Date Calculator
Find the exact number of days, weeks, months, and years between two dates, add or subtract time from any date, or count down the days until a future date. Includes a business-days-only option and works with date formats worldwide.
Choose what you want to do — measure the gap between two dates, add/subtract time from a date, or count the days until a future date. Toggle "business days only" to exclude weekends.
* Date calculations use the standard Gregorian calendar and account for leap years automatically. "Business days" excludes Saturdays and Sundays but not public holidays, which vary by country — adjust manually for local holidays. Time-zone differences are not applied.
Popular Countdowns
Tap any of these to instantly count the days from today:
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What Is a Date Calculator?
A date calculator is a free online tool that measures time between dates and shifts dates forward or backward. It answers three of the most common date questions instantly: how many days are between two dates, what date falls a certain number of days from now, and how many days until an upcoming event. No manual counting on a calendar, no off-by-one errors, and leap years are handled automatically.
Our date calculator covers all three jobs in one place. It shows the gap in days, weeks, months, and years, lets you add or subtract years/months/days from any starting date, counts down to a future date, and can restrict the count to business days only (excluding weekends) — useful for project deadlines, contract terms, notice periods, and shipping estimates.
How to Use This Date Calculator
- Pick a mode — days between two dates, add/subtract time, or days until a future date.
- Enter your date(s) — use the date picker; it accepts the format used by your device and region.
- Choose your counting options — include or exclude the end date, and count all days or business days only.
- Click Calculate — and you'll see the total days, the breakdown in weeks/months/years, and the resulting date where relevant.
How to Calculate the Number of Days Between Two Dates
The simplest way is to convert each date to a day count and subtract. Computers do this by counting days from a fixed reference point, which sidesteps the tricky parts — different month lengths and leap years. By hand, you'd count the remaining days in the start month, add the full months in between, and add the days in the final month.
(Add 1 if you want to include both the start and end days)
Example: From January 1 to January 31 is 30 days if you exclude the end date, or 31 days if you include both endpoints. Whether to include the end date depends on what you're measuring — a hotel stay counts nights (exclude), while "how many days do I have to finish" often counts both (include).
What Are Business Days?
Business days (or working days) are the days companies, banks, and courts normally operate — typically Monday through Friday, excluding weekends. They're the standard unit for shipping times, payment processing, legal notice periods, and project schedules. Our calculator's business-days option automatically skips Saturdays and Sundays. Note that public holidays differ by country, so subtract any local holidays manually for an exact figure.
If you're counting working days to plan income or pay periods, our Paycheck Calculator helps you turn those days into take-home figures.
How Many Days Until…? Using the Countdown Mode
The "days until" mode counts from today to any future date — perfect for deadlines, holidays, birthdays, weddings, exams, or product launches. Switch to countdown mode, pick your target date, and you'll see exactly how many days (and business days) remain. For a recurring milestone like a birthday, our Age Calculator also shows the countdown to your next one along with your precise age.
Common Uses for a Date Calculator
| Use Case | Mode | Tip |
|---|---|---|
| Project deadline planning | Add/subtract days | Use business days to skip weekends |
| Contract or notice period | Add days to a start date | Check whether the end date is included |
| Shipping / delivery estimate | Add business days | Add extra days for local holidays |
| Countdown to an event | Days until | Great for weddings, exams, launches |
| Age or anniversary in days | Days between | See our Age Calculator for precision |
| How long ago something happened | Days between | Put the past date as the start |
Leap Years and Why They Matter
A leap year adds February 29, making the year 366 days instead of 365. Leap years occur every 4 years, except century years not divisible by 400 (so 1900 was not a leap year, but 2000 was). Counting days across a February 29 by hand is a common source of errors — our calculator accounts for leap years automatically, so date differences spanning multiple years are always exact.