About Time Calculator

Time Calculator provides free tools for adding durations, finding the interval between two clock times, totaling a weekly time card and converting decimal hours.

How the tools calculate

Each valid input is converted to whole seconds. Addition, subtraction and weekly totals use those exact seconds; decimal values are rounded only for display. A duration can be longer than a day, while a clock time wraps around midnight and shows the day change.

Check a result

Each tool explains its formula and includes worked examples. Copy the result or, on the time card, export a CSV or print a record. For a result you need to rely on, check the input format and compare it with your original records.

Limits

The tools use clock arithmetic. They do not adjust for daylight saving, time zones or calendar-date intervals, and they do not calculate wages, overtime or payroll obligations.

Your calculations run on your device. An account is not required. Read the privacy policy for optional saved cards and data handling.

If you find a mistake, see how to report a calculation issue.