How cross currency rates work

A cross rate combines two quoted rates through a shared currency. AussieSpend uses a Cotizave USD/AUD reference and, when available, a Cotizave USD/foreign-currency reference to derive an AUD comparison rate. That is a calculation from two observations, not a direct AUD/foreign quote.

The calculation

If one USD buys A Australian dollars and one USD buys F units of a foreign currency, one foreign unit is worth A ÷ F AUD. To convert an amount in foreign currency to AUD, multiply that amount by A ÷ F. The reverse AUD to foreign rate is F ÷ A.

For a purely mathematical example, if A were 1.5 and F were 100, one foreign unit would be 0.015 AUD. These numbers are illustrative; the live converter fetches actual available Cotizave observations.

Why the source time matters

The two observations can have different update times. A derived result should expose both source timestamps and be unavailable if either source is missing or too old under our freshness rules. It is a reference only. A bank, card network or merchant may use a different rate at a different time and add fees.

See our full methodology and use the fee calculator to model a card scenario. Source: Cotizave. Reviewed 31 October 2026.