30
days
22
days
4.3
weeks
8
days
30
days
22
days
4.3
weeks
8
days
The Deadline Calculator computes the exact deadline date by adding a specified duration to a start date. Whether you are calculating a project deadline 90 days from kickoff, a contract expiry 6 months from signing, a legal filing due 30 days after service, or a warranty end date 1 year from purchase, this calculator handles all common duration types and shows you both the calendar deadline and the number of business days in the period.
Deadline calculations seem simple until they are not. Adding '30 days' to January 31 gives March 2 in non-leap years (not February 30, which does not exist). Adding '6 months' to August 31 gives February 28 or 29 — the month has fewer days. Legal and contractual deadlines must follow specific rules about how these edge cases are handled, and an error can have serious consequences: missed statutes of limitations, contract breaches, or regulatory penalties.
The distinction between calendar days and business days is crucial. A 30-calendar-day deadline starting March 1 ends March 31. But if only business days count, 30 business days starting March 1 extends well into April — approximately April 11 in a typical month with 10 weekend days. Courts, tax authorities, and contract law often specify which type of day count applies, and this calculator shows both figures simultaneously.
Common use cases include: project management (sprint deadlines, milestone dates, phase timelines), legal and compliance (statute of limitations, response deadlines, regulatory filing due dates), human resources (probationary periods, notice periods, benefits waiting periods), finance (loan terms, invoice payment due dates, subscription renewals), and education (assignment due dates, registration deadlines, semester end dates).
For legal deadlines specifically, always consult with a qualified attorney to verify the correct calculation method for your jurisdiction. Many courts have specific rules about whether the first day counts, how to handle deadlines falling on weekends or holidays, and what 'months' means in different contexts.
For day and week durations: end_date = start_date + (duration x days_per_unit). For month durations: adds 30 days per month as an approximation — for exact calendar month arithmetic, use the Add/Subtract Days from Date calculator. Business days are counted by iterating through each day in the period and counting non-weekend days (Monday-Friday). Holiday exclusion is not included in the base calculation.
The 'Business Days in Period' count is the number of Monday-Friday days between start and deadline. For deadlines measured in business days, this is the operative figure. If the deadline date falls on a weekend, most legal and business conventions advance it to the next Monday — adjust accordingly.
Inputs
Results
30 calendar days from March 15 = April 14; there are 22 business days within that period
Inputs
Results
6 months (180 days) from January 1 = July 1; 130 business days available in the period
Enter today as the start date, 30 as the duration, and 'Days' as the unit. The result shows the exact date 30 calendar days from your start date, plus the number of business days in that window.
Calendar days count every day including weekends and holidays. Business days (or working days) count only Monday through Friday, excluding weekends. Some calculations exclude public holidays too — this calculator excludes weekends but not specific holidays.
This calculator approximates months as 30 days. For exact month addition (e.g., January 31 + 1 month = February 28 or 29), use a calendar-specific tool or consult the date arithmetic rules in your jurisdiction.
In most legal and business contexts, a deadline falling on a Saturday or Sunday is automatically extended to the following Monday. Some regulations specify Friday instead. Always verify the applicable rule for your specific context.
It depends on the context. For simple calendar-day deadlines, holidays are included. For business-day deadlines, many calculations also exclude public holidays — this calculator excludes weekends but not holidays, so manually add holiday days if needed.
Federal courts use Federal Rule of Civil Procedure Rule 6, which generally excludes the day of the triggering event, counts all calendar days (unless the deadline is less than 11 days), and extends to the next non-holiday business day if the deadline falls on a weekend or holiday.
A statute of limitations is the legal deadline by which a lawsuit must be filed. For example, personal injury claims in many US states must be filed within 2-3 years of the injury. Missing this deadline typically bars the claim entirely, regardless of its merits.
Use the contract execution date as your start date, and the contractual term (e.g., '90 days,' '1 year,' '6 months') as the duration. Check whether the contract specifies calendar days or business days, and whether the start day itself counts.
'Net 30' means payment is due within 30 calendar days from the invoice date. Similarly, 'net 60' = 60 days, 'net 90' = 90 days. If your invoice is dated March 1, a net-30 payment is due by March 31.
90 business days equals 18 calendar weeks exactly (90 / 5 days per week = 18 weeks). In calendar days, 90 business days spans approximately 126 calendar days (18 weeks x 7 days), not accounting for holidays.
Roboculator Team
The Roboculator Team explains calculations, planning tools, and practical formulas in clear language for real-life situations.
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