homelab

Calculate the optimal MTU for a WireGuard VPN tunnel interface with a detailed overhead breakdown. Accounts for WireGuard header (32 bytes), outer IP header (20 bytes IPv4 or 40 bytes IPv6), UDP header (8 bytes), and optional PPPoE encapsulation (8 bytes). Prevents fragmentation and PMTUD black holes by computing the maximum inner packet size that fits within the physical link MTU. Essential for WireGuard setup on residential ISP connections (PPPoE), IPv6 tunnels, and any VPN where incorrect MTU causes slow or stalled connections.

post/api/wireguard_mtu

Request

  • Base URL: https://calc.engineer
  • URL: https://calc.engineer/api/wireguard_mtu
  • Auth: none declared

Request body

interface_mtunumber

MTU of the underlying physical or virtual network interface in bytes

ipv6boolean

Whether the outer (transport) IP header uses IPv6 (40 bytes) instead of IPv4 (20 bytes)

over_pppoeboolean

Whether the link uses PPPoE encapsulation (adds 8 bytes of overhead)

Response

Computed result for wireguard_mtu

toolstring required
versionstring required
computed_atstring date-time required

Changes

No recorded changes to this operation across all 1 revision of this API.