How does this calculator handle leap years?

The calculator accurately accounts for leap years when calculating the time difference between two dates. It uses the JavaScript Date object, which is based on the Gregorian calendar and correctly handles the extra day in a leap year (February 29th).

Can I count down to an event in a different time zone?

The calculator operates based on your device's local time zone. When you input a date and time, it's assumed to be in your current time zone. For events in other time zones, you should first convert the event's time to your local time and then enter that into the calculator.

What's the difference between 'Countdown to Date' and 'Countdown for Duration'?

'Countdown to Date' calculates the time remaining between now and a specific future point in time (e.g., New Year's Day). 'Countdown for Duration' simply starts a timer for a length of time you specify (e.g., 25 minutes).

Does the countdown update in real-time?

Yes. Once you start the countdown, the display will update every second to show the time remaining.

Can I save or share my countdown?

This tool is a client-side calculator, meaning it runs in your browser. It does not save your countdowns on a server. If you close the page, the timer will be lost. To share, you can simply share the URL of this calculator page.

What is the 'Unix timestamp' mentioned in the formula?

A Unix timestamp is the total number of milliseconds that have elapsed since midnight (00:00:00 UTC) on January 1, 1970. It's a universal standard used by computer systems to represent a specific point in time.

Countdown Calculator - Calculate Time Remaining

Audit: Complete

Formula (LaTeX) + variables + units

This section shows the formulas used by the calculator engine, plus variable definitions and units.

Formula (extracted LaTeX)

\[\Delta t_{\text{ms}} = T_{end} - T_{start}\]

\Delta t_{\text{ms}} = T_{end} - T_{start}

Formula (extracted LaTeX)

\[\text{TotalSeconds} = \lfloor \frac{\Delta t_{\text{ms}}}{1000} \rfloor\]

\text{TotalSeconds} = \lfloor \frac{\Delta t_{\text{ms}}}{1000} \rfloor

Formula (extracted LaTeX)

\[\text{TotalMinutes} = \lfloor \frac{\text{TotalSeconds}}{60} \rfloor\]

\text{TotalMinutes} = \lfloor \frac{\text{TotalSeconds}}{60} \rfloor

Formula (extracted LaTeX)

\[\text{TotalHours} = \lfloor \frac{\text{TotalMinutes}}{60} \rfloor\]

\text{TotalHours} = \lfloor \frac{\text{TotalMinutes}}{60} \rfloor

Formula (extracted LaTeX)

\[\text{TotalDays} = \lfloor \frac{\text{TotalHours}}{24} \rfloor\]

\text{TotalDays} = \lfloor \frac{\text{TotalHours}}{24} \rfloor

Formula (extracted text)

$ \Delta t_{\text{ms}} = T_{end} - T_{start} $

Formula (extracted text)

$ \text{TotalSeconds} = \lfloor \frac{\Delta t_{\text{ms}}}{1000} \rfloor $ $ \text{TotalMinutes} = \lfloor \frac{\text{TotalSeconds}}{60} \rfloor $ $ \text{TotalHours} = \lfloor \frac{\text{TotalMinutes}}{60} \rfloor $ $ \text{TotalDays} = \lfloor \frac{\text{TotalHours}}{24} \rfloor $

Variables and units

No variables provided in audit spec.

Sources (authoritative):

iso.org/standard/40874.html — iso.org · Accessed 2026-01-19
https://www.iso.org/standard/40874.html
Home — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/
Lifestyle Everyday — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/lifestyle-everyday
Time and Date — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/subcategories/time-date
Time Duration Calculator — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/time-duration-calculator
Date Calculator — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/date-calculator
Age Calculator — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/age-calculator

Changelog

Version: 0.1.0-draft
Last code update: 2026-01-19

0.1.0-draft · 2026-01-19

Initial audit spec draft generated from HTML extraction (review required).
Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
Confirm sources are authoritative and relevant to the calculator methodology.

Verified by Ugo Candido on 2026-01-19
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