Required vs optional fields

Forms are one of the most common sources of user frustration. A frequent issue is unclear indication of which fields are required and which are optional.

There is ongoing debate among UX practitioners:

• Some recommend marking only optional fields, to reduce visual noise.
• Others argue for marking both required and optional fields, ensuring clarity and consistency across different forms.

Marking both types can help users quickly orient themselves, especially in products where some forms mix required and optional fields, while others contain only required ones. Even in obvious cases such as login forms, marking required fields may not be strictly necessary, but it also isn’t an error if done for consistency.

Whenever possible, minimize required fields. Still, in contexts such as surveys or registrations, optional fields may be unavoidable (for example: alternative contact methods).

Guidelines for handling required and optional fields.

Mark both required and optional fields

Consistently marking both required (* or “Required”) and optional (“Optional”) fields reduces confusion, especially across products with different types of forms.

Acceptable approaches include:

• Marking required fields with * and explaining at the start of the form (“* Required fields”).
• Labeling explicitly: “Name (required), Phone number (optional)”.

References:

• WCAG 3.3.2: Labels or instructions
• E-commerce checkouts – Baymard Institute

Minimize the number of required fields

Ask only for essential information. Each additional required field increases friction and drop-off rates.

References:

• Forms that work – Caroline Jarrett & Gerry Gaffney

Maintain consistency across all forms

If you choose to mark only optional fields, do so everywhere. If you choose to mark both required and optional, apply the same rule consistently across the product.

References:

• Website forms usability – Nielsen Norman Group

Support accessibility with programmatic labels

Use aria-required="true" for required fields and provide text or labels for optional ones. Screen readers should announce “required” or “optional.”

References:

• Forms tutorial – W3C WAI

Provide inline guidance

Use short helper text below the input to explain why a field is required or how the data will be used. This builds trust and reduces abandonment.

References:

• Forms that work – Caroline Jarrett & Gerry Gaffney

Maintain sufficient contrast

Indicators such as “Required” or “Optional” must have at least 4.5:1 contrast ratio against the background.

References:

• WCAG 1.4.3: Contrast minimum

Special case: single-field

If the form has only one field, it should be treated as required by default, no need to label it. The only exception is when the single field is genuinely optional (for example: “Promo code (optional)”).

References:

• Designing UX: Forms – Jessica Enders

Frequent mistakes in marking required and optional fields.

Using only an asterisk without explanation

Users may not understand what it means, and screen readers often miss it.

Inconsistent labeling across a form

Mixing approaches (sometimes marking required, sometimes optional) confuses users.

Relying on color only to differentiate fields

Fails accessibility and creates problems for users with color vision deficiencies.

Key takeaways for handling required and optional fields.

• Always indicate required or optional fields clearly, both visually and programmatically.
• Minimize the number of required inputs.
• Use consistent labels and helper text to build trust.
• Never rely on color alone; maintain proper contrast for all indicators.

Even small details in form labeling can significantly improve usability, accessibility, and completion rates.