Date Add or Subtract Calculator - Add Days to a Date

Add or Subtract Days From a Date

The Date Add/Subtract calculator finds a new date by adding or subtracting time from any starting date. Pick a date, enter how many years, months, weeks, or days to move, and the result appears instantly with the weekday already worked out.

Use it to answer everyday date questions — what date will it be in 30 days, when a 6-month contract expires, or which day falls 90 days from today. You can move forward with Add or backward with Subtract, combine several units at once, and read the full date span on a built-in calendar.

Private by design: every calculation runs in your browser. Your dates and settings are saved only on your own device and never uploaded to a server.

How to Use the Date Add/Subtract Calculator

Choose a start date

Click the date field to open the picker and select your starting date, or click Today to set it to today instantly.

Pick Add or Subtract

Select Add to move forward in time or Subtract to move backward. The active option is highlighted.

Enter the duration

Fill in any combination of Years, Months, Weeks, and Days — for example 1 year and 6 months, or just 30 days. Or tap a Quick preset (7d, 14d, 30d, 60d, 90d, 180d, 365d) to fill the days field in one click.

Read and copy the result

The new date appears with its weekday, a difference breakdown, extra date info, and a calendar view. Click Copy Result to copy a formatted summary to your clipboard.

Features

Add or Subtract Any Duration

Combine years, months, weeks, and days in a single calculation. Edge cases like month-end dates and leap years are handled automatically.

Quick Preset Buttons

One tap on 7, 14, 30, 60, 90, 180, or 365 days fills the duration and calculates the result for the most common spans.

Real-Time Calculation

Results update the moment you type or change any input — there is no Calculate button to press.

Detailed Result Display

See the result date in a readable format with its weekday and a clear summary of what was added or subtracted.

Difference Breakdown

View the total days, weeks (with remaining days), hours, and business days between the start and result dates.

Result Date Information

Get the day of the year, ISO week number, calendar quarter (Q1-Q4), and whether the result year is a leap year.

Visual Calendar View

A scrollable calendar shows every month in the range with the start date, result date, in-range days, and today all color-coded.

Copy to Clipboard

Copy a formatted summary — start date, operation, result date, total days, and business days — to paste anywhere.

Persistent Settings

Your start date, operation mode, and duration values are saved in your browser and restored when you return.

Frequently Asked Questions

How do I add days to a date?

Pick a start date, leave the operation on Add, and type the number of days in the Days field — or tap a quick preset like 30d. The new date and its weekday appear instantly.

How do I subtract days from a date?

Switch the operation to Subtract, then enter the duration. For example, subtracting 30 days from March 1 gives January 30. Subtract moves the date backward through time.

What date will it be in 30 or 90 days?

Click Today to set the start date, keep the operation on Add, then tap the 30d or 90d preset. The result shows the exact date and weekday that many days from today.

Can I add weeks, months, and years too?

Yes. Fill in any combination of the four fields. The calculator applies them in order — years first, then months, then weeks and days — so 1 year 6 months works as expected.

Does it handle leap years and month lengths?

Yes. Adding 1 month to January 31 lands on the last valid day of February — February 28 in a normal year, February 29 in a leap year. This is standard date arithmetic.

What counts as a business day?

Business days are weekdays, Monday through Friday, with Saturday and Sunday excluded. The Difference card shows how many working days fall between the start and result dates.

What do Day of Year and Week Number mean?

Day of Year is the day's position in its year (January 1 is day 1, December 31 is day 365 or 366). Week Number follows the ISO standard, where weeks start on Monday and week 1 contains the first Thursday of January, ranging from 1 to 53.

Is there a maximum duration I can enter?

The fields accept up to 999 years, 999 months, 999 weeks, and 9999 days. The calendar view displays up to 36 months of the date range at once.

Are my dates saved and private?

Your start date, operation, and duration values are saved in your browser's local storage and restored on your next visit. Every calculation runs locally — nothing is uploaded or stored on any server.