Date Math Kit
A step-by-step workflow for deadlines, scheduling, and quick offsets. Everything runs locally in your browser.
Workflow
- 1) Pick the unit that matches the decision
Use Days From Today or Weeks From Today when you care about the date. Use Hours From Now or Minutes From Now when you need an exact time.
- 2) For deadlines, decide if counting is inclusive
The day/week tools include an option like “Include today”. This is the classic confusion behind “due in 7 days” vs “due 7 days after today”. Toggle it once and stick to the same convention across your docs or emails.
- 3) For reminders and ETAs, compute the exact local time
Use the hours/minutes tools to calculate an end time for meetings, breaks, cooking, or delivery ETAs. Results are based on your device clock and timezone.
- 4) sanity-check with a second unit
If something feels off, recompute using a different unit (for example, “90 minutes from now” vs “1.5 hours from now”) to confirm you didn't mix conventions.
Common pitfalls
- Inclusive counting: “Include today” changes what “1 day” means.
- Timezone assumptions: results are in your device timezone, not a server timezone.
- DST boundaries: hour-based calculations may cross daylight-saving time changes.
- Rounding: “hours” supports decimals; “minutes” is easiest for exact short offsets.