Rules & formulas

Make a field required, set limits, or validate what people enter

Updated Aug 12, 2026

Good data starts at the form. Validation rules stop bad entries before they reach your records. Think of an expense claim with no amount, a quantity of zero, or an end date before the start date. You define these rules in your workbook, in a sheet named Rules_, and Sheetward enforces them in the form.

Each row of the Rules_ sheet names a field and the rule that applies to it.

Add a rule

In your workbook, add a sheet named Rules_ (if it does not have one yet).
In each row, enter the field name.
In the Rule Type column, enter the rule type — for example required, min, max, between, or conditional / validation.
In the Value column, enter the rule logic.
Open the app and click Change app to upload the edited workbook.
The form now enforces the rule.

Which rule do I need?

Rule type	What it does	Everyday example
required	The field must be filled in.	An expense claim cannot be saved without an amount.
min / max	Sets a lower or upper limit on numbers or dates.	Order quantity must be 1 or more.
between	Keeps a value inside a range — write the Value column as `<low> and <high>` (numbers, dates, or other fields).	A discount must be between 0 and 100.
sensitive	Masks the value so only the last 4 digits show.	Fields holding SSN or card numbers.
conditional or validation	Your own check, written as logic using AND, OR, and similar.	"If payment type is Card, card reference is required."

Good to know

Sheetward checks date pairs such as start_date/end_date automatically — no rule needed to confirm the end date follows the start date.
Rules take effect after you re-upload the workbook through Change app.
The User Guide lists every available rule type in detail.