Can Google Sheets automatically insert a timestamp when a cell changes?

Not with an ordinary formula — NOW() and TODAY() recalculate on every change, so the time never stays put. To freeze the moment of an edit you need a self-referencing formula with iterative calculation turned on, an onEdit Apps Script trigger, or an add-on such as SmartStamp.

Why does my timestamp formula keep changing every time I edit the sheet?

NOW() and TODAY() are volatile functions: they re-evaluate on every recalculation, so a plain =NOW() cell always shows the current time, not the time of a past edit. Capturing a fixed timestamp requires a circular formula guarded by iterative calculation, or writing the value once with a script or add-on.

Can I record which user edited the row, not just when?

A formula cannot read the editing user. An onEdit Apps Script can call e.user.getEmail(), but that is usually blank unless the editor is in the same Google Workspace domain as the file owner. SmartStamp can stamp the editing user's email address into a column.

Auto Timestamp When a Cell Changes in Google Sheets (3 Methods)

You want column C to record the date and time each row in column B was last edited — a “last touched” stamp that then stops moving. A bare =NOW() is volatile: it re-reads the clock on every recalculation, so it can never hold a past moment — no fixed stamp. TODAY() is the same. You have three options.

Method 1 — A self-referencing formula with iterative calculation

No script, but you have to change a file-wide setting.

File → Settings → Calculation, set Iterative calculation to On, max iterations 1.
In C2, enter: =IF($B2="", "", IF(C2="", NOW(), C2)) and fill it down column C.
Format column C as date-time (Format → Number → Date time).

The formula references its own cell: while C2 is empty it writes NOW() once, then keeps returning its own stored value.

Watch out for:

Iterative calculation is a whole-file setting. It changes how every circular reference in the spreadsheet behaves and can mask genuine mistakes.
It stamps the first time a row gets a value and never again — it can’t record a later edit, and clearing then retyping B2 resets the stamp.
A stray recalculation or a copy-paste over column C can wipe the frozen values with no undo.
It can’t capture who made the edit, and it only reacts to values, not to formatting or checkbox changes.

Method 2 — An onEdit Apps Script trigger

Free and it stays with the file — but you also own the upkeep, and one script only covers one spreadsheet. Open Extensions → Apps Script, paste this, and save:

/** * Stamp column C with the current date-time whenever column B * on "Sheet1" is edited. Clears the stamp if B is emptied. */ function onEdit(e) { var sheet = e.range.getSheet(); if (sheet.getName() !== "Sheet1") return; var watchCol = 2; // B var stampCol = 3; // C if (e.range.getColumn() !== watchCol || e.range.getRow() < 2) return; var stampCell = sheet.getRange(e.range.getRow(), stampCol); if (e.value === undefined) { stampCell.clearContent(); // B was cleared } else if (!stampCell.getValue()) { stampCell.setValue(new Date()); // stamp once } }

Watch out for:

A simple onEdit only fires on a manual edit by someone with edit access — not on Google Form submissions, not for viewers, not for changes made by other scripts.
Running the function yourself from the editor throws, because e is undefined outside a real edit.
Pasting or filling down a block, e.range covers many rows; this version only stamps the row you land on — handling the whole range is more code.
You get one onEdit(e) per project. A second watched column, another sheet, or a different rule all pile into that same function as more branches — it only gets harder to follow.
The script lives in this spreadsheet only — every other file you want stamped, you paste and re-authorise it again, and so does each collaborator.
e.user.getEmail() is usually blank unless the editor is in your Workspace domain.

Method 3 — The SmartStamp add-on

Install once and it works in every spreadsheet on your account — now and later — set up from a panel, no code, with the edge cases already handled. In SmartStamp you:

add one or more watched ranges — each its own sheet, column, row range and rule, configured side by side instead of branching a single script;
choose the stamp value — a timestamp, your own fixed text, or the editing user’s email;
set a condition so it only stamps when the edit is a number, non-empty text, a date, or a ticked checkbox;
toggle options: don’t overwrite an existing stamp, delete the stamp when the watched cell is cleared, require a specific value, or backfill rows that already have data.

Paste and fill-down are stamped across the whole affected range, and the configuration is saved per sheet, so it keeps running with no code to maintain.

Shared limit: methods 2 and 3 both build on Google’s edit events, which do not fire for Google Form submissions that write straight into the sheet. Stamping those needs a separate onFormSubmit trigger.

Which method should you use?

	Iterative formula	onEdit script	SmartStamp
Setup	File-wide setting + formula	Paste & maintain code	Panel, no code
Stamps a later edit, not just the first	No	Yes (with logic)	Yes
Handles paste / fill-down	Fragile	Extra code	Built in
Can stamp the editor’s email	No	Domain only	Yes
Conditions (number / text / date / checkbox)	No	Extra code	Built in
Several watched ranges or rules	A formula per column	All in one `onEdit`	Each configured on its own
Available in your other spreadsheets	No — per file	No — paste per file	Yes — every sheet on your account
Upkeep	Watch for wiped values	You own every fix	Updates itself
Cost	Free	Free	Free plan, paid plans from €1.99/mo

The iterative formula is fine for a create-once “added on” date. Reach for an onEdit script if you’re comfortable maintaining a bit of code and only need one sheet handled. SmartStamp is the choice when the stamp has to survive pasting, react to a real condition, or record who made the change.

SmartStamp is launching soon

Automatic timestamps, custom values and editor email in Google Sheets — set up once per sheet, no script to maintain.

See how it works →

Add a timestamp when a cell changes in Google Sheets

Method 1 — A self-referencing formula with iterative calculation

Method 2 — An onEdit Apps Script trigger

Method 3 — The SmartStamp add-on

Which method should you use?

SmartStamp is launching soon