Date Calculator
Calculate the difference between two dates, add/subtract time from a date, or find the day of the week.
About Date Calculator
Date Calculator works out how much time sits between two dates, adds or subtracts days, weeks, months, or years from a starting date, and tells you which day of the week any date falls on. Reach for it when you're counting down to a deadline, figuring out a contract end date, or settling a 'how many days until' question. It runs entirely in your browser, so nothing you type is sent anywhere.
- Category
- create
- Input
- No file input — params only.
- Output
- Outputs: application/json.
- Cost
- Free, runs in your browser
- Memory
- low
Common uses
- Count the exact number of days between a project kickoff and its launch date for billing or reporting
- Add 90 days to a contract signing date to find the renewal or notice deadline
- Work out how many weeks of paid leave fall between two dates for a payroll calculation
- Find which day of the week a future event lands on so you can plan around weekends
- Subtract 6 months from today to set a 'last active' cutoff for cleaning up a user list
- Calculate a baby's exact age in days, weeks, and months from a birth date
Frequently asked questions
Does it count the start and end day, or just the gap between them?
It reports the difference between the two dates. Whether the endpoints are inclusive depends on the calculation mode; the JSON output shows the raw day count so you can adjust by one if your context needs inclusive counting.
Can it handle leap years and varying month lengths?
Yes. Adding months or years follows the calendar, so February, 30-day months, and leap days are all accounted for in the result.
Do I need to upload a file?
No. You enter dates directly and the math happens in your browser. There's nothing to upload and nothing leaves your device.
What format is the output?
It returns JSON with the breakdown (days, weeks, months, years, day of week as applicable), which you can copy or feed into another tool.
Does it account for time zones?
The calculator works on calendar dates, not clock times, so time zones don't shift the result. For epoch timestamps and time-of-day conversions, use the Timestamp Converter instead.
Keywords
- date
- calculator
- difference
- days
- weeks
- months
- years
- calendar