Data Validation

Data validation adds interactive in-cell controls — checkboxes, dropdown lists, and a date picker — and guards a range against bad input. A control is not a floating object on top of the grid; it's a special rendering of the cell's own value, so it survives sorting, filtering, and copying, and works directly in formulas.

Open the Data Validation Panel

Open the right-side Data validation panel in either of these ways:

• Click the Data validation icon in the toolbar
• Right-click a cell and choose Data validation

On a narrow screen the toolbar collapses its extra tools into a More formatting options (⋮) menu — open it and choose Data validation there.

Add a Rule

1. Click Add in the panel. This creates a Dropdown rule — change the criteria in step 3 if you want a different one
2. Set Apply to range — type a range like B2:B100, or click Use selected range to fill it from your current selection, then click Apply
3. Pick a Criteria (see below)
4. Choose what happens on invalid input — Show a warning or Reject the input

You can add several rules per sheet; each appears as a card you can edit or delete.

Criteria

Checkbox

Turns each cell in the range into a checkbox storing TRUE or FALSE.

• Click the box to toggle it
• Select one or more cells and press Space to toggle them together
• Because the value is a real boolean, =COUNTIF(B2:B100, TRUE) and similar formulas work as expected

Dropdown

Restricts the cell to a list of options you type, one per line. A dropdown arrow appears in the cell.

• Click the arrow — or press Alt+↓ — to open the option picker
• Toggle Show dropdown arrow to hide the arrow while keeping the rule
• Values outside the list are flagged (warning) or blocked (reject), per the rule's invalid setting

Date

Validates that the cell holds a date, with an operator:

Operator	Meaning
is a valid date	Any valid date
date is	Equals a specific date
date is before / date is on or before	Earlier than a date
date is after / date is on or after	Later than a date
date is between / date is not between	Within (or outside) two dates

Double-click a date-validated cell to pick a value from a calendar popover instead of typing it.

Number

Validates numeric input with an operator:

• is a valid number
• is equal to / is not equal to
• greater than / greater than or equal to
• less than / less than or equal to
• between / not between

Text

Validates text input:

• contains / does not contain
• is exactly
• is valid email
• is valid URL

Handling Invalid Input

List, date, number, and text rules choose how to treat a value that fails validation:

• Show a warning — the value is accepted and stored
• Reject the input — a typed entry is refused and the cell keeps its previous value

Checkbox rules have no such choice, because there is nothing for them to reject: the cell is a checkbox, and any value it holds is treated as valid.

For the other four kinds, a cell holding a value that fails its rule is flagged with a small red triangle in its top-right corner — the same corner the yellow comment marker uses. The marker is not exclusive to warning rules: an invalid value can still reach a reject-mode cell by paste, by the API, or by already being there when the rule was added, and the marker is what makes that visible. A formula is checked by its computed result at render time rather than by its text, so a formula that returns an invalid value gets the marker instead of being rejected.

TIP

Use warning while cleaning up existing data so nothing is lost, and switch to reject once a column should only ever hold valid values.

Remove a Rule

Open the Data validation panel and click the ✕ button on the rule's card. The in-cell controls for that range are removed and the cells go back to plain values.