Date & TimeUpdated 2026-05-20

Date Add/Subtract Calculator

Add or subtract days and months from a date.

Start dateDays to addMonths to add

Start using it Formula and examples

Enter assumptions

Start with the inputs that actually change the result.

OUT

Check the result

The live panel updates the main number and supporting outputs.

Open context only when needed

Formula notes, FAQ, and related guides stay below the tool.

Inputs

Date Add/Subtract Calculator

Results update as you type.

Live result

Result date

2026-05-12

Total days changed

Scenario compare

Save scenario A, change a few inputs, then save scenario B.

Scenario A

Not saved yet

Scenario B

Not saved yet

Quick check

Change one or two inputs to compare a second scenario before using the number.

Need more detail?

Formula, examples, and FAQ stay tucked away until you need them.

FXFormula ExplanationThe core logic behind the numbers on this page.+

Our date calculator uses a UTC date calculation to ensure accurate results. It first adds or subtracts calendar months, then days, to provide a precise date difference. This approach avoids time-zone drift and ensures reliable calculations. The calculator also considers leap years and month lengths to provide a comprehensive date difference.

USEHow to UseA short path from input to result.+

Enter the requested inputs.
Keep any editable rule or rate fields aligned with your situation.
Review the result and notes before using the estimate.

EXExamplesReference scenarios to sanity-check your inputs.+

Adjust the defaults to match your scenario, then calculate the estimate.

FAQFAQCommon edge cases and quick clarifications.+

How do I use the date add/subtract calculator?

Enter the start and end dates, and our calculator will display the date difference in days and months.

Can I change the assumptions in the calculator?

Yes, you can edit the rate and rule fields to match your specific scenario.

Is this calculator original?

Yes, our date add/subtract calculator is an original implementation with rewritten formulas, labels, and copy.

What is the purpose of the notes section?

The notes section provides additional information and cautions to ensure accurate use of the calculator's estimates.

Can I use this calculator for financial or legal decisions?

No, this calculator is for planning purposes only. Please consult official sources or experts for financial or legal decisions.

MAPRelated CalculatorsNeighboring tools in the same decision flow.+