Why is my spreadsheet slow or frozen?

1. The used range is bigger than your data

Every worksheet tracks a “used range” — the rectangle from the first cell you have ever touched to the last. If you once pasted data into row 900,000 and later deleted it, the sheet may still think it is a 900,000-row sheet.

Press Ctrl+End (Cmd+End on Mac) to jump to what the application thinks is your last cell. If that is far past your actual data, select the extra rows and columns, delete them — not just clear the contents — and save.

2. Conditional formatting applied to whole columns or rows

A conditional formatting rule applied to an entire column re-evaluates on every recalculation, even across a million empty cells. Narrow the rule’s range to where your data actually is.

3. Volatile formulas

Functions like NOW(), TODAY(), RAND(), OFFSET(), and INDIRECT() force a full recalculation of the workbook on almost every change, not just the cells that reference them. Replace them with static values where you do not need live updates, or isolate them to a small dedicated area of the sheet.

4. External links and cross-workbook references

Formulas that pull from another workbook — open or closed — add overhead every time the source changes or the file opens. Many small links compound quickly. Consolidate into one workbook, or replace the links with pasted values on a schedule.

5. Array formulas over large ranges

An array formula, or a modern dynamic-array function, that spills across a whole column instead of a defined range recalculates far more cells than necessary. Bound the range explicitly.

6. It actually is a row or column limit

If none of the above apply and the file is large, check it against the real limits: the row limit calculator measures your own file, and the full limits reference lists every platform with its source.