How the calculation works
The calculator works with calendar dates in UTC, so time zones and daylight saving time never move a date.
- Renewal dates: start date + initial term in months gives the first renewal date. Later renewal dates add the renewal term each time, always counted from the original start date (start + initial term + 1 × renewal term, + 2 × renewal term, and so on).
- Term end: the day before the renewal date. A 36-month term starting March 1, 2025 runs to February 29, 2028 and renews on March 1, 2028.
- Month ends: when the target month has no matching day, the date moves to that month’s last day. January 31 + 1 month is February 28, or February 29 in a leap year. Leap years follow the Gregorian rule: every fourth year, except century years not divisible by 400.
- Last day to give notice: the renewal date minus the notice period. A period in days counts calendar days; a period in months uses the same month-end rule. Notice must be given on or before this date.
- Review start dates: 120, 90 and 60 days before the last day to give notice. These are planning lead times, not contract terms: 120 days leaves room to gather usage and invoices, request quotes and negotiate; 60 days is a late start.
- Which term is current: the calculator compares the dates with today’s date (UTC). If this term’s notice deadline has passed, it shows the next deadline as well. A contract with no auto-renewal (renewal term 0) shows the term end only.
The calendar file has up to three all-day events for the next deadline: the earliest review date that hasn’t passed, the last day to give notice, and the renewal date (or the term end for a contract that doesn’t auto-renew). Each event has an alert: the day before for the review and the renewal, a week before for the notice deadline. The file is built in your browser; nothing is stored.
Worked example
A managed network contract started on March 1, 2025 with a 36-month initial term. It auto-renews for 12 months at a time unless either side gives 90 days’ notice. Checked on October 13, 2026:
- The first renewal date is March 1, 2025 + 36 months = March 1, 2028, so the initial term ends on February 29, 2028 (2028 is a leap year).
- The last day to give notice is March 1, 2028 − 90 days = December 2, 2027.
- Start the review by August 4, 2027 (120 days before the notice deadline), September 3, 2027 (90 days) or at the latest October 3, 2027 (60 days).
- If no one gives notice, the next renewal dates are March 1, 2029 (notice by December 1, 2028), March 1, 2030 (notice by December 1, 2029) and March 1, 2031 (notice by December 1, 2030). The second term ends on February 28, 2029, because 2029 is not a leap year.
Before you rely on these dates
Contracts define notice in different ways. Check the actual clause for:
- When notice counts: on receipt, on sending, or a set number of days after mailing.
- Business or calendar days: a period in business days ends earlier on the calendar than the same number of calendar days.
- The anchor date: clauses commonly count back from the end of the term or the renewal date; some use the anniversary of the effective date or the date service was accepted.
- How notice must be given: a named address, certified mail, email to a specific mailbox or a provider portal. Notice sent the wrong way may not count.
- The renewal term: some contracts renew for the original term, some for one year, some month to month. An order form can override the master agreement.
The dates here are a planning aid, not legal advice. When the deadline matters, give notice early and keep proof that it was sent and received. Our contract renewal page covers what to do with the time before a renewal.
