# Input Rules

Input Rules let you set extra requirements for what someone can enter in a field. They run live as the respondent types, on top of the field's built-in checks (the **Required** toggle and any type-specific checks like email format).

Find the **Input Rules** option in the field's settings panel in the form builder. Fields that hold no typed value (Content, Group, Signature, Payment) don't offer it, and Phone Number fields manage their own rules from the mask.

## Writing a Rule

Type one or more rules into the **Input Rules** field, separated by pipes (`|`):

```
min:3|max:50
```

```
alpha_num|max:20
```

```
regex:/^[A-Z]{2}-\d{4}$/
```

If a rule isn't valid, the form builder will reject it when you save the field. The check catches malformed rules rather than misspelled ones, so double-check the rule names against this page - and note the whole rule string is capped at 255 characters.

## Length

Constrain the length of text or the size of a number.

| Rule | Description |
|------|-------------|
| `min:3` | At least 3 characters (or numeric value ≥ 3) |
| `max:255` | At most 255 characters (or numeric value ≤ 255) |
| `size:5` | Exactly 5 characters |
| `between:5,20` | Between 5 and 20 characters |

## Numbers

Use these on **Number** fields, or on text fields where the value should look like a number.

| Rule | Description |
|------|-------------|
| `numeric` | Must be a number |
| `integer` | Must be a whole number (no decimals) |
| `decimal:2` | Must have exactly 2 decimal places |
| `gt:0` | Greater than 0 |
| `gte:1` | Greater than or equal to 1 |
| `lt:1000` | Less than 1000 |
| `lte:100` | Less than or equal to 100 |

## Letters & Patterns

Constrain which characters are allowed in a text value.

| Rule | Description |
|------|-------------|
| `alpha` | Letters only |
| `alpha_num` | Letters and numbers |
| `alpha_dash` | Letters, numbers, dashes, and underscores |
| `lowercase` | Must be lowercase |
| `uppercase` | Must be uppercase |
| `starts_with:DR-` | Must start with the given text |
| `ends_with:.pdf` | Must end with the given text |
| `regex:/^[A-Z]{2}\d{4}$/` | Must match the given regular expression |

## Format

Built-in checks for common formats.

| Rule | Description |
|------|-------------|
| `email` | A valid email address |
| `url` | A valid URL |
| `ip` | A valid IP address |
| `uuid` | A valid UUID |

## Choice

Restrict input to a fixed set of values.

| Rule | Description |
|------|-------------|
| `in:foo,bar,baz` | Must be one of the listed values |
| `not_in:test,example` | Must not be one of the listed values |

## Date

Use these on **Date** fields. Reference dates can be `today`, `tomorrow`, `yesterday`, or any date in `YYYY-MM-DD` format.

| Rule | Description |
|------|-------------|
| `date` | A valid date |
| `after:today` | After the given date |
| `after_or_equal:2026-01-01` | On or after the given date |
| `before:2030-01-01` | Before the given date |
| `before_or_equal:2026-12-31` | On or before the given date |

## Yes / No

Use these on toggle / yes-no inputs.

| Rule | Description |
|------|-------------|
| `boolean` | Must be a true/false value |
| `accepted` | Must be `yes`, `on`, `1`, or `true`. Handy for "I agree" style fields |
| `declined` | Must be `no`, `off`, `0`, or `false` |

## Tips

- [Input Masks](/docs/forms/input-masks) shape the value as it is typed; pair a mask with a `regex:` rule when you need to *enforce* the format on submit.
- Combine multiple rules with `|` to apply them all (e.g. `alpha_dash|min:4|max:20`).

## Related

- [Input Masks](/docs/forms/input-masks) - auto-format values as the user types
- [Form Validation](/docs/forms/validation) - overview of all validation options
- [Field Types](/docs/forms/field-types) - built-in validation per field type