MTU Test — Maximum Transmission Unit Calculator
Calculate MTU payloads and check host reachability
How to Use This Tool
- Enter MTU bytes (default 1500) or pick a preset.
- Optionally enter a hostname to test HTTP reachability.
- Review max TCP and UDP payload sizes.
- 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.
Need your public IP first?
Instantly see IPv4, IPv6, ISP, city, and map before other network tests.
Related Tools
Explore more free VSPIC tools for IP, DNS, security, and network diagnostics.
Speed Test
Measure download, upload, ping, and jitter for your connection
Use Free →Ping Test
Measure latency to any hostname or IP address
Use Free →Port Checker
Test if common ports are open on a host
Use Free →HTTP Status Checker
Check HTTP response codes, latency, and headers for any URL
Use Free →Website Down Checker
See if a website is up or down with multi-probe checks
Use Free →Port Scanner
Scan common ports (21, 22, 80, 443, 3389…) on any host
Use Free →
Trusted by Users Who Value Privacy
Always Free
No premium plan ever
100% Private
Files processed in browser
Instant Results
Convert in seconds
Works Everywhere
Any device, any OS