When I calculate one year from today, is today included?

To find one year from today, use the “Add or subtract” tab and move the calendar year by one. Whether today is included does not add or remove a day. When a month or year move lands on a month without the same day, the last day of that month is used. For example, one year after February 29, 2024 is February 28, 2025. “Count the start date” applies only to counting the days between two dates on the “Days between dates” tab.

My result is one day more or less than on another calculator. Why?

The difference comes from whether the start date is counted. semku excludes the start date by default; turn on Count the start date to count it as day 1.

What date is one month after January 31?

If the same day does not exist in the target month, the last day of that month is used: February 28 in 2026, and February 29 in the leap year 2024.

Do business days also exclude holidays, and which ones?

Business days only excludes Saturdays, Sundays and U.S. federal holidays within the supported range under the default working conditions (Mon–Fri). These are the federal holidays for Federal employees as published by OPM, including the Friday observance when a holiday falls on a Saturday; banks, stock exchanges and many private employers use different schedules, and state holidays are not included. If you change the working conditions, the selected weekdays are used and federal holidays and your excluded dates are excluded. The result shows the holiday data version and the supported years.

Can I calculate hours, minutes and seconds?

This page calculates calendar dates only. Elapsed time including the time of day is not supported.

Can I use the working conditions to calculate pay or leave?

The working conditions apply your selected weekdays, federal holidays and excluded dates to count days or find a date before or after. They do not determine actual attendance, pay, leave or legal deadlines. “Count the start date” applies only to days between dates; a business-day move never counts the base date.

Business days calculator

Pick two dates to see the number of days and the counting rule that was applied.

Start date Set to today · editable End date

Count the start date

Business days only

By default the start date is not counted.

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Counting rules in detail

Days between dates are counted on calendar dates, using your device’s local date as today. By default the start date is excluded and the end date included. Turn on “Count the start date” to count it as day 1.

When you move by months or years and the same day does not exist in the target month, the last day of that month is used. For example, one month after January 31, 2026 is February 28; one month after January 31, 2024 is February 29. One year after February 29, 2024 is February 28, 2025.

Under the default working conditions (Mon–Fri, no excluded dates), business days exclude Saturdays, Sundays and the U.S. federal holidays listed in the versioned data — the holidays for Federal employees under 5 U.S.C. 6103 as published by the U.S. Office of Personnel Management (OPM). Federal holidays are not a nationwide day off: many private employers work on Columbus Day and Veterans Day, and when a holiday falls on a Saturday the Friday before is a Federal pay-and-leave day that banks and stock exchanges do not follow. State holidays are not included. If you change the working conditions, the selected weekdays are used and federal holidays and your excluded dates are excluded. Years without holiday data are not estimated; the calculation stops. Legal deadlines may follow different counting rules, so check the relevant regulation or a professional.

A business-day move does not count the base date; it counts only qualifying days starting from the next day in the chosen direction. 0 business days leaves the base date unchanged, and the move works only within the years covered by the holiday calendar.

The default working conditions are Mon–Fri with no excluded dates. If you change them, a business-day calculation excludes each date once, in this order: non-working weekday, federal holiday, your excluded date.

Frequently asked questions

When I calculate one year from today, is today included?: To find one year from today, use the “Add or subtract” tab and move the calendar year by one. Whether today is included does not add or remove a day. When a month or year move lands on a month without the same day, the last day of that month is used. For example, one year after February 29, 2024 is February 28, 2025. “Count the start date” applies only to counting the days between two dates on the “Days between dates” tab.
My result is one day more or less than on another calculator. Why?: The difference comes from whether the start date is counted. semku excludes the start date by default; turn on Count the start date to count it as day 1.
What date is one month after January 31?: If the same day does not exist in the target month, the last day of that month is used: February 28 in 2026, and February 29 in the leap year 2024.
Do business days also exclude holidays, and which ones?: Business days only excludes Saturdays, Sundays and U.S. federal holidays within the supported range under the default working conditions (Mon–Fri). These are the federal holidays for Federal employees as published by OPM, including the Friday observance when a holiday falls on a Saturday; banks, stock exchanges and many private employers use different schedules, and state holidays are not included. If you change the working conditions, the selected weekdays are used and federal holidays and your excluded dates are excluded. The result shows the holiday data version and the supported years.
Can I calculate hours, minutes and seconds?: This page calculates calendar dates only. Elapsed time including the time of day is not supported.
Can I use the working conditions to calculate pay or leave?: The working conditions apply your selected weekdays, federal holidays and excluded dates to count days or find a date before or after. They do not determine actual attendance, pay, leave or legal deadlines. “Count the start date” applies only to days between dates; a business-day move never counts the base date.

Privacy on this page

Calculations run in your browser. The dates, working days and excluded dates you enter are not sent to the server and are not saved in browser storage.

To understand usage and improve the service, this page sends semku’s own usage statistics and automatic error reports to a dedicated endpoint under semku.com/api/telemetry/v1/. They are not used for advertising or third-party tracking.

Usage statistics include the stage of use (such as starting an operation), the time, and fixed identifiers that distinguish the page and feature. The dates you enter and the results shown are not included, not even as hashes or size buckets. Full URLs and search terms are not sent either.

Operations and sessions are distinguished by randomly generated identifiers that exist only in memory while the page is open; they are not stored in cookies or browser storage. No cookie-based or device-fingerprint identification is used.

Error reports include the error type, code and time, and, where available, a registered program-source identifier with line and column numbers. Error message text and stack traces are not sent. Usage statistics and error reports also carry the site identifier, the published version and a random record identifier. Your IP address and user agent are not part of these fields.

If you use the feedback form, pressing Send transmits the rating you chose and the text you typed, together with a random submission ID, the page, site and published version, and the type of request. There are no fields for your name, e-mail address or phone number, and your inputs are not attached automatically. Whatever you type into the free-text field is sent as is — please do not include personal data, passwords, keys or payment details.

Separately, when you access the site, the hosting provider Cloudflare Pages records standard access logs that include your IP address, the time of the request and user-agent information.

For details, see the privacy policy in Korean.

Calculations run in your browser without sending your calculation inputs or results to the server. The counting rule and the holiday data version appear with the result. See “Privacy on this page” for information about access data.