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OSPF Cost Calculator

Calculate OSPF interface cost based on reference and interface bandwidth

The reference bandwidth used by OSPF to calculate cost. Default is 100 Mbps (auto-cost reference-bandwidth). Modern networks should use 100,000 Mbps or higher to differentiate high-speed links.
The bandwidth of the interface. OSPF cost = Reference BW / Interface BW. Minimum cost is always 1.

OSPF Cost Result

Reference BandwidthMbps
Interface BandwidthMbps
Calculated Cost
Formula

Cost Table for Common Interface Speeds

Interface SpeedBandwidthOSPF Cost
References:
RFC 2328 - OSPF Version 2
Cisco IOS: auto-cost reference-bandwidth command
Formula: Cost = Reference Bandwidth / Interface Bandwidth (minimum 1)