Date Difference Calculator | Days Between Dates

Quick Start Guide

  1. Select mode: Choose "Find Duration" to calculate time between dates, or "Add/Subtract Time" to add or subtract time from a date.
  2. Enter dates: Select start and end dates, or use presets like Today and Next Week.
  3. Choose calculation type: Select All Days or Working Days (excludes weekends).
  4. View results: See a breakdown including years, months, days, and weeks.
  5. Use presets: Quick access to common dates for faster calculations.
  6. Export results: Save calculations to JSON, CSV, or PDF.

Understanding Date Math

Duration / Business Days / Add-Subtract

These are three genuinely different calculations, not display variants of one number: Duration measures a calendar span between two dates, Business Days counts weekdays (and optionally holidays) in that span, and Add/Subtract projects a new date from a base date plus or minus a duration.

Exclusive day counting

Total Days uses the same convention as plain subtraction (end date minus start date) — Jan 1 to Jan 2 is 1 day, not 2. The years/months/days breakdown always agrees with Total Days because both use this same exclusive convention.

Month-end overflow in Add/Subtract

Adding months doesn't clamp to a shorter target month — adding 1 month to January 31 rolls over into March 2 or 3 (whichever February has 28 or 29 days that year), rather than landing on February's last day.

What this calculator does not cover

Holiday exclusion (in the Working Days settings) covers standard U.S. federal holidays plus any custom dates you add — it does not know about company-specific closures or other countries' holiday calendars unless you add them manually. For duration arithmetic within a single day, see the Time Calculator.

Features

Date Range Analysis: Get detailed date-range breakdowns including total days, weeks, hours, and year-month-day split.

Business Days Calculator: Calculate working days excluding weekends and optionally holidays.

Date Presets: Quick access to common dates like Today, Tomorrow, Next Week, and End of Month.

Export Data: Export date calculations to JSON, CSV, or PDF format.

Common Use Cases

Project Timeline Planning: Calculate working days between milestones, plan deadlines excluding weekends, and track project duration.

Business Day Calculations: Determine contract delivery dates, processing time estimation, and payroll cycles.

Age and Duration: Track time since past events, subscription duration, and get a detailed age breakdown.

Event Planning: Count down to upcoming events, schedule recurring meetings, and plan booking timelines.

Frequently Asked Questions

Select 'Find Duration' mode, enter your start and end dates, and choose whether to include weekends. The calculator shows the duration in years, months, days, weeks, and hours. Use date presets like 'Today' or 'Next Week' for quick selections.
'All Days' counts every day including weekends. 'Working Days' excludes weekends (Saturday and Sunday) and optionally holidays, giving you the number of business days between dates. This is useful for project timelines and contract calculations.
Total Days uses exclusive counting — the same as subtracting the start date from the end date — so Jan 1 to Jan 2 counts as 1 day, not 2. The years/months/days breakdown uses the same convention, so the two figures always agree.
Select 'Add/Subtract Time' mode, enter your start date, and specify how many years, months, and days to add or subtract. The calculator shows the resulting date. Useful for calculating deadlines, expiration dates, or future events.
Yes. When using 'Working Days' mode, you can optionally exclude holidays. The calculator automatically excludes weekends and can be configured to exclude specific holidays for more accurate business day calculations.
Quick date presets include 'Today', 'Tomorrow', 'Next Week', 'End of Month', and more. These presets speed up date selection for common calculations. Click on any preset to automatically set that date.

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