Add & Subtract Business Hours

How to use this calculator

Choose a starting date and time, add or subtract, and whole hours plus minutes. Set your workweek, closures and daily working periods. Choose scheduled or elapsed hours. Calculate to see the resulting date-time and the working periods used along the way.

When adding from closed time, counting begins at the next opening. Subtracting uses the previous closing. Exactly using a period returns its closing boundary when adding, or opening boundary when subtracting. A zero duration returns the original date-time. Overlapping working periods merge. Results must fit within 366 calendar days of the starting date.

A worked example

Friday November 6, 2026 at 16:00 plus three working hours finishes Monday November 9 at 11:00 on a Monday–Friday 09:00–12:00 and 13:00–17:00 calendar. Excluding Monday moves that result to Tuesday.

Can I subtract business hours to find when work must start?

Yes. Choose Subtract business hours to work back through the same calendar. For a sequence of tasks with day-based estimates and a buffer, use Backward Scheduling. These are planning calculations using your rules; no service contract, delivery promise or legal deadline is assumed.

Further reading: Atlassian working-calendar concepts. Your entered rules determine this result.

Which calendar and years are supported?

Use dates from 1900 through 2100 and a result within 366 days. Working periods are same-day intervals; 24:00 is allowed only for their ends. Elapsed mode applies the browser's time-zone data and an explicit repeated-time choice. Scheduled mode counts displayed working minutes without DST changes.

What happens to my dates?

Calculations run on your device. Saving a calculation is optional and keeps it in this browser. A setup link contains the dates and settings you entered; anyone with the link can read them. Use one tab per saved calculator. Clear saved data from Privacy & settings.