Use Table Rates with a FPUD (fixed per unit of distance) calculation: the configured amount is multiplied by the measured delivery distance. Keep delivery eligibility separate from price calculation, define the valid distance range, and test the origin, destination, unit, and final checkout result before publishing the method.
Calcurates documents
Table Rates as a condition-based option for building custom shipping calculations. Its Table Rates setup guide lists the FPUD algorithm: fixed per unit of distance. The documented calculation multiplies the configured amount by the distance used for the order.
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FPUD setup guide also states that this calculation requires a Google Distance Matrix API key in the External APIs settings. That dependency is essential: the rate needs a distance result before the per-unit calculation can be completed. Configure and test the external connection before treating the method as ready for live checkout.
The Table Rates guide allows calculations to be selected or combined, with multiple calculations summed. Combination is useful only when every component has a documented purpose. A fixed order component and a distance component should not overlap or recover the same cost twice.
The guide also lists distance range as a geo condition for a rate. This allows the store to define a rate that is valid only within an approved distance range. Conditions should reflect real coverage and operations, not arbitrary bands created only to make the table look complete.