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Calculating the time difference between two dates is a common requirement for reservation bots (nights stayed), age verification, or event countdowns. This guide uses Unix Timestamps (total seconds since January 1, 1970) to perform accurate date arithmetic.

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Prerequisites

Before you begin, ensure you have:
  • Basic knowledge of the Flow Builder.
  • Understanding of Custom Fields and Variables.

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Step-by-Step Guide

1

Collect the Dates

Obtain the two dates you wish to compare and store them in Custom Fields.
  • Start Date: {{check_in_date}} (e.g., user input or system date)
  • End Date: {{check_out_date}}
Ensure you capture these dates using a Date Input type to guarantee they are in a valid format before proceeding.
2

Convert Dates to Seconds

To perform math, you must convert the readable dates into a numerical format (Unix Timestamp).
  1. Add a new Action block in your flow.
  2. Navigate to Tools > Format Date.
  3. Configure the Check-In date:
    • Date & Time: Select {{check_in_date}}.
    • Format: Enter "U" (Unix Timestamp format).
    • Save to: Create a new number field {{check_in_seconds}}.
  4. Repeat this for the Check-Out date to create {{check_out_seconds}}.
3

Calculate the Difference

Subtract the start time from the end time to get the duration in seconds.
  1. Add a Set Custom Field action.
  2. Set the Operation to Set to (or Calculate Formula).
  3. Enter the subtraction formula:
{{check_out_seconds}} - {{check_in_seconds}}
  1. Save the result to a variable named {{difference_in_seconds}}.
4

Convert Seconds to Days

Convert the raw seconds back into a human-readable number (Days).
  1. Add another Set Custom Field action.
  2. Divide your seconds result by the number of seconds in a day (86400).
{{difference_in_seconds}} / 86400
  1. Save this to {{difference_in_days}}.
Why 86,400?There are 60 seconds in a minute, 60 minutes in an hour, and 24 hours in a day. 60 * 60 * 24 = 86,400 seconds.
5

Display the Result

Use the final variable to display the result to your user.Your stay is for {{difference_in_days}} nights.

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Advanced Usage

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Calculating Age

To determine a user’s age, compare their birth date against the current time.
  1. Date 1: User’s {{birth_date}}.
  2. Date 2: Current Date (Use the now variable or system time).
  3. Calculate the difference in seconds.
  4. Divide by 31,536,000 (approximate seconds in a year).

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Countdown Timers

For future events:
  1. Date 1: Current Date.
  2. Date 2: Event Date.
  3. Subtract Current Date from Event Date.
  4. Convert the remaining seconds into Days, Hours, or Minutes as needed.

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Frequently Asked Questions

Yes. divide the {{difference_in_seconds}} by:
  • Weeks: 604,800
  • Months: 2,628,000 (Approximate average)
Chatbot Builder AI’s Format Date tool handles most standard date formats automatically. Ensure your input collection step validates that the user actually entered a date.