Work Schedule Time Zone Converter
Convert an employee's working hours into the company's time zone and measure how many hours overlap with the required collaboration window. Use it when hiring remote workers or evaluating schedule fit for distributed teams.
About this calculator
Remote teams need to know not just what time an employee starts, but how many of those hours land inside the company's core business window. This calculator shifts the employee's start and end times by the UTC offset difference (companyTimezone − sourceTimezone) and then computes the intersection with the full company day (0–24). The key formula steps are: companyStart = (start + tzDiff + 24) % 24 and companyEnd = (end + tzDiff + 24) % 24. If the shifted window does not cross midnight, overlap = min(companyEnd, 24) − max(companyStart, 0); if it wraps past midnight, the two segments are summed. The final result is capped at the required overlap hours, showing whether the employee's schedule fully satisfies the collaboration requirement or falls short. A result equal to the required overlap means full coverage; anything less reveals a gap.
How to use
An employee in UTC+3 works 09:00–17:00 and the company HQ is at UTC−5. Required overlap is 4 hours. Set workStartTime = 09:00, workEndTime = 17:00, sourceTimezone = 3, companyTimezone = −5, overlapRequired = 4. tzDiff = −5 − 3 = −8. companyStart = (9 − 8 + 24) % 24 = 25 % 24 = 1. companyEnd = (17 − 8 + 24) % 24 = 33 % 24 = 9. The employee's hours appear as 01:00–09:00 HQ time. Overlap with HQ day = min(9, 24) − max(1, 0) = 8 hours. Capped at overlapRequired = 4. Result: 4 hours — the schedule fully satisfies the 4-hour overlap requirement.
Frequently asked questions
How do I check if a remote employee's schedule overlaps enough with headquarters time?
Convert the employee's local start and end times to HQ time by adding the UTC offset difference, then measure the intersection of that shifted window with the HQ workday. This calculator performs all three steps — conversion, intersection, and cap — automatically. If the result equals your required overlap hours, the schedule works. If it is less, the employee would need to shift their hours or your team would need to accept asynchronous workflows for the missing time.
What UTC offset should I enter for time zones that observe daylight saving time?
Always enter the offset that is currently active, not the standard-time offset. For example, US Eastern Standard Time is UTC−5, but during daylight saving it becomes UTC−4. Using the wrong offset introduces a 1-hour error in the conversion, which can misrepresent overlap by a full hour. It is best practice to recalculate at the seasonal transitions in March and November (for North America) and late March and October (for Europe) to ensure your remote team's schedules remain correctly aligned throughout the year.
Why does a work schedule that crosses midnight complicate time zone overlap calculations?
When a shifted schedule wraps past 24:00 — for example, an employee whose HQ-converted hours run from 22:00 to 06:00 — a simple subtraction produces a negative number. The correct approach splits the window into two segments: the hours from the start to midnight, and the hours from midnight to the end, then sums them. This calculator handles that automatically via the modulo-24 logic. Ignoring the midnight-crossing case is a frequent bug in manual spreadsheets that leads to either wildly inflated or negative overlap figures.