| Scenario | Start (local) | Duration | Buffer | Calendar | Outcome |
|---|---|---|---|---|---|
| Site inspection report | 2026-02-17 09:00 | 12 hours | 10% | 09:00–17:00, weekends excluded | Spreads work across two shifts and next day. |
| Commissioning checklist | 2026-02-17 14:30 | 6 hours | 60 minutes | Continuous time | Deadline is same-day evening with buffer. |
| Design review package | 2026-02-17 10:00 | 3 days | 15% | 09:00–17:00, holiday on 2026-02-19 | Holiday pushes deadline to the next working day. |
The calculator converts your duration into minutes and applies a buffer. The total planned effort is: TotalMinutes = BaseMinutes + BufferMinutes.
- Percent buffer: BufferMinutes = BaseMinutes × (Buffer% ÷ 100)
- Fixed buffer: BufferMinutes is converted from your chosen unit
- Continuous time: Deadline = Start + TotalMinutes
- Working hours: minutes are added only within the working window, skipping excluded weekends and listed holidays
- Select your timezone to match the execution location.
- Pick a start time or use the current time.
- Enter the duration and choose minutes, hours, days, or weeks.
- Choose a buffer to reflect uncertainty and review cycles.
- Enable working hours for realistic site or office schedules.
- Set weekend rules and add any holiday dates.
- Press Calculate Deadline to see milestones and countdown.
- Use Download CSV or Download PDF to share results.
Working-Calendar Deadline Mechanics
Every calculation begins by converting your entered duration into minutes, then adding a buffer. In working-hours mode, minutes are applied only inside the daily window, such as 09:00–17:00. If the start time falls outside the window, the clock snaps to the next valid working minute. This approach reflects real engineering execution where labor, equipment access, and supervision are time-bounded.
Buffer Strategy and Risk Allowance
Buffer is treated as planned contingency. A percent buffer scales with task size, while a fixed buffer models approvals or logistics that stay constant. In many engineering workflows, 5–15% covers minor rework, while 20–30% is common for early estimates. Percent buffer follows BufferMinutes = BaseMinutes × (p/100), then rounds to the nearest minute for consistent reporting. The calculator reports base minutes, buffer minutes, and total minutes separately so reviewers can audit assumptions.
Timezone Integrity for Distributed Sites
Projects often span design offices, fabrication yards, and on-site teams. Selecting the correct timezone ensures the displayed deadline matches the operational location. The tool stores timestamps in ISO format and shows a human-readable local time for quick coordination. The live countdown updates each second in the browser, helping supervisors see urgency without refreshing. This reduces confusion when stakeholders compare schedules across regions, especially around midnight boundaries and daylight-saving changes.
Holiday and Weekend Exclusions
Non-working dates can materially shift delivery. When weekends are excluded, Saturdays and Sundays are skipped entirely; when included, they behave like normal days inside the working window. Optional holiday dates further block scheduling, preventing deadlines from landing on known shutdowns. Enter holidays as YYYY-MM-DD; duplicates are ignored for clean exports. For example, a three-day effort with a holiday on day two pushes remaining work into the next open workday.
Milestones, Reporting, and Exports
Milestones at 25%, 50%, 75%, and 100% convert a single deadline into measurable checkpoints. Teams can align inspections, QA holds, and sign-offs to these timestamps. Exports provide a lightweight audit trail: CSV captures inputs and milestone rows, while the PDF report summarizes schedule rules for client communication. Printing uses the same layout for consistent documentation. Over time, saved exports help compare planned versus actual cycles during post-project reviews.
FAQs
1) What is the difference between Working hours and Continuous time?
Working hours adds minutes only inside your daily window and skips excluded non-working days. Continuous time adds minutes straight through 24×7, which suits automated processing or round‑the‑clock commissioning.
2) How should I enter holidays?
Type dates as YYYY-MM-DD, separated by commas or spaces. The calculator treats those dates as non-working and skips them when Working hours is enabled. Duplicate dates are automatically ignored.
3) Can I model night shifts or 24-hour operations?
Yes. Set a night shift window, such as 20:00 to 04:00, only if you use Continuous time. For shift-based scheduling within Working hours, use a single-day window that does not cross midnight.
4) Why does the live countdown change when my device clock is wrong?
The countdown runs in your browser and uses your device time. If your clock is fast or slow, the remaining time will be skewed. Correct your system time, then reload the page for accurate tracking.
5) How are days and weeks interpreted?
When Working hours is enabled, you can treat days and weeks as working time based on your daily window. If you switch to calendar time, days and weeks use standard 24-hour days and 7-day weeks.
6) What data is included in the exports?
CSV includes inputs, computed totals, and milestone rows for spreadsheets. PDF includes a formatted report with the start, deadline, calendar rules, and milestone table. Both help document assumptions during reviews.