Open and calculate spreadsheets locally

Build a calculation small enough to check by hand

The practice order has two lines. Three notebooks at 4.5 each cost 13.5. Two folders at 6 each cost 12. Adding those lines gives 25.5. These independently calculable values make it easy to spot an incorrect reference before the sheet grows.

A number format changes how a value is displayed, not what that value represents. Currency formatting does not convert between currencies. Keep the unit of measure or currency clear in the column heading.

Investigate a formula instead of hiding its error

If a formula displays #ERROR, first check its cell addresses, parentheses and whether the function is supported. The local calculator handles arithmetic and simple single-range functions such as SUM and AVERAGE. Desktop formulas using lookups, external links or macros need a more capable calculation environment.

CSV brings a table of values rather than the full structure of an Excel workbook. Identifiers such as 00124 and dates written as 03/04/2026 deserve special attention because applications can interpret them differently. Compare those cells against the source instead of judging an import only by its grand total.

Keep the full-workbook boundary in mind

The editable region is at most 2,000 rows and 100 columns per sheet. Imported overflow data can be retained in downloads during the same tab session, but inserting or deleting rows or columns on that sheet removes this preservation path.

For a large workbook, retain the original, avoid structural edits here and inspect the exported range before relying on it. Download XLSX before refreshing or closing the tab; the local draft is not a full-workbook backup. Review formulas and advanced structures in the receiving spreadsheet application.

Try the workflow

1. Enter Item, Quantity, Unit cost and Line total in A1:D1.
2. Enter the two example item rows and their multiplication formulas.
3. Enter =SUM(D2:D3) in D4 and compare it with the hand-calculated total of 25.5.
4. Download XLSX and inspect the values, formulas, sheet names and row count in the receiving app.

Inspect the downloaded copy

• The formulas reference Quantity and Unit cost on the correct row.
• The total includes exactly the intended line totals.
• Leading zeros, date-like text and large identifiers match the source.
• The downloaded workbook contains the expected sheets and data range.

Limits of this editor

• Supported calculations are arithmetic, cell references and SUM/AVERAGE/MIN/MAX/COUNT over a single range; not full Excel formula compatibility.
• Editable area is 2,000 rows by 100 columns per sheet.
• Overflow preservation applies only during the current session and ends for a sheet when row/column structure is changed.
• The editor rejects workbook inputs above 50 MiB, shown as 50 MB in the interface.
• CSV input does not include the workbook formatting and multiple sheets of an XLSX source.

Questions about this workflow