Finance & Money
FinanceConversion
Construction & Other
ConstructionEcologyOther
MathFinanceConversionHealthConstructionPhysicsChemistryBiologyEcologyEveryday LifeFoodSportsStatisticsOther

Date Calculator

Whether you’re counting days between events or shifting deadlines by business days, this calculator handles every date math scenario.

Date Range Summary

Start

Saturday, May 23, 2026

End

Saturday, May 23, 2026

Total days: 1
Business days: 0
Weekend days: 1
Weeks: 0.14
Approx months: 0.03
Approx years: 0.00
Tip: total days count includes both the start and end date. Subtract one if you want exclusive range (start-exclusive end-inclusive).

Instructions

1

Choose your mode

Pick “Count Days” to find the duration between two dates, or “Add/Subtract” to shift a single date by days.

2

Enter relevant dates

For durations, specify start and end. For shifting, select the base date and days to move. Toggle “business days” to skip weekends automatically.

3

Review results

See total days, business days, and approximate weeks/months (duration) or the resulting date with weekend adjustments (add/subtract).

Formula

Total Days = (End − Start) + 1

Business Days = Count of weekdays between Start and End

Approx Months = Total Days ÷ 30.4375

Example: Adding 30 business days to 2025-11-09 yields simply 30 calendar days ahead depending on the setting.

Why Date Math Matters

Accurate date calculations keep projects on track, prevent missed deadlines, and help coordinate across teams and time zones.

  • Plan contract milestones or invoice due dates without manually counting days.
  • Calculate retention periods, warranties, or compliance dates with precision.
  • Schedule events and marketing campaigns by aligning to business days.
  • Avoid errors caused by leap years, month lengths, or weekend overlaps.

Common Questions

Does this include holidays?

Holidays are not excluded automatically. Pair this tool with a holiday list if you need true business days for a specific country.

Are start and end dates inclusive?

Duration mode counts inclusively. If you need an exclusive range, subtract one day or adjust the inputs.

What about time zones?

Dates use the local timezone of your browser. Align on a reference calendar date when collaborating across regions.

Can I shift by months instead of days?

This calculator focuses on day-based math. For month shifts, step month-by-month or use a calendar tool with month arithmetic.