# How to Make a Bootstrap Radio Button Group Required: Complete Guide
> Learn how to make a Bootstrap radio button group required. Ensure your form submits only after a selection is made by applying the required attribute to your radio inputs.
- Repository: [Tailwind Labs/tailwindcss](https://github.com/tailwindlabs/tailwindcss)
- Tags: how-to-guide
- Published: 2026-02-16
---
**Apply the `required` attribute to every radio input in the group that shares the same `name`; the browser treats the group as a single logical field and prevents form submission until one option is selected.**
When building forms with Bootstrap, ensuring that users select at least one option from a radio button group is a common requirement. Unlike single input fields, a radio button group requires special handling because HTML validation treats each input individually. This guide explains how to implement a required radio button group in Bootstrap 4 and 5, leveraging native HTML5 validation and optional JavaScript enhancements, with reference to the `tailwindlabs/tailwindcss` repository architecture for context on modern CSS framework design patterns.
## How HTML5 Validation Works for Radio Groups
The HTML specification allows the `required` attribute on individual form controls, not on groups. However, browsers implement a special rule for radio buttons: when multiple inputs share the same `name` attribute, they form a single **radio button group**.
When you apply `required` to every radio in that group:
1. The browser validates the group as a single logical field
2. Only **one** radio needs to be checked for the constraint to satisfy
3. If none are selected, the form submission is blocked with a native error message
This behavior works independently of Bootstrap and requires no JavaScript for basic functionality.
## Bootstrap 4 Implementation
In Bootstrap 4, radio buttons use the `.form-check` wrapper with `.form-check-input` and `.form-check-label` classes. To make the group required, add the `required` attribute to every radio input.
```html
```
The `novalidate` attribute on the form disables default browser tooltips, allowing Bootstrap's custom `.invalid-feedback` styles to display instead.
## Bootstrap 5 Implementation
Bootstrap 5 maintains the same class structure but updates the validation feedback mechanism. The `required` attribute placement remains identical.
```html
```
Note the use of `.form-check-inline` for horizontal layout and `.d-block` on the feedback div to ensure it displays below the group rather than adjacent to an individual radio.
## Enhancing Validation with JavaScript
While native HTML validation works without scripts, Bootstrap's custom feedback styles require JavaScript to toggle the `was-validated` class on the form. This pattern appears in modern CSS frameworks like Tailwind CSS as well, where validation states are managed through class application.
```javascript
// Bootstrap 5 validation enhancement
document.getElementById('exampleForm').addEventListener('submit', function (e) {
if (!this.checkValidity()) {
e.preventDefault();
e.stopPropagation();
}
this.classList.add('was-validated');
});
```
For dynamically added radio buttons, ensure the `required` property is set on new inputs:
```javascript
function enforceRequiredRadioGroup(groupName) {
const radios = document.querySelectorAll(`input[type="radio"][name="${groupName}"]`);
radios.forEach(radio => {
radio.required = true;
});
}
// Usage after AJAX injection
enforceRequiredRadioGroup('dynamicChoice');
```
## Edge Cases and Best Practices
When implementing required radio button groups in Bootstrap, consider these scenarios:
- **Multiple groups in one form**: Apply `required` to every radio in each distinct `name` group. Each group validates independently.
- **Accessibility**: Wrap radio groups in `