Free tool · Routing & Aggregation

OSPF Cost Calculator

Turn any interface bandwidth into its OSPF cost.

OSPF cost1
Presets

Cisco OSPF cost = reference bandwidth / interface bandwidth, truncated, minimum 1. With the default 100 Mbps reference every link at or above 100 Mbps gets cost 1, so raise it (auto-cost reference-bandwidth 100000 for 100G) and set it identically on every router in the area.

About this tool

Free OSPF cost calculator. Enter an interface bandwidth and reference bandwidth to get the Cisco OSPF cost (reference bandwidth divided by interface bandwidth, minimum 1), with presets for common link speeds and the auto-cost reference-bandwidth value to set. Everything runs entirely in your browser — nothing you type is sent to a server.

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