Date Calculator
Date difference, duration shift, Unix timestamps, and date info — all instant, all local.
Date Difference
ahead
0 days
0 weeks 0 days
Date Info
Day of week
Tuesday
ISO week
Week 26
Day of year
174 / 365
Quarter
Q2
Days in month
30 days
Leap year
No
From today
Today
Add / Subtract Duration
+ 30 days
Thursday, July 23, 2026
− 30 days
Sunday, May 24, 2026
Unix Timestamp
ISO 8601 2026-06-23T06:38:04.000Z
UTC Tue, 23 Jun 2026 06:38:04 GMT
Local 6/23/2026, 6:38:04 AM
1782172800
About
The Date Calculator covers three common date operations: calculating the exact difference (in days, weeks, months, and years) between two dates; adding or subtracting a duration from a date; and converting Unix timestamps to human-readable dates and back. All calculations run locally in your browser.
How to use
- 1 Select the Date Difference tab to find how many days are between two dates.
- 2 Use Add / Subtract to find a target date by adding a number of days, weeks, months, or years.
- 3 Use the Unix Timestamp tab to convert between epoch seconds and calendar dates.
- Does the date difference calculation include or exclude the start and end dates?
- The difference is calculated as the number of calendar days between the two dates, excluding the start date and including the end date — which is the standard convention for "days between." For example, the difference between 1 Jan and 3 Jan is 2 days.
- What is a Unix timestamp?
- A Unix timestamp (also called epoch time) is the number of seconds that have elapsed since 00:00:00 UTC on 1 January 1970. It is the standard way computers store and transmit dates internally, and is commonly seen in API responses, log files, and database records.
- Can I add business days rather than calendar days?
- The current Add/Subtract tab works with calendar days. To calculate business day offsets (excluding weekends), use the Date Difference result and manually subtract the number of weekend days, or use the built-in business-day mode if available.