# Date Calculator

> Calculate duration between dates or add/subtract days from a starting point.

Page: https://askcalculators.com/calculator/date-calculator/
Definition: https://askcalculators.com/calculator/date-calculator/definition.json
JSON Schema: https://askcalculators.com/calculator/date-calculator/schema.json
Version: 7.0.0
Maintained by: AskCalculators (software project; not a credentialed reviewer)
Qualified review: pending. Automated checks do not establish professional approval.
Page status: Live
Review status: Pending

## Use
Open the calculator page and enter values. Query-string parameters can restore and bookmark a calculation.
Example: https://askcalculators.com/calculator/date-calculator/?daysToAdd=0&mode=diff

## Inputs
- startDate: Start Date; type=date; optional; default=today
- endDate: End Date; type=date; optional; default=
- daysToAdd: Days to Add (±); type=number; optional; default=0
- mode: Mode; type=select; optional; default=diff

## Outputs
- result: Result; format=text; primary

## Formula
The selected number of calendar days, weeks, months, or years is added to or subtracted from the start date using UTC calendar arithmetic.

## Rules
- Empty optional inputs are undefined, not zero.
- Hidden conditional inputs are ignored.
- Do not invent missing required inputs.