Date Calculator
Pick a calculation mode on the left and enter your dates, and the total days and span, or the shifted date, appear on the right instantly with no calculate button.
Input
Enter a start and end date and the period is calculated automatically.
Result
- Total days
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- Span (Y·M·D)
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- Weeks
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- Business days
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- From today
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- Countdown
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Dates are calculated as calendar dates in your browser local time, without time zones. Month and year math clamps to the last day of the month, and holiday skipping uses the tool's registered U.S. federal holidays (2024–2027, observed weekend shifts included). Bank and market holidays may differ; confirm important legal or filing deadlines against official sources.
ready to use.
- Visible firstKeep the input and result positions clear.
- Results firstPut the main number up front and keep the process secondary.
- Less to askNo sign-up or extra information before using the tool.
How to use the date calculator for two different problems
This date calculator handles two different date problems on one screen. One is "how far apart are two dates," and the other is "what date is a number of days, weeks or months before or after a given day." Choose a mode on the left and enter your dates; the result on the right updates instantly with no calculate button, so you can set deadlines, business days, anniversaries and billing dates quickly.
The period mode shows the total number of days along with a years-months-days breakdown and a week count, and lets you count the end date or skip weekends and holidays. The add and subtract mode moves a base date by days, weeks, months or years, and month and year math clamps to the last day of the month. Holiday skipping uses U.S. federal holidays as a reference set, so confirm anything time-critical against official sources.
What this calculator answers
The two modes answer different questions. Switching modes at the top changes the inputs and the result to match.
- Period: total days, plus a years-months-days breakdown and a week count
- Business days: working days with weekends and holidays removed (optional)
- Add / subtract: the date after moving a base date by days, weeks, months or years, plus its weekday
- Distance from today: how many days after or before today the result is, with a countdown
How to use it
There is no calculate button. The result updates the moment your inputs are valid.
- Pick "Days between" or "Add / subtract" at the top.
- For days between, enter a start and end date; for add/subtract, enter a base date and the direction (+/−), amount and unit.
- Turn on Include end date, Skip weekends or Skip holidays if you need them.
- Use Copy result to grab the text, and Reset to return to an empty state.
How days between two dates are counted
The default is "end date minus start date." For example, the 1st to the 31st counts as 30 days. The same date is 0 days, and an end date before the start date is flagged as an error. The total is shown along with a years-months-days breakdown and a week count.
- Total days = end date − start date (the end day is not counted by default)
- Years-months-days = the real calendar span, with end-of-month clamping
- Weeks = the total days divided by 7, plus the remaining days
- Same date is 0 days; an earlier end date is not calculated
When to turn on "Include end date"
Turn it on when the last day should be part of the range. This adds one day to the total. It fits rentals, hotel stays and usage periods where both the first and last day count.
- Off (default): the 1st to the 5th = 4 days (intervals or nights)
- On: the 1st to the 5th = 5 days (calendar days)
- Hotel nights usually use off; rental or assigned work days use on
Business days: weekends and U.S. federal holidays
Skip weekends removes Saturdays and Sundays, and Skip holidays removes the registered U.S. federal holidays. Together they approximate real working days. This tool uses federal holidays with their observed weekend shifts; note that banking and stock-market calendars can differ from the federal list.
- Skip weekends: removes every Saturday and Sunday
- Skip holidays: removes U.S. federal holidays, including observed dates when a fixed holiday falls on a weekend
- The business-day count follows your "Include end date" setting
- Confirm court, bank or filing deadlines against the relevant official calendar
Add / subtract and end-of-month clamping
The base date moves by days, weeks, months or years. For months and years, if the target month has no matching day, the result clamps to the last day of that month. In days you can turn on skipping weekends and holidays to move on a business-day basis.
- Jan 31 + 1 month = Feb 29 in a leap year, or Feb 28 otherwise
- Feb 29 + 1 year = Feb 28 next year, and Feb 29 again on the next leap year
- Weeks and days move by exactly 7 days and 1 day
- Days + "skip weekends & holidays" counts only business days
A worked example
Here are both modes in the same units and format the screen uses. The period runs from 2024-01-15 to 2024-07-16, and the add example takes one month after 2024-01-31.
- Period · start date
- 2024-01-15
- Period · end date
- 2024-07-16
- Total days
- 183 days
- Span (Y·M·D)
- 6 months 1 day
- Weeks
- 26 weeks 1 day
- Add · Jan 31 + 1 month
- 2024-02-29 (Thursday)
Common mistakes
Checking these before you rely on a result avoids off-by-one errors and wrong baselines.
- Mixing in time: this tool counts dates only, not clock time or time zones.
- Include vs exclude: if the result is off by a day, check "Include end date" first.
- Holiday range: dates outside 2024–2027 or one-off closures may be missed.
- Month expectations: month math clamps, so "+1 month" is not always the same day number.
Checklist before you use the result
For important dates, lining these up means less recalculating later.
- The mode matches your goal (period vs add/subtract)
- The Include end date setting matches how you count (nights vs days)
- If you need business days, weekend and holiday skipping are both on
- The end-of-month clamp on a month/year result is what you intended before copying
Date calculator FAQ
What is the difference between including and excluding the end date?
Excluding (the default) counts "end date minus start date," while including adds one day so both the start and end date are counted. For example, the 1st to the 5th is 4 days excluded and 5 days included. Hotel nights usually exclude the end date, while rental or usage days include it.
Can I skip weekends and holidays at the same time?
Yes. Turn on both Skip weekends and Skip holidays to count business days with Saturdays, Sundays and the registered U.S. federal holidays removed. The holiday set covers 2024–2027 as a reference; for other years or one-off closures, confirm separately.
What is January 31 plus one month?
If the target month has no matching day, the result clamps to the last day of that month. So January 31 plus one month is February 29 in a leap year and February 28 otherwise. Years follow the same rule, so February 29 plus one year is February 28 the next year.
Which holidays are included?
The tool uses U.S. federal holidays for 2024 through 2027, including the observed date when a fixed holiday lands on a weekend. Dates outside that range are treated as regular weekdays, so long-range future business-day counts are approximate. Bank and stock-market holidays can differ from the federal list.
My result is off by a day from another calculator.
Most often this is the "Include end date" setting. If the other calculator counts both the start and end date, turn on Include end date here to match. If it still differs, check whether that tool counts clock time as well, or uses a different holiday set.
Reference date: 2026-07-17. Date math uses the Gregorian calendar, and holidays are the U.S. federal holidays for 2024–2027 (with observed weekend shifts). Business-day and holiday results are for reference; bank and market calendars may differ.