Date Calculator
What date is 30 days from today? 90 days from a contract signing? Add or subtract days, weeks, months, or years from any date and get the exact day of the week.
30 days after Jun 11, 2026
Saturday, July 11, 2026
Counts calendar days, including weekends and holidays — deadlines defined in business days run longer (use the business days calculator for those). Month arithmetic clamps to month-end: one month after January 31 is the last day of February.
How Date Arithmetic Works
Adding days is exact — every day counts, weekends included. Months are where it gets interesting: months differ in length, so “one month later” means the same day-of-month where possible, clamped to month-end where not. Deadlines, leases, loan grace periods, and return windows are nearly always calendar days unless the contract says “business days” explicitly.
Quick reference
+30 days ≈ 1 month +90 days ≈ 3 months +45 days ≈ 6½ weeks +180 days ≈ 6 months 30 calendar days ≈ 22 business days 90 calendar days ≈ 64 business days Month-end clamp: Jan 31 + 1 month = Feb 28 (or 29)
Frequently Asked Questions
What date is 90 days from today?
It changes every day, which is why the calculator anchors to today's date automatically — 90 days is roughly three months out, the standard window for probation periods, prescription refills, and 90-day return policies. Use the +90 quick button and you'll get the exact weekday too.
Are deadlines counted in calendar days or business days?
Calendar days unless the contract or statute explicitly says 'business days.' The difference compounds fast: 30 calendar days is about 22 business days, and 90 calendar days is about 64. When a deadline matters legally, check the document's definitions section before counting.
Why does adding a month to January 31 give February 28?
Because February has no 31st, the result clamps to the month's last day — that's the standard convention used by banks, leases, and this calculator. The alternative (rolling into March 2 or 3) is what naive software does, and it's almost never what a contract means by 'one month later.'
Is adding 365 days the same as adding one year?
Only in non-leap years. Adding 'one year' keeps the same month and day (March 15 → March 15), while adding 365 days lands one day earlier whenever a February 29 falls in between. For birthdays and anniversaries use years; for interest periods and contracts, follow the document's wording.