Due DateCalculator
Turn "due in 30 days" into a real date. This free Due Date Calculator adds days, weeks or months to any start date — counting calendar days or only business days — and returns the exact deadline dates for projects, tasks and deliverables.
Calculate Your Due Date
Pick a start date and a duration to get the exact deadline.
How the Due Date Calculator Works
Four quick steps to a project deadline.
Set Start Date
Choose the project start date — the day the clock starts running.
Enter Duration
Type a number and choose the unit: calendar days, business days, weeks or months.
Calculate
Press "Calculate Due Date". In business-day mode, weekends are skipped automatically.
View Due Date
See the due date, its weekday and whether it falls on a weekend.
What Is a Due Date Calculator?
The basics of deadline calculation for projects.
Due date calculation
A Due Date Calculator works out the exact day a task, project or deliverable is due. You supply a starting point and the time allowed; it returns the precise deadline.
Whether you count calendar days or business days changes the answer a lot. A "10 business day" deadline normally stretches across 14 calendar days, because two weekends are skipped.
Business days counting
Business days are Monday to Friday. In this mode the calculator steps forward one day at a time and ignores Saturdays and Sundays — the convention for corporate deadlines, bank processing and many legal time limits.
Month-based deadlines
Adding months follows the calendar: one month after March 15 is April 15, while one month after January 31 is February 28 (or 29), since February is shorter. Every month length is handled.
When to Use a Due Date Calculator
Typical deadline planning situations.
Project Management
Fix milestone dates and sprint deadlines from each phase's estimated length.
Assignment Deadlines
Students can turn "due in 10 days" into the real date for homework and papers.
Legal Filing
Estimate court filing deadlines and response dates, many of which are set in business days.
Construction
Forecast completion dates for construction phases, deliveries and subcontractor work.
Creative Projects
Plan content creation deadlines for articles, videos and design work on an editorial calendar.
Business Contracts
Find contract delivery dates and payment due dates so agreed timelines are met.
Due Date Examples
Three common deadline calculations.
30-day project
Start June 1 → due July 1: 30 calendar days, roughly 21–22 of them business days.
2-week sprint
Start on a Monday → 10 business days later is the Monday two weeks on, 14 calendar days in all.
90-day milestone
Start Jan 1 → due April 1 in a non-leap year — a standard quarterly milestone.
Deadline Breakdown
A detailed look at your calculated deadline.
👆 Run the calculator above and the full deadline breakdown appears here.
How Your Project Deadline Is Calculated
The four deadline calculation methods, explained.
Calendar-Day Calculation
Calendar-day mode counts every day after the start date, weekends and holidays included. 30 calendar days after June 1 is July 1, whatever weekdays fall in between.
Business-Day Calculation
Business-day mode moves forward one day at a time but only counts Monday to Friday. Adding 10 business days therefore usually covers 14 calendar days, as two weekends are passed over.
Week-Based Calculation
Week mode multiplies the weeks by 7 and adds that many calendar days, so 2 weeks is simply 14 days with weekends included.
Month-Based Calculation
Month mode moves to the same day number in a later month: 1 month after January 15 is February 15. When that day doesn't exist — January 31 plus one month — the date falls back to the last day of the month, February 28 or 29.
Project Deadline Timeline
Build an interactive project milestone timeline.
Project Start
The timeline begins on the start date chosen in the calculator, and each milestone starts where the previous one finished, building a full schedule.
Milestone Dates
Add a milestone for each phase with a name, a duration and a counting method (calendar or business days). The timeline redraws whenever you add or remove one.
Final Deadline
The final deadline is the end of your last milestone — a quick way to see how calendar days and business days change the overall project length.
Project Deadline Scenarios
Common deadline durations, counted from today.
Tap a scenario card to load it into the calculator above and see its full breakdown. Every date is worked out live from today.
Business Days and Working Days
How calendar days and business days differ.
What Counts as a Business Day?
A business day, or working day, is any weekday from Monday to Friday — the days most offices, banks, courts and government departments are open. When a deadline is set in business days, only those five weekdays are counted.
Are Weekends Included?
Not when you count business days: Saturdays and Sundays are passed over automatically. Five business days from a Monday lands on the following Monday. Calendar-day counting, by contrast, includes every day.
What Happens When a Deadline Falls on a Weekend?
In calendar-day mode a deadline can land on a Saturday or Sunday, and a weekend warning appears so you can decide what to do. In business-day mode the result is always a weekday, because weekends are skipped while counting.
How Holidays Affect a Deadline
Public holidays are not removed automatically, since they vary by country, state and organisation. Add an extra day for each holiday inside your period, and check important deadlines against your local holiday calendar.
Deadline Calculation Examples
Real-world deadline calculations.
Project Deadline Example
A 30-day project starting today, with every day counted — typical for sprints and marketing campaigns.
Assignment Deadline Example
A one-week assignment: exactly 7 days from the start date, weekend included.
Business-Day Deadline Example
Two working weeks: Saturdays and Sundays are skipped, so 10 business days usually covers 14 calendar days.
Milestone Deadline Example
A quarterly milestone: three months later on the same day number, pulled back for shorter months when needed.
Contract Delivery Deadline Example
A 60-day delivery window with every day counted — roughly 43 business days.
What Happens When a Deadline Falls on a Weekend?
How weekend deadlines are treated.
Saturday Deadline
If the due date lands on a Saturday, it is shown exactly as calculated with a weekend warning — it is not moved to Monday for you. Switch to business days when you need a weekday answer.
Sunday Deadline
A Sunday deadline is handled the same way: the date is shown with a weekend warning. Many organisations treat a Sunday deadline as due on Monday, but check the rule that applies to you.
Next Business Day
For a guaranteed weekday deadline, choose business days. Weekends are skipped while counting, so the due date always falls Monday to Friday — what legal filings, banks and corporate deliverables usually require.
Project Deadline Planning
Practical ways to plan project deadlines.
Calculate a Project Completion Date
Start from the project kick-off date and add the estimated duration. For a 90-day software project starting today, you get the exact completion date to share with clients and stakeholders.
Calculate Individual Milestones
Split big projects into phases and chain them in the milestone timeline above: Planning (7 days) → Development (30 days) → Review (14 days) → Delivery, each starting when the last one ends.
Compare Calendar and Working-Day Deadlines
Thirty calendar days is about four weeks; thirty business days is six weeks, or 42 calendar days. Always confirm which one a contract means.
Track Time Remaining
The deadline breakdown counts the days left from today to the due date, so you can tell whether you are ahead, on track or at risk.
Project Kickoff
Requirements & Scope
Build & Implement
Testing & QA
Deadline Met
Deadline Calculation Rules & Limitations
Exactly how this deadline calculator treats each case.
Start Date and Duration
Counting begins on the day after the start date. Start on Monday and add 1 calendar day, and the due date is Tuesday — the start date is day zero.
Calendar Days vs Business Days
Calendar days include weekends; business days count only Monday to Friday. Because a 10-business-day period always contains two full weekends, it takes at least 14 calendar days.
Month-End Dates
Month additions keep the day number when they can. January 31 + 1 month = February 28 (or 29 in a leap year), and March 31 + 1 month = April 30, because those months are shorter.
Weekends
In calendar-day mode a due date may fall on a Saturday or Sunday and is flagged with a warning; in business-day mode weekends are skipped, so the result is always a weekday.
Public Holidays
Public holidays are not subtracted, because they differ by country, state, industry and employer. For deadline-critical work such as legal filings or government contracts, check the result against an official holiday calendar and build in a buffer.
Important Deadline Verification
For high-stakes dates — legal filings, contract obligations, regulatory submissions — treat this tool as a planning aid and confirm the final date through official sources or legal counsel.
Due Date Calculator FAQ
Answers to common questions about the Due Date Calculator.
Pick the start date and add the time allowed — days, weeks or months. You get the precise due date, its weekday, and a warning if it lands on a weekend.
Yes. Choose business days and Saturdays and Sundays are skipped while counting, so 10 business days always ends on a weekday.
Weekends are handled, but public holidays are not, because they differ by country, state and employer. If holidays fall inside your period, add one extra day for each.
Yes. Use the project timeline section to chain phases — say 30 days for phase one, then 45 days starting where phase one ends — or run each milestone through the calculator separately.
The result is flagged as a weekend day. If the deadline must be a weekday, switch to business days or move it to the next Monday yourself.
Yes. It is free with no sign-up, and every date stays in your browser.