Date Calculator

✓ Free online calculator · No signup · Instant results

Add or subtract days, weeks, months, and years from any date, or calculate the number of days between two dates. Find out your exact age with the Age Calculator, or work with time durations using the Time Calculator. Planning a move? Our Relocation Cost Calculator helps estimate costs and timeline.

Enter a start date and choose how many days, weeks, months, or years to add or subtract—and see the resulting date instantly.

Days Between Two Dates

How the Date Calculator Works

The date calculator handles two common tasks: adding/subtracting time from a date, and finding the difference between two dates.

When adding months or years, the calculator preserves the day of month when possible. It correctly handles month-end dates and leap years.

Date Calculation Examples

Example 1: Employment Contract Notice Period

Sarah has been employed for 5 years and wants to calculate her notice period. Under UK employment law, she is entitled to a minimum 5-week notice period. She uses the calculator: Start date = today (March 18, 2026), add 35 days → Notice expires April 22, 2026. She also checks the business days: 25 working days until her last day.

Example 2: Project Deadline Planning

A development team starts a project on March 18, 2026 with a deadline of June 30, 2026. Using "Days Between Dates": 103 calendar days total, 74 business days. They divide 103 days into 4 sprint phases: ~26 days each. The calculator helps them set interim milestones on April 13, May 9, and June 4.

Example 3: Days Until a Birthday or Holiday

Tom wants to know how many days until his birthday on July 25, 2026. Start date: March 18, 2026, End date: July 25, 2026 → 129 days remaining, 92 business days. He also checks: 18 weeks and 3 days until the celebration, giving him time to plan ahead.

Common Date Calculation Use Cases

FAQ

How many days are between two dates?
Enter your start and end dates in the 'Days Between Dates' mode, then click Calculate. The calculator instantly shows the total number of calendar days between the two dates. For example, from January 1 to March 31 is 89 days (or 90 in a leap year).
Does the calculator include or exclude the start/end date?
By default, the calculator counts the end date but excludes the start date — the same convention used in most financial and legal contexts. For example, January 1 to January 31 = 30 days. If you need to include both endpoints, add 1 to the result.
What are workdays and how are they calculated?
Workdays (business days) are Monday through Friday, excluding weekends. The calculator shows both calendar days and business days in its results, making it easy to track deadlines that follow a 5-day work week. Note: public holidays are not automatically excluded.
How do I calculate 30 / 60 / 90 days from today?
Switch to 'Add/Subtract Days' mode, enter today's date as the start date, and type 30 (or 60, 90) in the days field. Click Calculate to see the resulting date. This is useful for invoice due dates, subscription trials, and legal deadlines.
How do I add months to a date?
Use the 'Add/Subtract Days' mode and convert months to days manually: 1 month ≈ 30 days, 3 months ≈ 90 days, 6 months ≈ 180 days, 12 months ≈ 365 days. For exact month boundaries, count the actual days in the relevant months (e.g., January has 31 days, February has 28 or 29).
How do I find what date is 100 days from now?
In 'Add/Subtract Days' mode, set the start date to today, enter 100 in the days field, and choose 'add'. The result shows exactly which date falls 100 days from now, including the day of the week — helpful for project milestones and delivery estimates.
How are leap years handled in date calculations?
The calculator automatically accounts for leap years. February 29 exists only in leap years (divisible by 4, except century years unless also divisible by 400). So calculating from February 1 to March 1 is 28 days in a normal year but 29 days in a leap year like 2024.
How to calculate a contract deadline or notice period?
Enter the contract start date or signing date, then add the notice period in days. For example, a 3-month notice period from October 1 would be approximately October 1 + 90 days = December 30. Always verify the exact month lengths for contractual accuracy.
How to find the date X weeks from a given date?
Multiply weeks by 7 to get days. 2 weeks = 14 days, 4 weeks = 28 days, 6 weeks = 42 days. Enter this number in 'Add/Subtract Days' mode. For example, 6 weeks from April 1 = April 1 + 42 days = May 13.
What is the difference between calendar days and business days?
Calendar days count every day including weekends and holidays (7 days per week). Business days count only Monday–Friday (5 days per week). A 10-business-day deadline from a Monday equals 14 calendar days. This calculator shows both, so you can use whichever applies to your situation.
How to calculate pregnancy due date from last period?
Add 280 days (40 weeks) to the first day of the last menstrual period. In 'Add/Subtract Days' mode, enter the LMP date and add 280. This gives Naegele's rule estimated due date. Actual due dates vary; always consult a healthcare provider for medical guidance.
How to find days until a future event (birthday, holiday)?
In 'Days Between Dates' mode, set the start date to today and the end date to your event. The result shows how many days remain. For example, if today is March 1 and Christmas is December 25, there are 299 days until Christmas.
How to calculate age between two specific dates?
Enter the birth date as the start date and today (or any other date) as the end date in 'Days Between Dates' mode. Divide the result by 365.25 to get approximate age in years. For example, 10,000 days = approximately 27.4 years.
How do I subtract 6 months from a date?
In 'Add/Subtract Days' mode, choose 'subtract' and enter approximately 180 days (for 6 months). For exact results, count the actual days in the 6 months you're subtracting. From September 1 going back 6 months lands around March 1–4 depending on the months involved.
Can this calculator handle dates across different time zones?
This calculator works with calendar dates only (year/month/day) and does not account for time zones or daylight saving time shifts. For cross-timezone scheduling, use the date result as a reference and apply your local timezone offset separately.

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Age CalculatorCalculate your exact ageTime CalculatorAdd and subtract time