Calculator
File size estimator
A rough, before-you-export estimate of how big a CSV or XLSX file will be, based on row count, column count, and roughly how text-heavy the data is.
How this estimate works, and its limits
This is a rule-of-thumb calculation, not a measurement of your actual file: it multiplies your row and column count by an assumed average number of bytes per cell (roughly 9 bytes for mostly numeric data, 16 for a typical mix, 42 for mostly text), then adds separator and newline overhead for CSV. The XLSX estimate applies a rough compression factor, since XLSX is a zipped XML format, actual compression varies a lot by content.
Real files vary based on actual field lengths, encoding, and formatting, so treat this as a planning estimate, not an exact prediction.
Google Sheets’ practical import ceiling is around 100MB regardless of cell count, which is one reason file size matters even when you’re technically under the row limit.
Already know it’s too big?
Open it in openbigcsv.com