1. What Is This Calculator?

This calculator helps you determine the date that was exactly 90 days before a given date. This is useful for various time-based calculations in business, law, and personal planning.

2. How Does It Work?

The calculator uses simple date arithmetic:

The calculation accounts for varying month lengths and leap years automatically.

3. Practical Applications

Details: Useful for calculating deadlines, expiration dates, or tracking time-sensitive processes that require a 90-day lookback period.

4. Using The Calculator

Tips: Enter any valid date in the format YYYY-MM-DD or use the date picker. The calculator will show the date exactly 90 days prior.

5. Frequently Asked Questions (FAQ)

Q1: Does this account for leap years?
A: Yes, the calculation automatically adjusts for leap years and varying month lengths.

Q2: Can I calculate business days instead of calendar days?
A: This calculator uses calendar days. For business days (excluding weekends/holidays), a different calculation would be needed.

Q3: What's the maximum date range I can calculate?
A: The calculator can handle any valid date within the range supported by PHP (typically 1970-2038).

Q4: Can I calculate dates in the future?
A: Yes, by entering a future date, you can see what date would be 90 days before that future date.

Q5: Is the calculation timezone-sensitive?
A: The calculation uses the date only, without considering time or timezone.