Meeting Planner by Time Zone
This Meeting Planner translates a chosen UTC time into local times for up to five participants and evaluates whether the time falls within each participant's declared working hours. It supports two workflows: converting from a UTC time and converting from the organizer's local time.
The tool provides an immediate compatibility indicator (fraction of participants within working hours) and a fairness score that measures how close participants' local times are to their mid-work hours. Use small participant lists for quick assessments; for full automated search across many days/times use a dedicated scheduler UI.
Take a UTC time (minutes since UTC midnight) and list each participant's local time in minutes and hour-of-day; report whether that local time falls inside the participant's defined working window.
Inputs
Results
Participant 1 local time (minutes since local midnight)
240
Participant 1 local hour (decimal)
4
Participant 1 within working hours
0
Participant 2 local time (minutes since local midnight)
600
Participant 2 local hour (decimal)
10
Participant 2 within working hours
1
Participant 3 local time (minutes since local midnight)
1,080
Participant 3 local hour (decimal)
18
Participant 3 within working hours
0
Participant 4 local time (minutes since local midnight)
540
Participant 4 local hour (decimal)
9
Participant 4 within working hours
0
Participant 5 local time (minutes since local midnight)
660
Participant 5 local hour (decimal)
11
Participant 5 within working hours
0
Active participants
3
Total within working hours
1
Fraction within working hours (%)
33.33%
| Output | Value | Unit |
|---|---|---|
| Participant 1 local time (minutes since local midnight) | 240 | minutes |
| Participant 1 local hour (decimal) | 4 | hours |
| Participant 1 within working hours | 0 | — |
| Participant 2 local time (minutes since local midnight) | 600 | minutes |
| Participant 2 local hour (decimal) | 10 | hours |
| Participant 2 within working hours | 1 | — |
| Participant 3 local time (minutes since local midnight) | 1,080 | minutes |
| Participant 3 local hour (decimal) | 18 | hours |
| Participant 3 within working hours | 0 | — |
| Participant 4 local time (minutes since local midnight) | 540 | minutes |
| Participant 4 local hour (decimal) | 9 | hours |
| Participant 4 within working hours | 0 | — |
| Participant 5 local time (minutes since local midnight) | 660 | minutes |
| Participant 5 local hour (decimal) | 11 | hours |
| Participant 5 within working hours | 0 | — |
| Active participants | 3 | — |
| Total within working hours | 1 | — |
| Fraction within working hours (%) | 33.33% | — |
Visualization
Methodology
Local time is calculated as: local_time_minutes = utc_time_minutes + UTC_offset_hours * 60. For host-local inputs, UTC is computed as host_local_minutes - host_offset * 60.
Working-window checks compare local hour-of-day to the participant's work start (inclusive) and work end (exclusive) values. The fraction within working hours equals participants_in_window / active_participants.
Fairness score equals the mean squared deviation (hours^2) of participants' local hour from their mid-work hour. Lower scores indicate local times closer to each participant's preferred midpoint.
Worked examples
Example: UTC time 540 (09:00 UTC) with participant offsets -5, +1, +9 and standard 09:00-17:00 windows will produce local hours 04:00, 10:00, 18:00 respectively; fraction within working hours would be 1/3.
Example: Enter organizer local minutes 600 (10:00) with host offset -5 to compute UTC and then participant local times via the host-local method.
Key takeaways
Use the UTC-based method to evaluate a candidate meeting time quickly across participants.
Use the host-local method when scheduling from an organizer's local clock.
For automated search of many candidate slots or to handle DST and daylight transitions automatically, integrate a time zone database and perform rule-based conversions.
Further resources
External guidance
Expert Q&A
Can I include more than five participants?
This calculator supports up to five participants in a single evaluation. For larger teams or automated scanning across many time candidates, use a batch scheduler or API that iterates over candidate UTC times.
How does the tool handle daylight saving time (DST)?
This calculator requires you to enter the current UTC offset for each participant. Because DST rules change by locale and date, enter the correct UTC offset for the meeting date. For production schedulers, consult the IANA time zone database and perform rule-based conversions.
Are results precise to the second?
The tool operates in minutes and hours. It is intended for scheduling-level precision. For sub-minute synchronization (e.g., systems requiring precise timestamps) follow IEEE Precision Time Protocol (PTP) guidance and NIST time sources.
What does the fairness score mean?
The fairness score is the mean squared deviation (in hours^2) of each active participant's local time from their mid-work hour. Lower scores indicate the proposed UTC time is closer to participants' usual working window centers.
What if active participants is zero?
The calculator avoids division by zero by adding a very small constant when computing fractions. If no participants are active, the fraction and fairness metrics are not meaningful; the UI should prompt to activate at least one participant.
Sources & citations
- NIST — Time and Frequency Division — https://www.nist.gov/pml/time-and-frequency-division
- IANA Time Zone Database — https://www.iana.org/time-zones
- ISO 8601 — Date and time format standard — https://www.iso.org/iso-8601-date-and-time-format.html
- IEEE 1588 — Precision Time Protocol (PTP) — https://standards.ieee.org/standard/1588-2019.html
- OSHA — Recommended practices for shift scheduling and worker fatigue — https://www.osha.gov