How we calculate rates

Here's where each rate comes from, how AUD cross rates are derived, and the formulas behind every calculator.

Current data sources

Exchange rate data is powered by Cotizave. The public V1 country snapshot supplies USD/AUD in its AU entry, without an API key, plus USD references for the other supported currencies. We derive non-USD AUD rates as USD/AUD ÷ USD/foreign currency. These are calculated cross rates, not directly published AUD pairs. The public response does not include a V2 rate ID. With a private V2 key, the Worker can request the separately identified au-official rate instead; a key is not required for today's public USD/AUD reference.

The calculator shows the source ID or method and the original update time. It checks each source's published staleness limit and shows no result if a required rate is missing or too old. Cached data may be fetched up to two hours earlier for the public snapshot or one hour earlier for V2; the source publication time remains visible. No fixed sample rate is substituted.

Reference rate vs. what you'll actually be charged

The reference rate is a published Cotizave data point or a cross rate derived from two such data points. It is a baseline for comparison, but it is not the rate your card issuer will apply. Three things can separate the reference rate from your actual statement:

• Exchange rate markup — a percentage built into the rate itself, rather than shown as a separate charge.
• Foreign transaction fee — a percentage some cards charge on top of the converted amount.
• Fixed fee — a flat charge some providers apply per transaction or ATM withdrawal.

Read exchange rate markups, explained for more detail on the first one specifically.

The formulas

These are the exact calculations behind each tool, so you can check our working or reproduce it yourself.

Currency converter

foreign amount × AUD per foreign unit = AUD amount, or AUD amount ÷ AUD per foreign unit = foreign amount for the reverse direction. Used on the converter and the individual currency pages.

Fee calculator

1. Reference conversion: purchase amount × AUD per foreign unit = reference AUD
2. Add the rate markup: reference AUD × (markup% ÷ 100) = markup amount
3. Add the card fee, applied to the converted amount: (reference AUD + markup amount) × (fee% ÷ 100) = fee amount
4. Total: reference AUD + markup amount + fee amount + fixed fee = estimated total

Used on the fee calculator.

Travel budget calculator

daily spend × days × travellers = local currency total, then multiplied by AUD per foreign unit. Used on the travel budget calculator.

AUD or local currency comparison

Compares the merchant's quoted AUD price plus any card fee on that AUD charge against the estimated total for paying in local currency (Cotizave reference conversion + your card's markup + its fee on the local-currency charge). Whichever total is lower in the entered scenario is cheaper. Used on the AUD or local currency tool.

What we don't do

We don't exchange money, process payments, or give personal financial advice. The calculator shows an unavailable state when its source is unavailable. Editorial worked examples are hypothetical and labelled as such. See our terms and privacy policy for the rest.