Excel: File Freezing, Not Responding, or Running Slowly

If Excel freezes, shows "Not Responding," or is very slow to operate, here's how to diagnose and fix it. Common causes: - Spreadsheet has too many formulas (especially volatile ones like NOW(), TODAY(), INDIRECT()) - File has thousands of rows of complex calculations - Add-ins causing conflicts - Corrupted file or local Excel installation Step 1: Wait it out briefly Large recalculations can temporarily freeze Excel. Give it 30–60 seconds before force-closing. Check the status bar at the bottom — if it shows "Calculating: X%" it's still working. Step 2: Disable automatic calculation temporarily If the file is slow due to heavy formulas, press Ctrl + ` (grave accent) to switch to manual calculation mode, or go to Formulas > Calculation Options > Manual. Make changes, then press F9 to calculate when ready. Step 3: Open in Safe Mode Hold Ctrl and double-click Excel to open in Safe Mode. This disables add-ins. If Excel is fast in Safe Mode, an add-in is the culprit. To disable add-ins: File > Options > Add-ins > Manage: COM Add-ins > Go > uncheck add-ins one at a time to find the problem. Step 4: Check for unnecessary data - Look for formatting applied to entire columns or rows (not just cells with data) — this massively bloats file size - Press Ctrl + End to see where Excel thinks the data ends. If the cursor jumps far beyond your actual data, there's wasted space. Delete those empty rows/columns. Step 5: Save as a new file Corruption can build up in Excel files over time. Try File > Save As and save under a new name. The original may have accumulated bloat. Step 6: Repair the Office installation If Excel is slow on all files, the installation may need repair. Go to Settings > Apps > Microsoft 365 > Modify > Quick Repair. Step 7: Check system resources Open Task Manager (Ctrl+Shift+Esc). If RAM is maxed out while Excel is open, the computer may need a RAM upgrade to handle large spreadsheets.