1. What is 90 Days Back Calculator?

This calculator helps you determine the date exactly 90 days prior to a given date, including time calculations. It's useful for various purposes like financial planning, project deadlines, or medical follow-ups.

2. How Does the Calculator Work?

The calculator uses simple date arithmetic:

Where:

• Today — Current date or any specified date
• 90 days — Fixed period to subtract

Explanation: The calculation accounts for varying month lengths and leap years to provide an accurate date exactly 90 days prior.

3. Importance of Date Calculation

Details: Accurate date calculations are crucial for financial transactions, legal deadlines, medical prescriptions, and project planning where specific time periods must be tracked.

4. Using the Calculator

Tips: Enter today's date (or any reference date) in YYYY-MM-DD format. The calculator will automatically compute the date 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 use this for business days only?
A: No, this calculates calendar days. For business days, you would need to exclude weekends and holidays.

Q3: What's the maximum range this can calculate?
A: The calculator can handle any valid date within the range supported by PHP's date functions.

Q4: Can I calculate dates in the future?
A: While designed for calculating past dates, you could modify the formula to add days instead of subtract.

Q5: How precise is the time calculation?
A: The calculation maintains time precision down to the second when time components are included.