# Time Arithmetic

> Quickly add or subtract time values using a 24-hour clock format.

Page: https://askcalculators.com/calculator/time-calculator/
Definition: https://askcalculators.com/calculator/time-calculator/definition.json
JSON Schema: https://askcalculators.com/calculator/time-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/time-calculator/?time1=12%3A00&time2=01%3A30&operation=%2B

## Inputs
- time1: Initial Time (HH:MM); type=time; optional; default=12:00
- time2: Interval to Change; type=time; optional; default=01:30
- operation: Operation; type=select; optional; default=+

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

## Formula
Times are converted to seconds, added or subtracted, then normalized back to hours, minutes, and seconds.

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