How is the year, month, day breakdown counted?

The same way people count age or tenure: full calendar years first, then full months, then remaining days. Between 15 Jan and 3 Mar you get 1 month, 16 days.

Do business days include public holidays?

No. Business days are Monday to Friday only. Deduct any public holidays that fall in your range for an exact working-day count.

What happens when I add a month to January 31?

The calendar normalizes overflow: since 31 February does not exist, adding one month to 31 January lands on 3 March (2 March in leap years). If you need end-of-month behavior, calculate from the 1st of the month instead.

Which time zone is used?

Your local calendar. Date-only math has no time zone ambiguity because both dates are treated as midnight in your local zone.

Date & Time Calculator - Differences, Durations & Business Days

Find the exact difference between two dates in years, months and days, count business days, or add and subtract durations from any date.

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Count Days the Way Calendars Really Work

Deadlines, notice periods, delivery windows and ages all hinge on calendar math that spreadsheets get subtly wrong. AiLoveKit's date & time calculator gives you the human breakdown (years, months, days) plus the totals you can act on: total days, weeks, hours and business days with weekends excluded.

Two Modes

Difference between dates - full breakdown, totals and weekday counts in one click.
Add or subtract days - project a date forward or back by years, months and days, with the resulting weekday shown.

Everything runs locally in your browser; no dates are ever uploaded.

Related: the Tax Calculator for invoice totals and the Unit Converter for measurements.