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CyberJerry Seconds Calculators 2.5.0001
These forms launch simple calculator windows to determine the number of seconds elapsed between two dates and times.

System time check  
 

OK. Now fill out and submit any of the following calculation forms:

1. CountUp 
How many seconds have elapsed since a given (past) date/time?   (Examples: Someone's age in seconds; Negative countdown)
Specify start (past) date and time:
MM/DD/YYYY: //
  HH:MM:SS: ::
Timezone:
 
Title for this calculation (optional):
 
 
2. CountDown 
(Inverse of #1) - How many seconds away is a given (future) date/time?   (Example: Seconds until Christmas)
Specify end (future) date and time:
MM/DD/YYYY: //
  HH:MM:SS: ::
Timezone:
 
Title for this calculation (optional):
 
 
3. Past Interval 
Calculate past date/time a given number of seconds ago.   (Example: What date/time was a billion seconds ago?)
Specify past time interval:
   Seconds:

Title for this calculation (optional):

 
4. Future Interval 
(Inverse of #3) - Calculate future date/time a given number of seconds from now.   (Example: What date/time is a billion seconds from now?)
Specify future time interval:
   Seconds:

Title for this calculation (optional):

 
5. Forward Interval 
Calculate date/time a specified number of seconds after a given date/time.   (Example: When will so-and-so be a billion seconds old?)
Specify start date and time:
MM/DD/YYYY: //
  HH:MM:SS: ::
Timezone:
Specify time interval:
   Seconds:

Title for this calculation (optional):
 
 
6. Backward Interval 
(Inverse of #5) - Calculate date/time a specified number of seconds before a given date/time.   (Example: What date/time was a billion seconds before the Twin Towers attack?)
Specify end date and time:
MM/DD/YYYY: //
  HH:MM:SS: ::
Timezone:
Specify time interval:
   Seconds:

Title for this calculation (optional):
 
 
7. Difference 
How many seconds between two given dates/times.   (Example: Difference, in seconds, between two persons' ages)
Specify start date and time:
MM/DD/YYYY: //
  HH:MM:SS: ::
Timezone:
 
Specify end date and time:
MM/DD/YYYY: //
  HH:MM:SS: ::
Timezone:
 
Title for this calculation (optional):
 
Contents:

System time check Verify your computer's time and timezone settings.
Calc 1 - CountUp How many seconds have elapsed since a given (past) date/time?
Calc 2 - CountDown How many seconds away is a given (future) date/time?
Calc 3 - Past Interval Calculate past date/time a given number of seconds ago.
Calc 4 - Future Interval Calculate future date/time a given number of seconds from now.
Calc 5 - Forward Interval Calculate date/time a specified number of seconds after a given date/time.
Calc 6 - Backward Interval Calculate date/time a specified number of seconds before a given date/time.
Calc 7 - Difference How many seconds between two given dates/times.

Notes:

Billionth birthsecond note:
For billionth birthsecond observance, first use the 5. Forward Interval calculation form below to determine when your billionth birthsecond will occur, then run the 1. CountUp calculation at that time to watch your personal odometer roll over.

General notes  (Includes development history)

Timezone / Daylight Saving notes 

Browser / javascript notes 

End Notes

Feedback:

Find a bug? Have a comment or suggestion to make? Let me hear from you:

Blogger site comment  (The comments page of my blog post related to this Seconds Calculator.)

Contact page 


End Notes

Author: Jerry DePyper
Spanish consultant: Isaac Abraham Martínez Rizo
Resources: html 4.01, css, javascript, php
Current release: 2.5.0001
Revision date: Jun 08, 2025
Use the Contact Page to report bugs, comments, suggestions, etc.