Use this free date calculator to find the number of days between two dates, or figure out what date it will be after adding or subtracting days, weeks, months, or years. It is fast, simple, and works entirely in your browser.
Find the full difference between two calendar dates, including total days, weeks, months, and years.
Start from any date, then move forward or backward by days, weeks, months, or years.
This online date calculator combines two common date tasks into one simple tool. The first mode calculates the difference between two dates, making it useful for project planning, deadlines, subscriptions, and age or duration checks. The second mode calculates future or past dates by adding or subtracting days, weeks, months, or years from a starting date.
Because everything runs directly in your browser, the tool feels instant and private. It is ideal for everyday planning, contracts, schedules, events, shipping estimates, and content calendars.
The date difference mode measures the elapsed interval between a start date and an end date. It reports total days and weeks while also presenting a calendar-style breakdown in years, months, and days. These values answer different questions. Total days are useful for billing periods, service windows, travel plans, and countdowns. Calendar years and months are easier to read when checking an age, employment period, lease term, or long-running project.
Elapsed time normally excludes the starting day. For example, the time from April 1 to April 2 is one day. If a policy or event requires inclusive counting, add one day to the displayed total. This distinction matters for hotel stays, medication schedules, legal notice periods, and any process whose rules explicitly count both boundary dates.
The date offset mode starts with one calendar date and moves forward or backward by the amount you choose. Days and weeks are useful for delivery estimates, follow-up reminders, trial periods, and short deadlines. Months and years work with calendar boundaries, so results respect different month lengths and leap years. Adding one month to a date near the end of a month can therefore behave differently from adding a fixed number of days.
After calculating an offset, review the formatted date, weekday, ISO value, and timestamp. The readable date is convenient for people, while an ISO date is easier to paste into spreadsheets, databases, issue trackers, and API requests. The weekday helps confirm business schedules and event plans without opening another calendar.
Confirm that both dates use the intended local calendar day before relying on the result. Date-only calculations avoid most time-zone issues, but timestamps from other systems may represent UTC or another region and can appear one day earlier or later after conversion. For contracts, payroll, taxes, or legal deadlines, also check whether weekends and public holidays should be excluded, because this calculator measures calendar time rather than business days.
Keep a copy of the original dates and note whether your method is elapsed or inclusive. That small detail makes the result easier to reproduce and explain later. All calculations happen on your device, so you can test different scenarios without uploading dates or creating an account.