The basic Excel formula is simple: multiply the amount by a rate that is expressed as target currency for one unit of source currency. For example, if 1 EUR equals 1.08 USD, then 100 EUR equals 108 USD. The rate in that example is an input you should check and replace.
It includes direct conversion, reverse conversion, and a small editable lookup table.
Direct currency conversion
Put the amount in one cell and the rate in another. Keep the rate direction visible next to the input so someone reviewing the sheet can tell what the number means.
In the downloadable workbook, B4 is the amount and B7 is the rate: target currency for one unit of source currency. If the amount is 100 and the rate is 1.08, the result is 108.
Reverse the conversion
If you have the rate in the other direction, divide by the original rate. This keeps the relationship clear and avoids maintaining two independent numbers.
The workbook also shows the reverse rate as =1/B7. That result is calculated from the editable input, so changing the rate updates both directions.
Look up a rate from a table
A small table works well when you maintain a known set of currency pairs. Store the source currency, target currency, and the rate direction in separate columns. On the workbook's Examples sheet, the formula below matches the currencies in B13 and B14 against the rate table. This keeps EUR to USD from accidentally using USD to EUR.
In newer Excel versions, Enter is enough for this formula. Older versions may require array-formula entry. For a larger table, use a structured Excel table and XLOOKUP with a combined key, as described in Microsoft's XLOOKUP reference.
Refresh rates with Power Query
Formulas calculate from the values already in the workbook. They do not fetch a new rate by themselves. When you need a refreshable table, use Power Query to load a response into a separate table and keep your conversion formulas pointed at that table.
- Load a small, clearly named rate table and keep the source date beside each rate.
- Refresh the query when you need new values; review the result before using it in a report.
- Keep API keys out of shared workbooks. Use an authenticated server-side query or a proxy when a key is required.
- For a date-specific value, use the historical exchange rate lookup and record the date and source.
See the longer Excel exchange rates guide for a Power Query walkthrough. Microsoft's Power Query overview explains the Excel refresh workflow.
Check the rate before you use it
Exchange rates can differ by source, time and market session. The workbook marks its sample rate as illustrative on purpose. Replace it with a value you have checked, and keep the source and observation date with the rate if the result needs to be reproducible.