Deadline Calculator
Add or subtract days, weeks, months, or years from a start date to find the resulting deadline.
Adding 30 days to January 1, 2026 gives January 31, 2026 — a Saturday.
Results update as you type. Months and years clamp to month-end (so Jan 31 + 1 month = Feb 28, not Mar 3) — the dominant date-library convention.
Formula
Days and weeks are simple millisecond arithmetic. Months and years use month-end clamping: adding 1 month to Jan 31 gives Feb 28 (or Feb 29 in a leap year), not March 3 — matching the dominant date-library convention. Negative amounts go backwards in time.
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Frequently asked questions
Calendar days or business days?▾
Calendar days. For business days only (excluding weekends), use the Working Days Calculator. EU contracts and legal documents often specify which apply — Frist (DE), délai (FR), termine (IT) usually default to calendar days unless 'jours ouvrables' (FR) / 'Werktage' (DE) / 'giorni lavorativi' (IT) is specified for working days.
How are month-end edge cases handled?▾
Clamping: Jan 31 + 1 month = Feb 28 (or Feb 29 in leap years). The calculator picks the last valid day of the target month rather than rolling forward. Same convention as Excel, Google Sheets, dayjs, date-fns, and most major libraries.
Can I use a negative amount?▾
Yes — for going backwards. 'Start − 30 days' = the date 30 days before. Useful for working backwards from a known deadline.
Does this account for EU public holidays?▾
No — public holidays vary widely between member states (and within them by region). If a deadline is contractually adjusted to the next business day when it falls on a holiday, apply that adjustment manually. EU consumer-law deadlines (e.g. 14-day right of withdrawal under the Consumer Rights Directive) are typically calendar-day deadlines, but check the specific instrument.
What about EU public-procurement deadlines?▾
Procurement deadlines under the EU Procurement Directives and individual national rules often have specific weekend/holiday-shift rules. Use this calculator for the initial calendar-day calculation; consult procurement guidance for the rule-of-law shift behaviour.
Can I add a custom unit like weekdays?▾
Not in this calculator — for weekday-only counts, use the Working Days Calculator. The four units (days/weeks/months/years) cover the most common deadline arithmetic.