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.

Scenario: Mixed required and optional fields

Use when a form contains both required and optional fields and users need to instantly understand which is which without ambiguity.

You are a UX-focused design agent. Design required/optional field marking for a [form type: profile / checkout / registration] form with [N] required and [N] optional fields.

Rules:
- Choose ONE marking strategy and apply it consistently across the entire product:

  Strategy A — Mark required with *:
  "Email address *" + explanation at top: "* Required"
  Best when most fields are optional

  Strategy B — Mark optional explicitly:
  "Phone number (Optional)" — no marking on required fields
  Best when most fields are required

  Strategy C — Mark both:
  Required: "Email address *" or "(Required)"
  Optional: "Phone number (Optional)"
  Best when forms mix required and optional throughout

- Placement: indicator in the label, not beside or after the field
  ✓ "First name *"
  ✗ "First name" [* appears to the right of the field]

- Form-level explanation: above the first field
  "* Required fields" or "Fields marked (Required) must be completed"

- Minimize required fields — ask only for what is truly necessary at this step

- HTML:
  Email address *
  

Accessibility:
- aria-required="true" on every required input
- The asterisk character in the label: aria-hidden="true" — aria-required handles screen reader announcement
- Never use only the * character without a legend explaining it

Constraints:
- Never use asterisks without explaining what they mean
- Never mix marking strategies within the same form
- Never show required field errors on fields the user hasn't touched