# Date & Time Calculator

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

Free date and time calculator: difference between two dates in years, months, days, weeks and hours, business day counting, and add or subtract days, months and years from any date. Instant, private, in your browser.

- **Canonical:** https://www.ailovekit.com/calculators/date-time-calculator/
- **Category:** Calculator
- **Processing:** Runs entirely in your browser. Files are never uploaded to AiLoveKit servers.

## How It Calculates

- **Formula:** duration = end date - start date; business days count Mon-Fri in range

All calculation runs locally in your browser; results update as you type and include the substituted working.

## 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](https://www.ailovekit.com/calculators/tax-calculator/) for invoice totals and the [Unit Converter](https://www.ailovekit.com/calculators/unit-converter/) for measurements.

## Frequently Asked Questions

**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.

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Source: https://www.ailovekit.com/calculators/date-time-calculator/
Part of AiLoveKit: https://www.ailovekit.com/
Machine-readable index: https://www.ailovekit.com/llms.txt