larger transfers, VPN connections, secure connections or specific applications experience delays or failures.
| Connection Type | Common MTU |
|---|---|
| Standard Ethernet | 1500 |
| PPPoE | 1492 |
| Some VPN connections | Lower than 1500 |
| Jumbo Frames | Usually around 9000 |
This browser tool provides a practical MTU diagnostic and calculator. It compares common MTU values, calculates the corresponding IPv4 ping payload size and explains what each result means.
For an actual path-MTU measurement, packet-level testing must be performed by a system that can send packets with fragmentation control. Browsers do not expose raw ICMP or packet-fragmentation controls directly.
For an IPv4 ICMP ping test, the commonly used calculation is:
MTU = ICMP payload + 28 bytes
The additional 28 bytes represent the IPv4 header and ICMP header. For example, an MTU of 1500 corresponds to an ICMP payload of 1472 bytes.
If your internet connection works for basic browsing but certain websites, VPN services, file transfers or applications fail, MTU can be one possible cause. However, MTU is only one part of network troubleshooting. DNS, packet loss, routing, firewall rules and server-side problems can produce similar symptoms.
VPN tunnels and PPPoE connections may introduce additional overhead. This can reduce the effective packet size available to applications. If you are troubleshooting a VPN or PPPoE connection, compare the configured MTU with the MTU supported by the complete network path.
Use the MTU Test above to understand common MTU values and calculate the corresponding packet payload size.
MTU means Maximum Transmission Unit. It is the maximum packet size that can normally be transmitted over a network link without fragmentation.
1500 bytes is the common MTU for standard Ethernet networks.
PPPoE commonly uses an MTU of 1492 bytes because of protocol overhead.
The test can help identify possible packet-size problems, but changing MTU settings should only be done when testing confirms that an MTU mismatch is involved.
No. Normal browser JavaScript cannot directly send raw ICMP packets with fragmentation control. A true Path MTU measurement requires packet-level testing outside normal browser APIs.
1500 bytes is the common Ethernet MTU, but the correct value depends on your network, ISP, VPN, tunnel and equipment.
Some VPN and tunnel configurations reduce the usable packet size because additional headers require extra space.
For IPv4 ICMP testing, an MTU of 1500 corresponds to a commonly used ping payload of 1472 bytes.
Yes. The tool is designed to be free to use online.
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