Guide

Why ad spend in two currencies cannot be added up

Run more than one ad account and the exports stop agreeing about what a number means. Spend is not a count; it is a count of something, and two files can put different somethings in the same column. A spreadsheet will still add them, quite happily, and hand back a figure that is not the amount of money you spent in any currency that exists.

The three ways a file tells you

Worth separating, because they are fixed in different places. The first two are export scope — you asked for two accounts at once. The third is not: one account, one currency, and the file still disagrees with itself, because the header and the column were filled in by different parts of the report.

Symbols deserve their own warning. A symbol is not a currency. $ is shared by the US, Canadian, Australian and Singapore dollar, and ¥ by the yen and the yuan. Seeing one symbol tells you nothing; seeing two tells you exactly one thing — that more than one currency is in the file. That is the only claim a symbol can support, and it is the only one worth making from it.

Worked examples

Invented files, real parser. Each verdict below comes from dropping the CSV printed beside it into the same function our CSV check calls in your browser, so the wording here changes if the tool ever changes its mind. The last row is the ordinary case, included on purpose: this is not a tool that refuses files.

Two ad accounts merged into one file
A Currency column that holds more than one code
```
Day,Campaign name,Amount spent,Currency
2026-08-01,US prospecting,120.00,USD
2026-08-02,JP prospecting,18000,JPY
```
The column “Currency” holds JPY, USD. This file states more than one currency. Every total on this page would be a sum of different units, so nothing is shown. Export one ad account at a time.
No currency column, but the amounts carry symbols
Currency symbols inside the spend cells disagree
```
Day,Campaign name,Amount spent
2026-08-01,US prospecting,$120.00
2026-08-02,EU prospecting,€120.00
```
The amounts carry more than one currency symbol ($ €). This file states more than one currency. Every total on this page would be a sum of different units, so nothing is shown. Export one ad account at a time.
One account, but the file contradicts itself
The spend header names one currency, the Currency column names another
```
Day,Campaign name,Amount spent (USD),Currency
2026-08-01,US prospecting,120.00,EUR
2026-08-02,US prospecting,120.00,EUR
```
The file contradicts itself: USD (Amount spent (USD)), EUR (Currency). This file states more than one currency. Every total on this page would be a sum of different units, so nothing is shown. Export one ad account at a time.
One account, one currency — the ordinary case
Every row states the same code
```
Day,Campaign name,Amount spent,Currency
2026-08-01,US prospecting,120.00,USD
2026-08-02,US prospecting,120.00,USD
```
Read as USD. Every total below it is in that one unit.

Why nothing is shown instead of a total with a warning

A caveat under a wrong number does not repair the number. It is read once, by the person who dropped the file in, and never again by anyone who is sent the screenshot. Every ratio on the page inherits the fault silently: a cost per result computed from a mixed total is wrong by whatever share of the spend came from the other currency, and it looks exactly like a cost per result that is right.

So the file is checked for this before a single row is turned into money, and the answer names the evidence — which column, which codes — rather than announcing the conclusion. The conclusion is not actionable. The column is.

Converting to one currency is a different number, not a repair

The obvious move is to pick a rate and convert. It produces something you can add, and it is the right call for a finance report — but be clear about what you now have. The converted total depends on which day's rate you used and on whether you used one rate for the window or the rate on each row, and those give different answers from the same spending. None of them is what the ad account was charged. For a bookkeeping question that is fine. For did this campaign clear its cost per result, the conversion adds a second source of error on top of the one you were trying to measure.

There is also a quieter trap underneath. Currencies do not agree on how many decimal places they have — the yen has none, most others have two — so a pipeline that stores money as a plain decimal number and converts along the way can land a hundred times off without anything looking wrong. Money is best kept as a whole number of the smallest unit the currency actually has, tagged with which currency that is. Do that and adding two currencies stops being a bug you have to remember: it becomes impossible.

What to do with the export you have

Export one ad account at a time and read each on its own — comparing cost per result between two accounts does not require them to share a currency, only that each is right within itself. If the file contradicts itself while covering a single account, the fix is the export, not the accounts: drop the currency column and let the spend header carry the code, or the other way round. You can check either in the browser you already have open — our CSV check reads the file locally and sends it nowhere. If the columns themselves are the problem, that is the column-by-column guide, and if the question is whether the window holds enough to read at all, that is the one on judging a campaign.

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