### [How to Compare Two Time Fields in a Form](https://wpforms.com/developers/how-to-compare-two-time-fields-in-a-form/)

**Published:** December 7, 2022
**Author:** Editorial Team

**Excerpt:** This tutorial will show you how to compare two time fields and calculate the difference in hours to be stored inside a hidden field. 

**Content:**

## Introduction

Are you interested in comparing two **Time** fields within your form and capturing the calculated difference in your entry? Look no further! This tutorial is tailor-made for you. We’ll guide you through the process of configuring your form and provide you with the necessary PHP snippet to seamlessly implement this functionality on your site.

## Creating the form

To get started, let’s create a new form and configure our fields. In this guide, we’ll be designing a form specifically for reserving party rooms. Our snippet will utilize a **Hidden Field** to automatically calculate and append the total reserved hours to the entry. This feature is particularly useful for the accounting team, providing a straightforward overview for invoicing.

If you’re unfamiliar with creating forms, you can refer to [this documentation](https://wpforms.com/docs/creating-first-form/ "Creating Your First Form") for assistance.

In our form setup, we’ll include standard fields such as **Name**, **Email**, **Address**, and **Phone**. Additionally, we’ll incorporate a **Dropdown** field for room selection, a **Date** field for the reservation date, two **Time** fields for specifying the start and end times of the reservation, and finally, a concluding **Hidden Field** to store the calculated total hours using our snippet.

![begin by creating your form and adding your fields](https://wpforms.com/wp-content/uploads/2022/12/wpforms-compare-two-times-create-form.jpg)

## Adding the snippet

Next, we’re going to add the snippet to our site. If you’re not sure where or how to add snippets, [please check out this tutorial](https://wpforms.com/developers/how-to-add-custom-php-or-javascript-for-wpforms/ "How to Add Custom PHP or JavaScript for WPForms").

```

/**
 * Compare two time fields in a form
 * 
 * @link https://wpforms.com/developers/how-to-compare-two-time-fields-in-a-form/
 */

function wpf_wpforms_update_total_field( $fields, $entry, $form_data ) {

	// Only run on my form with ID = 731
	if( 731 != $form_data[ 'id' ] ){
        return $fields;
    }
	
    // Field ID 37 is the first time field of the form
    $start_time = strtotime( $fields[37][ 'value' ] );
    
    // Field ID 38 is the second time field of the form
    $finishing_time = strtotime( $fields[38][ 'value'] );
	
    // Field ID 41 is the hidden field that will calculate the difference
    // between the two time fields and store the hours inside a hidden field of the entry
	$fields[41][ 'value' ] = round(abs($finishing_time  - $start_time)/ 3600,2) . __( ' Hours', 'text-domain');

	return $fields;
}

add_filter( 'wpforms_process_filter', 'wpf_wpforms_update_total_field', 10, 3 );
```

This snippet will only run on the form ID **731**. It will look at the two **Time** fields of the form, which are the IDs **37 and 38**. Using the `round` function, it will calculate the difference between the two times and store the difference inside the **Hidden Field**

You’ll need to update the snippet to match the form and field IDs that you have in your form. If you need help in where to find these IDs, [please check out this tutorial](https://wpforms.com/developers/how-to-locate-form-id-and-field-id/ "How to Locate Form ID and Field ID").

![using this snippet you can now two time fields in a form](https://wpforms.com/wp-content/uploads/2022/12/wpforms-calculate-two-times.jpg)

Would you like to also compare two dates? Take a look at our tutorial on [How to Compare Two Dates in the Same Form](https://wpforms.com/developers/how-to-compare-two-dates-in-the-same-form/ "How to Compare Two Dates in the Same Form").

## Related

Action Reference: [wpforms\_process](https://wpforms.com/developers/wpforms_process/ "Using the wpforms_process action")

**Categories:** Tutorials

**Tags:** PHP

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