About the Date Calculator
The Date Calculator is a free, browser-based tool built for anyone who regularly works with dates. Whether you need to know how many days remain until a contract deadline, calculate the end date of a warranty period, determine how many working days fall within a billing cycle, or simply find out which day of the week a past event fell on — this tool handles it instantly without sending any data to a server.
Common use cases span a wide range of fields. HR and payroll teams use it to measure time between hire dates, calculate notice periods, and count business days in a pay period. Project managers use it to track sprint durations, estimate delivery windows, and count remaining working days before a milestone. Legal and finance professionals use it to compute contract durations to the day, measure SLA windows, and verify whether a deadline lands on a weekend or public holiday. For personal planning, it handles countdowns to weddings, retirements, and product launches, or tracks elapsed time since an anniversary or subscription start.
All five calculators run entirely in your browser with no account required and no data stored anywhere.
How to Use the Date Calculator
This free date calculator gives you five tools in one: date difference, add/subtract intervals, day information, working-day count, and countdown. All calculations run instantly in your browser — no data is sent to a server.
Using Date Difference
Pick two dates and instantly see the gap in days, weeks, months, and years. The broken-down format (e.g., "1 year, 2 months, 3 days") is useful for age calculations, contract durations, and project timelines. If the end date is before the start date the result shows how long ago the start date was.
Using Add / Subtract
Start from any date and add or subtract a number of days, weeks, months, or years. Common uses: finding a deadline 90 days from today, calculating an expiry date, or checking what date falls exactly 6 months from now. Month arithmetic automatically clamps to the last day of the month (e.g., January 31 + 1 month = February 28/29).
Using Day Info
Enter any date to see: day of the week, ISO week number, day of the year, quarter (Q1–Q4), days in that month, and whether the year is a leap year. Useful for scheduling, payroll, academic calendars, and fiscal quarter planning. You can also look up any historical date to find out which day of the week a past event fell on, or confirm whether a future date lands on a weekend.
Using Working Days
Calculate the number of business days between two dates, excluding weekends automatically. Add custom holidays (public holidays, company-specific days off) to exclude them too. The result shows total calendar days, weekend days, holiday days, and net working days — useful for project scheduling, SLA calculations, and HR.
Using Countdown
Set a target date and see exactly how many days, weeks, months, and years remain. Perfect for countdowns to events: weddings, retirements, product launches, or the end of a lease. The display updates every minute so you can leave it open as a live counter. You can also set a past date to measure elapsed time — useful for anniversaries, subscription durations, or how long a project has been running.
Frequently Asked Questions
How many days are between two dates?
Use the Diff tab: pick your start and end dates. The calculator counts every calendar day between them and displays the total in days, weeks, and months.
How do I add 90 days to a date?
Use the Add tab: set your starting date, choose "Add", enter 90, and select "Days". The result shows the exact date 90 calendar days later.
What is a business day calculator?
The Working Days tab counts only weekdays (Monday–Friday) between two dates. You can add custom holidays so they are excluded from the working-day count, giving you the true number of business days for contracts, SLAs, or project planning.
Is this calculator accurate for leap years?
Yes. The calculator handles leap years correctly, including the century rule (years divisible by 100 are not leap years unless also divisible by 400). February 29 is counted when it exists in the date range.