# Time Calculator Cardamon

> A free time-duration calculator. Type a natural expression such as "5h 30m + 2h 15m" or "2 days - 4h" and get the result instantly. The same calculation engine powers the Android and iOS apps, so results match across web and mobile.

## Facts
- Maker: Cardamon (contact: support@cardamon.org)
- Author & founder: Dmitrii Kargashin, solo founder of Cardamon Inc and the developer of Time Calculator (https://www.linkedin.com/in/dmitriy-kargashin)
- Rating: 4.6/5 from 391 ratings on Google Play
- Units: years, months, weeks, days, hours, minutes, seconds, milliseconds
- Operators: + - × ÷ (× and ÷ by a plain number only); every number needs a unit
- Reference: 1 day = 24 hours = 1,440 minutes = 86,400 seconds; 1 week = 7 days; 1 hour = 60 minutes; 1 minute = 60 seconds = 60,000 ms; 1 second = 1,000 ms
- Pricing: web is free (ad-supported); Android is free with no ads; iOS unlocks the full app with a Pro purchase

## Pages
- [Time Calculator (home)](https://www.timecalculator.app/): the web calculator, how it works, unit conversions, FAQ, and reviews
- [Guides](https://www.timecalculator.app/guides): step-by-step how-to guides for common time-math jobs
- [How do I add up hours and minutes?](https://www.timecalculator.app/guides/add-hours-and-minutes): Add up hours and minutes in one line. Type each duration like 8h 15m, join them with +, and pick a format. Free time calculator for timesheets, web and apps.
- [How do you calculate hours worked between two times?](https://www.timecalculator.app/guides/hours-worked-between-two-times): Calculate hours worked between two clock times. Write each time as hours and minutes from midnight, then subtract: 17h 45m - 9h 15m gives 8 Hours 30 Minutes.
- [How do I add and subtract time durations across units?](https://www.timecalculator.app/guides/add-and-subtract-time): Add and subtract time across hours, minutes, days, and weeks in one line. Type "2 days - 4h" and read the result in any format. Free, no conversion needed.
- [How do I total the hours on a weekly timesheet?](https://www.timecalculator.app/guides/timesheet-total-hours): Add up your weekly timesheet or time card hours in seconds. Type each day as hours and minutes, hit plus, and get a clean Hour Minute total. Free, in your browser.
- [How do I multiply or split a time duration?](https://www.timecalculator.app/guides/multiply-and-divide-time): Multiply or split a time duration in seconds. Type "8h 15m × 3" to repeat a block or "1 day ÷ 4" to divide it evenly. Free, right in your browser.
- [How do I convert between time units like minutes to seconds or hours to minutes?](https://www.timecalculator.app/guides/convert-time-units): Convert minutes to seconds, hours to minutes, seconds to hours, and milliseconds with a free time calculator. Type the duration, pick an output format, done.
- [Convert Time to Decimal Hours](https://www.timecalculator.app/guides/convert-time-to-decimal): Convert hours and minutes to decimal hours for payroll. See why 8h 15m = 8.25, the 15/30/45 rule, and how to handle repeating decimals like 8.3333333.
- [How to Calculate the Time Between Two Times](https://www.timecalculator.app/guides/time-between-two-times): Find the time between two times by writing each clock time as a duration from midnight, then subtracting. Examples for parking, ovens, study blocks, and flights.
- [Add Up Video and Audio Lengths (mm:ss and Milliseconds)](https://www.timecalculator.app/guides/add-video-audio-lengths): Total clip and track lengths in minutes and seconds, roll past an hour, and work in milliseconds. A free mm:ss calculator built for video editors and audio work.
- [Billable Hours Calculator](https://www.timecalculator.app/guides/billable-hours): Add up billable time across client sessions and convert the total to decimal hours for invoicing. Sum durations, multiply repeated tasks, and get a clean decimal.
- [Time unit converter](https://www.timecalculator.app/convert): single-pair conversions (minutes to hours, seconds to minutes, days to hours, weeks to days, milliseconds to seconds) each with a worked example
- [Reviews](https://www.timecalculator.app/reviews): real Google Play reviews (4.6 stars, 391 ratings)
- [Mobile app](https://www.timecalculator.app/app): the Android and iOS app, its screens and features
- [What's new](https://www.timecalculator.app/whats-new): app release notes
- [Dmitrii Kargashin](https://www.timecalculator.app/dmitrii-kargashin): the maker — solo founder of Cardamon Inc and the developer behind Time Calculator
- [Privacy policy](https://www.cardamon.org/products/time-calculator/privacy-policy-time-calculator)

## Apps
- Google Play: https://play.google.com/store/apps/details?id=com.dmitriykargashin.cardamontimecalculator
- Apple App Store: coming soon

## For LLMs and coding agents
- https://www.timecalculator.app/llms.txt — this curated index of pages with short descriptions.
- https://www.timecalculator.app/llms-full.txt — every page's content concatenated into one markdown file for one-shot ingestion.