Date Time Calculator to Add or Subtract Time Spans To/From Dates

Date Time Calculator Sign

This date and time calculator will subtract or add days, weeks, months, years, hours, minutes, and seconds from or to the date and time you select.

Note that if you would like to find the number of days between two dates, or the number of days left until a certain date, please visit the Date Difference Calculator.

Or, if you would like to calculate the number of working days between two dates, or calculate the date after adding or subtracting a number of working days, please visit the Business Days Calculator.

Number of Uses Only Limited By Your Imagination

One user reported he uses the calculator to know when to start his 3D printing jobs, so they are done at the desired date/time (subtracts the 3D print time from date/time he wants it done by).

Want to find out what the date will be when a 30, 60, 90, 120, 180, 365, or 500-day event is set to occur?

Simply select today as the starting date, now as the starting time, add as the operation to perform, and enter the desired number of days to add to the date, and the calculator will tell you the resulting date -- along with the time and day of the week.

Or, do you want to know what the date was a given number of days, weeks, months, or years ago? No problem. Just select today as the starting date, select subtract from the operation menu, enter the number of time spans to subtract, and click the "Calculate Date" button!

Here are just a few of the many questions the time date calculator can help you to answer:

  • On what day will my 90-day warranty expire?
  • On what day is my 60-day note due?
  • What day does my 30-day free trial expire?
  • What day will it be 100 days from today?
  • What day will it be 500 days from now?
  • If we met on this date, on what day will our 6-week anniversary fall?
Read more ...

Also on this page:

Date Time Calculator

Add or subtract spans of time to or from a date and time of your choosing.

Special Instructions

Learn More

Selected Data Record:

A Data Record is a set of calculator entries that are stored in your web browser's Local Storage. If a Data Record is currently selected in the "Data" tab, this line will list the name you gave to that data record. If no data record is selected, or you have no entries stored for this calculator, the line will display "None".

DataData recordData recordSelected data record: None

Starting date:

Select the month and day and enter the 4-digit year of the date you want to add to or subtract from. Note that the year must be greater than 0 and less than 4000.


Starting time:

If you want to set a starting time (optional), change the hour, minute, and second selection to the desired time (or tap the "Begin", "Noon", or "Now" buttons to set a general time of day). Changing the selection back and forth from the Now option to another option will update the time setting to the new Now time.

Operation:Operation:Operation to perform:Choose operation to perform:

Add or subtract time span:

Select Add or Subtract.

Time spans to add or subtract:

Time span to add or subtract:

Enter the number of each time unit you would liked added to or subtracted from the starting date. Note that the results will differ between adding or subtracting 1 year or 1 month versus adding or subtracting 365 days or 30 days. This is due to effects of daylight savings time, leap years, and calendar months having different number of days.

Result date and time:

Result date and time:

This is the calculated date and time after adding or subtracting the entered date and time units. Note that years and months are added or subtracted first, and then the weeks, days, hours, minutes, and seconds are added or subtracted after that.

If you would like to save the current entries to the secure online database, tap or click on the Data tab, select "New Data Record", give the data record a name, then tap or click the Save button. To save changes to previously saved entries, simply tap the Save button. Please select and "Clear" any data records you no longer need.

Help and Tools


Bonus date time calculators.

The following quick-answer calculators will perform the work of many sought-after calculators: 48-hour calculator, 72-hour calculator, 60 days calculator, 90-day calculator, 120 days calculator, etc.

Add Hours to Current Time

Example use: When is 72 hours from now? Enter 72 in the calculator below and click the Calculate Hours From Now button.

Hours From Now Calculator
When ishours from now?
Future time and date will appear here.

Subtract Hours From Current Time

Example use: What time was it 18 hours ago from now? Enter 18 in the calculator below and click the Calculate Hours Ago button.

Hours Ago Calculator
When washours ago?
Past time and date will appear here.

Add Days to Today

Example use: When is 90 days from today? Enter 90 in the calculator below and click the Calculate Days From Now button.

Days From Now Calculator
When isdays from now?
Future time and date will appear here.

Subtract Days From Today

Example use: What day is today minus 90 days? Enter 90 in the calculator below and click the Calculate Days Ago button.

Days Ago Calculator
When wasdays ago?
Past time and date will appear here.

Adjust Calculator Width:

Move the slider to left and right to adjust the calculator width. Note that the Help and Tools panel will be hidden when the calculator is too wide to fit both on the screen. Moving the slider to the left will bring the instructions and tools panel back into view.

Also note that some calculators will reformat to accommodate the screen size as you make the calculator wider or narrower. If the calculator is narrow, columns of entry rows will be converted to a vertical entry form, whereas a wider calculator will display columns of entry rows, and the entry fields will be smaller in size ... since they will not need to be "thumb friendly".

Show/Hide Popup Keypads:

Select Show or Hide to show or hide the popup keypad icons located next to numeric entry fields. These are generally only needed for mobile devices that don't have decimal points in their numeric keypads. So if you are on a desktop, you may find the calculator to be more user-friendly and less cluttered without them.

Stick/Unstick Tools:

Select Stick or Unstick to stick or unstick the help and tools panel. Selecting "Stick" will keep the panel in view while scrolling the calculator vertically. If you find that annoying, select "Unstick" to keep the panel in a stationary position.

If the tools panel becomes "Unstuck" on its own, try clicking "Unstick" and then "Stick" to re-stick the panel.