Project Deadline Calculator
Add business days to a start date and generate a realistic project schedule that respects weekends and holidays.
Working week
Project phases
Break work into phases with duration and optional buffer. Milestones can anchor to phase ends.
Milestones
Your project
0
working days remaining
Deadline: September 5, 2026
Start: September 5, 2026
AT RISK
| Phase | WD | Buffer | Start | End | Status |
|---|---|---|---|---|---|
| Discovery | 5 | 1 | 2026-09-05 | 2026-09-14 | not-started |
- Kickoff complete — 2026-09-14 (pending)
What is a project deadline, and what goes on one?
The deadline calculator helps you work backward from a final due date to set milestone dates, factor in buffer days, and account for non-working days like weekends and holidays.
Key components
- Final deadline — the hard due date from your client.
- Milestones — intermediate deliverable dates.
- Buffer days — extra time for revisions or unexpected delays.
- Working days only — automatically skips weekends.
How to use this tool
- Enter the project start date.
- Input the estimated working hours required.
- Specify your daily available hours for this specific project.
- The tool will calculate the earliest realistic completion date.
Why this matters
Promising arbitrary deadlines leads to crunch time and poor work quality. Calculating deadlines based on actual capacity sets realistic client expectations.
Works well with
Capacity Planner
Model weekly capacity against project commitments, see an eight-week forecast, and sanity-check new work before you say yes
Weekly Planner
Plan your week in a time grid with goals, recurring blocks, drag-and-resize scheduling, and reflections — saved locally in your browser
Estimate Maker
Send professional project estimates and quotes to clients
Frequently asked questions
Instead of asking when you will finish, you start from a fixed deadline and calculate the latest date you can start while still fitting the required working days.
Extra working days after a phase to absorb delays. Many teams add roughly 10–20% buffer to critical phases.
Yes. Enter dates as YYYY-MM-DD, one per line, in the holidays field. Those days are excluded from working-day counts.
Calendar days include weekends and holidays. Working days only count days you marked as workdays and that are not holidays.
Use Add to calendar (.ics) to download a file you can import into Google Calendar, Outlook, Apple Calendar, or any app that supports iCalendar.
Choose Backward: from deadline, enter the deadline date and how many working days you need. The tool shows the start-by date.
Phases as horizontal bars (with hatched buffer), milestones as diamonds, a red dashed line for today, and an orange line for the project deadline.
In the Timeline tab on a wide screen, click a milestone diamond to toggle pending vs complete. Click a phase bar to change phase status.