The Scenario
You're the ops manager for a global e-commerce company. The payment run is today at 4 PM and you have an Excel sheet — well, a Google Sheet — with 50 vendor invoices in EUR, GBP, JPY, and AUD. Finance needs every invoice converted to USD at today's rate before you can approve. Your usual approach is to look up today's exchange rate for each currency, write it into a helper column, and then multiply manually. Four currencies, four lookups, 50 rows of math.
The bad version:
- You go to a currency conversion site, look up EUR/USD for today, copy the rate into a cell, and write a formula in the USD column for the EUR rows.
- You realize you forgot to account for JPY — the rate is in the wrong units (per 100 yen, not per yen) and your first dozen USD conversions are off by two orders of magnitude.
- You fix the JPY rows, recheck GBP, and then realize the AUD rate you used was from this morning's open and the rates have moved 0.4% since then. Finance wants today's close, not today's open.
The payment run is in 90 minutes. The data was never the problem — the manual lookup process was.
The Easy Way: One Prompt in SheetXAI
SheetXAI is an AI agent that lives inside your Google Sheet. It reads the currency and amount columns, calls the Polygon.io forex API for real-time rates, and writes the USD conversion and the rate used into the columns you specify — for all 50 rows in a single pass.
For each row in my "Vendor Invoices" sheet, convert the amount in column B from the currency in column C to USD using today's real-time Polygon.io forex rate and write the USD equivalent into column D.
What You Get
- Column D: USD equivalent for each invoice, calculated at the live Polygon.io rate.
- Column E (if requested): the exchange rate used, labeled with the currency pair and timestamp so Finance has an audit trail.
- Rows where the currency in column C is already USD are passed through with USD amount unchanged and column E marked "No conversion needed."
- If a currency code in column C is unrecognized, the row is flagged in column F with "Unknown currency — review."
What If the Data Is Not Quite Ready
I want the conversion rate and the USD amount written into separate columns
Read the 50 invoice rows in my Excel sheet, convert each foreign-currency amount to USD using Polygon.io live rates, and write the conversion rate used and USD amount into columns E and F.
Some rows have missing currency codes and I need to flag them before running the conversion
For each row in the "Vendor Invoices" sheet, check if column C has a valid currency code. If column C is blank or contains an unrecognized value, write "Missing currency — skip" into column D and skip the conversion for that row. Run the USD conversion for all valid rows using Polygon.io live rates.
I need a summary row at the bottom showing total USD exposure by currency
Convert all invoices in the "Vendor Invoices" sheet to USD using Polygon.io live rates. Write the USD amount into column D and the rate used into column E. Then add a summary block below the last row showing total USD exposure grouped by original currency.
Convert everything to USD, flag invoices over $50,000, and add a column for the approver to sign off
For each row in the "Vendor Invoices" sheet, convert the amount in column B from the currency in column C to USD using Polygon.io live rates. Write the USD amount into column D. In column E, write "Requires senior approval" for any invoice where the USD amount exceeds 50000, otherwise leave blank. Add a blank "Approver Sign-off" column in F.
One prompt does the conversion, the threshold flag, and the approval scaffold all at once.
Try It
Open your vendor invoices Google Sheet and Get the 7-day free trial of SheetXAI. Ask it to convert every foreign-currency amount to USD using live Polygon.io forex rates and add an audit trail column. For FX technical data for your currency tracking, see the spoke on importing forex OHLC bars. For the full partner overview, see the Polygon.io hub.