Z

Date Calculator — Add, Subtract & Diff Dates (Business Days)

Add or subtract years, months, weeks, days, hours and minutes to a date — or compute the difference between two dates with business-day count.

Free No signup Client-side Privacy friendly

Values may be negative to subtract.

Result

Pick a start date to begin.

Duration

Pick both dates to compare.

How to use

  1. 1 Pick a mode — Add / subtract a duration from a date, or compute the Difference between two dates.
  2. 2 In Add mode, type any positive or negative number into the Years / Months / Weeks / Days / Hours / Minutes fields.
  3. 3 In Difference mode, pick both dates and times. Calendar breakdown plus totals appear instantly.
  4. 4 Copy the ISO result with the Copy ISO button (Add mode).

Why use this tool

  • Day-of-month clamp — adding 1 month to Jan 31 gives Feb 28 or 29, not "Feb 31".
  • Calendar Y/M/D breakdown alongside totals — both views matter for different jobs.
  • Business-days counter excludes weekends (Mon–Fri).
  • No timezone surprises — calculations stay in your local zone.

Frequently asked questions

Does the business-days count exclude holidays?

No, it only excludes Saturdays and Sundays. Public holidays vary by country so we don't hard-code them — subtract holidays manually if needed.

Why does "1 year" not always equal 365 days?

Calendar arithmetic snaps to the same month / day, so the day count can be 365 or 366 depending on leap years. The Total days field shows the exact figure.

Need to convert the result into another timezone?

Use our Timezone Converter — paste the ISO output, then pick source and target zones.

How do I add hours across daylight saving?

Add Hours uses calendar time. Crossing a DST boundary will appear to "jump" by an hour. For instant arithmetic, use the Unix Timestamp Converter.

Summary

Date Calculator is a free creator utility by Zerethon Tools. Add or subtract years, months, weeks, days, hours and minutes to a date — or compute the difference between two dates with business-day count. Runs entirely in the browser — no signup, no upload.

Category
Creator
Pricing
Free
Privacy
Browser-based
Signup
Not required

Privacy

Your data never leaves your browser unless explicitly stated. Date Calculator runs entirely client-side — no server upload, no logging, no tracking of your input.

Related tools

YouTube Thumbnail Downloader

Download YouTube thumbnails in all available resolutions. Just paste a video URL.

Open tool

Open Graph Preview

Test how your URL appears when shared on social media. Preview Facebook, Twitter, LinkedIn, and Slack cards.

Open tool

Word & Character Counter

Count words, characters, sentences, and paragraphs. Reading time, speaking time, and top keywords — instant.

Open tool

Lorem Ipsum Generator

Generate Lorem Ipsum placeholder text — by paragraphs, sentences, or words. Optional HTML wrapping.

Open tool

Build, share, and grow on Zerethon Social

Free signup. Earn points, collect achievements, and connect with creators worldwide.

Try Zerethon free