Date Calculator

Q: What does the Include End Day option do?

When you turn on Include End Day , the calculator adds one extra day to the total. For example, if you pick January 1 to January 3, the normal count is 2 days. With Include End Day on, it becomes 3 days because January 3 itself is counted.

Q: How do I exclude holidays from my day count?

Click Holiday Settings below the date fields. Select Do not count holidays . Then check the holidays you want to skip. Press Calculate, and those days will be removed from your business day total.

Q: Can I add my own custom holidays?

Yes. Open Holiday Settings and scroll to the Custom Holidays section. Type a name, pick a month, and pick a day. Click Add More if you need extra rows. You can add up to 20 custom holidays.

Q: What does Business Days Only do in the Add/Subtract tab?

When you turn on Business Days Only , the calculator skips weekends and excluded holidays while counting days and weeks. So if you add 10 business days, it jumps forward 10 weekdays instead of 10 calendar days.

Date Calculator

Updated May 27, 2026 By Jehan Wadia

Introduction

This free date calculator helps you find the number of days, weeks, months, and years between two dates. You can also add or subtract time from any date to get a new date. It counts total days, business days, and weekend days. You can even exclude US holidays from your count. Use it to figure out deadlines, plan events, track how many days until a big date, or count workdays for a project. Just pick your dates, hit calculate, and get your answer in seconds.

How to Use Our Date Calculator

This calculator helps you find the number of days between two dates or add and subtract time from any date. Enter your dates and options below to get instant results.

Date Difference Tab

Start Date: Pick the first date you want to count from.

End Date: Pick the second date you want to count to.

Include End Day: Turn this on if you want the end date itself counted as one extra day in your total.

Holiday Settings: Click this to open holiday options. You can choose to skip US holidays and weekends when counting business days. You can also add your own custom holidays by entering a name, month, and day.

Calculate: Press this button to see the total days, business days, weekend days, and holidays between your two dates. You will also see a breakdown in years, months, weeks, hours, minutes, and seconds.

Add / Subtract Tab

Start Date: Pick the date you want to start from.

Operation: Choose Add to move forward in time or Subtract to move backward.

Years, Months, Weeks, Days: Enter how much time you want to add or subtract. You can fill in one field or all of them.

Business Days Only: Turn this on to skip weekends and holidays when counting days and weeks. For a tool focused specifically on business day counting, try our Business Days Calculator.

Calculate: Press this button to see your new resulting date, the day of the week it falls on, and helpful details like whether it lands in a leap year and its ISO week number.

What Is a Date Calculator?

A date calculator is a tool that helps you find the number of days, weeks, months, or years between two dates. It can also add or subtract time from any date to find a new date in the future or past. People use date calculators for many everyday tasks like counting down to a birthday, figuring out how many days until a deadline, or planning a project timeline. If you need to find the exact duration between two specific dates, our Date Duration Calculator is another great option.

How Dates and Time Work

Our calendar is called the Gregorian calendar. Most years have 365 days, but every four years we get a leap year with 366 days. Months have different lengths — some have 30 days, some have 31, and February has 28 or 29. This makes counting days by hand tricky, which is why a calculator is so helpful. If you want to measure the difference between two specific times within a day, check out our Time Difference Calculator or Time Duration Calculator.

Calendar Days vs. Business Days

There are two main ways to count days. Calendar days include every single day — weekdays, weekends, and holidays. Business days only count Monday through Friday and skip weekends. Some people also skip holidays when counting business days. Business day counting is common for work deadlines, shipping times, and legal due dates. Our dedicated Business Days Calculator is built specifically for this type of counting, and our Work Hours Calculator can help you tally up the actual working hours within a given period.

What Are Federal Holidays?

Federal holidays are days set by the U.S. government when most offices and banks are closed. Examples include New Year's Day, Independence Day, Thanksgiving, and Christmas. Some holidays fall on a fixed date every year, while others move around, like Thanksgiving, which is always the fourth Thursday in November. When you exclude holidays from a date calculation, you get a more accurate count of actual working days.

Common Uses for Date Calculations

Project planning: Find out how many working days you have to finish a task. A Business Days Calculator or Lead Time Calculator can help with scheduling and delivery timelines.
Age calculation: See your exact age in years, months, and days. Our Age Calculator is designed specifically for this purpose.
Contract deadlines: Count business days to know when a legal or work deadline falls.
Travel planning: Calculate the length of a trip in days or weeks. You might also find our Flight Time Calculator useful when planning your itinerary.
Pregnancy tracking: Count weeks and days from a specific start date. Our Due Date Calculator and Conception Calculator are built for this exact need.
Loan and interest periods: Find the exact number of days between payment dates. Tools like our Compound Interest Calculator, Simple Interest Calculator, and Loan Calculator can help you work out the financial side of those periods.
Countdowns: Track how many days remain until a special event with our Days Until Calculator.
Work hours tracking: Pair date calculations with our Time Card Calculator to log hours worked over a date range.

Frequently asked questions

Why is my business day count different from my total day count?

Business days only count Monday through Friday. Total days count every day, including weekends. If you also turned on holiday exclusion in the Holiday Settings, those days are removed from the business day count too.

What does the Include End Day option do?

When you turn on Include End Day, the calculator adds one extra day to the total. For example, if you pick January 1 to January 3, the normal count is 2 days. With Include End Day on, it becomes 3 days because January 3 itself is counted.

Can I count days between dates in the past?

Yes. You can pick any two dates, past or future. The calculator will always find the difference between them no matter which direction in time they go.

What happens if my start date is after my end date?

The calculator automatically swaps them so the earlier date comes first. You will still get the correct number of days between the two dates.

How do I exclude holidays from my day count?

Click Holiday Settings below the date fields. Select Do not count holidays. Then check the holidays you want to skip. Press Calculate, and those days will be removed from your business day total.

Can I add my own custom holidays?

Yes. Open Holiday Settings and scroll to the Custom Holidays section. Type a name, pick a month, and pick a day. Click Add More if you need extra rows. You can add up to 20 custom holidays.

What does Business Days Only do in the Add/Subtract tab?

When you turn on Business Days Only, the calculator skips weekends and excluded holidays while counting days and weeks. So if you add 10 business days, it jumps forward 10 weekdays instead of 10 calendar days.

Can I add years, months, weeks, and days all at the same time?

Yes. Fill in any or all of the fields. The calculator adds years and months first, then adds weeks and days after. You can mix and match however you like.

How does the calculator handle leap years?

It uses the Gregorian calendar rules. A year is a leap year if it divides evenly by 4, except for years that divide by 100 unless they also divide by 400. February has 29 days in a leap year. The results panel also tells you if your resulting date falls in a leap year.

What is an ISO week number?

An ISO week number tells you which week of the year a date falls in, based on the international standard. Week 1 is the week that contains the first Thursday of January. The year has either 52 or 53 weeks.

What is Day of Year in the results?

Day of Year shows how many days into the year your date falls. For example, February 1 is day 32 because January has 31 days. The total is out of 365 or 366 if it is a leap year.

Does the calculator account for daylight saving time?

The calculator counts whole calendar days, not hours. Daylight saving time shifts of one hour do not change the day count, so it does not affect your results.

Is there a limit to how far apart the two dates can be?

You can pick dates many years apart. However, for very large ranges over 100,000 days, the business day counting may be capped to keep the tool fast. For most everyday uses, there is no practical limit.

Why do some US holidays show as unchecked by default?

Holidays like Black Friday, Christmas Eve, and New Year's Eve are not official federal holidays. They are included as options because many workplaces observe them, but they are unchecked by default so you can choose which ones matter to you.

Can I use this calculator on my phone?

Yes. The calculator is fully responsive and works on phones, tablets, and computers. All the same features are available on every screen size.