May 26, 2026 to Jun 10, 2026
- Weeks and days
- 2 weeks, 1 days
- Calendar difference
- 0y 0m 15d
- Direction
- forward
Date Calculator
Add or subtract days, weeks, months, and years from a calendar date, or count full days between two dates. Try 90-day and month-end examples.
Inputs explainedResult checksExample valuesRuns in your browser
Formula steps
- Convert both dates to UTC calendar dates.
- Subtract the timestamps to count full days between dates.
- Also compare calendar year, month, and day parts for a human-readable difference.
Examples
Recent answers
Recent date calculations will appear here.
Date math uses UTC calendar dates to avoid daylight-saving time shifts.
Inputs and recent answers stay in this browser tab and are not sent to a server.
How to use the Date Calculator
- Choose Difference when you need days between two calendar dates.
- Choose Add or subtract when you want a date before or after a starting date.
- Enter dates in YYYY-MM-DD form so month and day order stay clear.
- Check the start-date, business-day, holiday, and time-zone rules before using the result as a deadline.
What people use it for
Count full days between deadlines, trips, projects, or events.
Find dates 30, 60, or 90 days before or after a starting date.
Add or subtract offsets such as 45 days, 6 weeks, or 3 months.
Check how many weeks and leftover days sit between two dates.
Avoid daylight-saving surprises by using date-only calendar math.
Quick examples
Two-week deadline
2026-05-26 to 2026-06-1015 days, or 2 weeks and 1 day
Add 90 days
2026-06-16 + 90 days2026-09-14
Subtract 90 days
2026-12-31 - 90 days2026-10-02
Add 45 days
2026-05-26 + 0y 0m 6w 3d2026-07-10
Month-end clamp
2026-01-31 + 0y 1m 0w 0d2026-02-28
Need the guide or a nearby tool?
Need a slower walkthrough, a related calculator, or the full library? These links keep you close to the task you started.
- How to use the Date CalculatorSee slower examples, input meanings, formula notes, result limits, and mistakes to avoid.
- Date & TimeBrowse related calculators and utilities in the same category.
- Calculator and utility guidesFind more guides that use real tool inputs and example numbers.
- All free toolsSearch every live tool, converter, calculator, AI helper, and browser utility.
Frequently asked questions
Plain-language answers about when to use the tool, what it does with your inputs, what to double-check, and how privacy works.
When should I use the Date Calculator?
Use it when your task matches one of these common needs: Count full days between deadlines, trips, projects, or events. Find dates 30, 60, or 90 days before or after a starting date. It works best when you already know the measurements, amounts, units, or options the page asks for.
What is the Date Calculator doing with my inputs?
In plain language: Date difference counts full UTC calendar days between two YYYY-MM-DD dates. Add/subtract mode applies years and months first, clamps month-end dates when needed, then applies weeks and days. The examples on the page are there so you can compare your inputs with a worked example before copying the answer.
What do the main Date Calculator inputs mean?
Start date: the first calendar date in YYYY-MM-DD format. End date: the second calendar date for difference mode. Direction: add moves the date forward; subtract moves it backward. Years, months, weeks, days: the whole-number offset used in add or subtract mode.
How should I read the Date Calculator answer?
Read the headline answer, then check the supporting lines and examples to understand how the calculator got there. If one input changes, rerun the tool and compare the new answer instead of guessing.
What should I double-check before trusting the answer?
Calendar-date math is not the same as time-zone scheduling. Confirm local deadlines, business days, holidays, and time zones separately. Also check the unit, scale, mode, and result limit because small input changes can change the answer.
Does the Date Calculator include the start date?
No. Difference mode counts full days between the two dates. May 26, 2026 to June 10, 2026 is 15 days because May 26 is the starting point, not a completed day.
What happens when I add one month to a month-end date?
The calculator clamps to the last valid day when the target month is shorter. January 31, 2026 plus 1 month becomes February 28, 2026, then any week or day offset is added after that.
Can this count business days or holidays?
No. This page counts calendar days. If weekends, school breaks, bank holidays, or local public holidays matter, check those rules separately before using the result as a deadline.
How do I calculate 90 days from a date?
Choose Add or subtract mode, select Add, enter the starting date, and put 90 in the Days field. For example, 90 calendar days after June 16, 2026 is September 14, 2026. The starting date is day zero for this shift.
How do I find 90 days before a date?
Choose Add or subtract mode, select Subtract, enter the ending date, and put 90 in the Days field. For example, 90 calendar days before December 31, 2026 is October 2, 2026. Check the official rule separately if a deadline counts dates inclusively or excludes weekends and holidays.
Does the site save what I enter?
No. The calculator runs in your browser tab. Your recent answers stay only on the page while you use it, and they are not sent to a server.