Everyday date & time calculations, made clear.
Count days, add or subtract dates, calculate business days, combine time durations, compare time zones and more — with fast browser-based tools that work beautifully on mobile.
Choose a calculator
Dedicated tools for the exact question you are trying to answer.
Date Calculator
Add or subtract days, weeks, months and years from any date.
Open calculator →Days Between Dates
Count exact days, weeks and hours between two dates.
Count days →Date Difference
See the difference as years, months and days plus exact totals.
Compare dates →Business Days
Count or add workdays with custom weekends and holiday exclusions.
Calculate workdays →Time Calculator
Add and subtract multiple hours, minutes and seconds.
Calculate time →Time Duration
Find the hours and minutes between two clock times, even overnight.
Find duration →Date & Time Difference
Compare full timestamps across time zones with DST-aware math.
Compare timestamps →Hours & Minutes
Convert hours and minutes to decimal hours and back again.
Convert time →Week Number
Find the ISO week number and week-year for any date.
Find week →Weekday Calculator
Find which day of the week any calendar date falls on.
Find weekday →Designed to be more useful than a basic calculator
DateTimeWise combines fast answers with the details people usually need next.
No account, server round-trip or waiting for a result page.
Calendar views make long date ranges easier to understand.
Compare timestamps using browser-supported IANA time zones.
Choose weekend days and add your own non-working dates.
Calculator inputs can be reflected in the URL where useful.
Keep useful calculations on your own device with local storage.
Turn results into clean, branded text or a printable summary.
Core calculator inputs are processed locally in your browser.
Start with the question you have now.
Need to count calendar days, working days, or elapsed time? Pick the closest tool and DateTimeWise will show the answer plus useful related totals.
Count days between datesAbout DateTimeWise calculators
DateTimeWise is a focused collection of date and time utilities for everyday planning, project deadlines, invoices, schedules, study, travel coordination and general calendar math. Instead of making one overloaded form handle every possible task, we provide dedicated pages for distinct intents such as adding days to a date, counting business days and finding elapsed clock time.
For transparency, our calculation guide explains endpoint inclusion, calendar differences, ISO weeks, public-holiday presets and timezone limitations. Calculator results are intended for general informational use; important legal, financial, payroll, medical or compliance deadlines should be verified with the appropriate authoritative source.