CalendarMath

What do you want to calculate?

Quick, no-login tools for dates, time zones, and meeting planning.

Tip: Press / anywhere to open the tool search.

Date Math

Simple answers for everyday date questions.

Days Between Dates
Calculate days between two dates with inclusive/exclusive options, plus weeks, months (approx), and years (approx).
Add / Subtract Days From Date
Add or subtract a number of days from a date. Optionally exclude weekends and US federal holidays.

Time Zones & Meetings

DST-aware conversions and overlap planning.

Time Zone Converter
Convert a date and time between time zones (DST-aware) and copy results instantly.
Meeting Time Overlap Finder
Find meeting times across 2–4 time zones based on each location’s working hours.

Why CalendarMath?

Designed for speed and clarity. No accounts. No clutter.

Inputs are big, results show instantly, and advanced options are tucked away so you can stay focused.

Privacy-friendly by default

No logins, no saved profiles.

“Recent tools” is stored locally on your device only (localStorage).
Internal links
Tools indexDays Between DatesAdd / Subtract Days From DateTime Zone ConverterMeeting Time Overlap Finderhttps://calendarmath.com