NOW() and TODAY() in Google Sheets™: the hidden cost of volatile functions
Most formulas recalculate only when their inputs change. Volatile functions recalculate on every change, anywhere in the workbook. In Google Sheets™ the main ones are NOW(), TODAY() and RAND(): touch any cell, and every one of them, plus everything downstream of them, calculates again.
One =TODAY() in a corner is harmless. Dozens of them scattered through a big sheet, each feeding chains of dependent formulas, can make every keystroke wait.
Check by hand
- Press Ctrl+H (Find and replace), search for
NOW(), thenTODAY(), thenRAND(), with "Also search within formulas" ticked. - For each hit, ask: does this need to be live, or just stamped once?
Keep the timestamp, drop the cost
- One-off stamps: replace the formula with a static value. Type the date, or use the date/time shortcuts and leave the value in place.
- "Last updated" cells: keep one volatile cell and point every formula at it, instead of repeating the function everywhere.
- Random values: generate once with
RAND(), then copy and Paste special → Values only. - Ages and day counts: if they only need to be right when you look, calculate them on demand rather than live.
Find every volatile cell
Sheet Speed Checker™ grades a Google Sheets™ file and shows where the time goes, including every volatile function and what depends on it. Checking the active sheet, the grade, every finding and Undo are free.
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Google, Google Sheets™ and Google Workspace™ are trademarks of Google LLC. Sheet Speed Checker is not affiliated with or endorsed by Google.