Date Calculator
Calculate duration between dates or add/subtract days
Date Calculator
dateCalculator.component.description
📊 Timeline Visualization
📈 Additional Information
Date Calculator Guide
Calculate the difference between two dates, or add/subtract time from a specific date. Perfect for planning events, calculating age, tracking milestones, or determining project timelines.
Three Calculation Modes
Date Difference
Calculate the exact time span between two dates with precision down to years, months, and days. Results show the difference in multiple formats: total days, weeks, months, hours, and a detailed breakdown.
Add to Date
Add a specific duration (years, months, days) to a starting date to find a future date. Useful for:
- Project deadline calculations
- Contract expiration dates
- Subscription renewal dates
- Baby due date estimates
Subtract from Date
Subtract a duration from a starting date to find a past date. Helpful for:
- Backdating contracts or agreements
- Calculating conception dates
- Determining when to start projects
Understanding Business Days
The calculator shows both total days and workdays (Monday-Friday). This distinction is crucial for:
- Project Planning: Accurate timeline estimates excluding weekends
- Delivery Estimates: "5-7 business days" calculations
- Legal Deadlines: Many legal terms count business days only
- Payroll: Work period calculations
Common Use Cases
- Age Calculation: Find exact age in years, months, and days
- Anniversary Tracking: Calculate time since important dates
- Countdown Timers: Days until vacations, events, or deadlines
- Retroactive Dating: Calculate past dates for documentation
- Lease Agreements: Calculate end dates from start dates and terms
- Payment Terms: Net 30, Net 60, etc. calculations
Date Calculation Accuracy
The calculator accounts for:
- Varying month lengths (28-31 days)
- Leap years (February 29th)
- Calendar transitions
- Weekend identification (Saturday-Sunday)
💡 Date Tips
Frequently Asked Questions
How does the calculator handle leap years?
The calculator automatically accounts for leap years when calculating date differences and date arithmetic. February 29th is included in leap years (divisible by 4, except century years must be divisible by 400). This ensures accurate day counts across all date ranges.
What's the difference between total days and business days?
Total days includes every calendar day (all 7 days of the week). Business days (workdays) only count Monday through Friday, excluding weekends. For example, a 10-day period might only have 6-8 business days depending on how it aligns with weekends.
Can I calculate someone's exact age with this tool?
Yes! Use the "Date Difference" mode. Enter the person's birthdate as the start date and today's date (or any reference date) as the end date. The calculator will show their exact age in years, months, and days, plus total days lived.
How do I calculate a deadline that's "90 days from today"?
Use the "Add to Date" mode. Set today's date as the base date, then enter "0" for years, "0" for months, and "90" for days. The calculator will show the exact calendar date 90 days from now, including what day of the week it falls on.
Does this calculator account for different time zones?
The calculator works with calendar dates only and doesn't account for time zones or specific times of day. It calculates full calendar days between dates. For precise timestamp calculations across time zones, you'd need a time zone converter.
How do I calculate a "Net 30" payment due date?
Use "Add to Date" mode. Enter the invoice date as the base date, then add "0" years, "0" months, and "30" days. The result shows when payment is due. For "Net 60" or "Net 90," change the days accordingly. The calculator will also show the day of the week, helping you avoid weekend payment dates. Note that some industries count business days only—check with your specific contract terms.
Why does adding "1 month" sometimes add different numbers of days?
Months have varying lengths (28-31 days), so adding "1 month" means moving to the same day number in the next month, not adding exactly 30 days. For example: January 15 + 1 month = February 15 (31 days later), but February 15 + 1 month = March 15 (28-29 days later). This ensures dates align correctly across months rather than creating drift over time.
What happens if I add time that results in February 30th?
The calculator intelligently handles invalid dates. If an operation would create February 30th or 31st, it adjusts to the last valid day of February (28th or 29th in leap years). For example, January 31 + 1 month = February 28/29, not an error. Similarly, if you're on the 31st and add months to a 30-day month, it adjusts to the 30th.
How can I calculate how long until my next birthday?
Use "Date Difference" mode. Enter today's date as the start and your next birthday as the end date. The calculator shows exactly how many months and days until your birthday. For recurring annual events, note the day of the week to plan celebrations. You can also use "Subtract" mode to see when to start party planning (e.g., subtract 30 days from your birthday to get planning start date).
Can I use this for pregnancy due date calculations?
Yes! From the first day of the last menstrual period (LMP), add 280 days (or 9 months, 7 days) using "Add to Date" mode. However, for medical accuracy, always consult with your healthcare provider, as they may adjust based on ultrasound measurements. The calculator gives you a general estimate and shows which day of the week the due date falls on.
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