Utilities
Processed locally in your browser

Timezone / Date Math Calculator

Convert times across time zones, plan meetings, calculate business-day offsets and SLA deadlines, parse ISO durations, and inspect date ranges — locally in your browser.

Tool workspace

  • Translate release, incident, or meeting times across multiple IANA time zones at once.
  • Apply day, week, month, hour, minute, second, or business-day offsets — with month-end and DST-aware warnings.
  • Compute SLA deadlines using business hours, weekends, and a custom holiday list.
  • Parse ISO 8601 / friendly durations, inspect date ranges, and export Markdown / CSV / JSON / .ics.
  • Share results: Generate a secure link to share your current input and results with teammates — nothing is uploaded to any server.

One tool for wall-clock conversions, multi-zone planning, business-day math, SLA deadlines, and ISO duration parsing.

Timezone conversion

Naive values such as 2026-04-04 15:30 are interpreted in the source time zone you provide. Trailing Z or an offset like +05:30 overrides the source zone.

Output

How to use the Timezone & Date Math Calculator

One calculator for the date and time problems engineers hit every week: convert timestamps across time zones, plan release / incident / on-call windows, do calendar or fixed-duration date math, compute SLA deadlines that respect business hours and holidays, parse ISO 8601 durations like P3DT4H30M, and produce ready-to-paste timezone tables for Slack or Teams. Runs locally in your browser using the IANA timezone database that ships with modern browsers.

What it does

When to use it

How to use it

  1. Convert: enter source date/time and source/target zones. The same instant is shown in both.
  2. Multi-Zone: pin several zones for a single moment.
  3. Date math: pick the unit and offset; toggle calendar vs fixed-duration semantics.
  4. Business / SLA: set weekend rule, business hours, holiday list, then compute the deadline.
  5. Duration: paste an ISO 8601 string or human-friendly duration to break it down.
  6. Date range: enter start and end and read the difference in multiple units.
  7. Calendar: download .ics or open Google Calendar from the computed time.

Tips & pitfalls

FAQ

Runs locally in your browser using the IANA timezone database. No uploads. Holidays you configure stay in your browser.

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