Every-N-Days Schedule Generator

Worked example

An every-30-days rule starting January 1, 2027, generates January 1, then January 31, exactly 30 days later, then March 2, another 30 days after that. Notice the schedule drifting steadily later relative to the calendar month itself, since 30 days is a fixed interval that has no fixed relationship to how many days any particular month actually contains. Shorten the interval to 7 days instead, starting from the same January 1, and the schedule becomes a simple weekly cadence, January 1, January 8, January 15, and onward, with no drift relative to the day of the week at all, since 7 divides evenly into the length of a week by definition. The interval you choose is always a fixed day count, never a calendar concept like a month, which is exactly why this generator and a true monthly rule can diverge over time even when they start on the same date.

Common mistakes

• Assuming "every 30 days" behaves the same as "monthly." The two only coincide for the specific months that happen to have exactly 30 days between two given occurrences, not as a general rule.
• Setting the interval to zero or a negative number, which is rejected outright since a schedule needs a real positive gap between occurrences.

Limitations

The generated preview is bounded to 500 occurrences or 5 years, whichever limit is reached first, which keeps the schedule fast to generate and easy to review in full.