Days until calculator
Choose a date to see right away how many days are left until it, or how many have passed since.
Time since a date
Saved dates
How days are counted and saved
Days are counted from today in Korea Standard Time (KST). If the target date is tomorrow the result is D-1, yesterday D+1 and today D-day. After midnight KST the value changes with the KST date.
This is the difference in days up to the target date. Anniversary or service-day counts that treat the first day (for example the day you met or enlisted) as day 1 may use a different basis.
Time since a date uses the date and time you enter and this device’s clock at calculation time, in this device’s time zone (not KST). It counts complete months, then remaining days, hours and minutes. If a month has no matching day, its last day is used. A blank time means 00:00. Seconds are ignored; daylight saving time changes are not adjusted for.
Saved entries keep the event name and the ISO date in this browser’s local storage. There is no server sync or backup. You can lose the list if you clear browser data, use another browser or device, or if the site address changes. If saving fails, one-off counting still works.
Frequently asked questions
- Is the exam day itself included in the count?
- The target date is D-day and the day before it is D-1. The exam day is not added as day 1. The result is the difference between today’s date and the target date on the KST calendar.
- Why is the result one day more or less than on other calculators?
- A countdown treats today as 0, but anniversary or service-day counts sometimes treat the start date as day 1. semku uses the rule: tomorrow is D-1, yesterday is D+1, today is D-day.
- Can I see the remaining hours as well?
- This page shows the countdown in whole days only. A countdown in hours, minutes and seconds is not supported.
- Does the countdown show on my lock screen?
- No.
Save in this browseris a saved list on this page, not a lock-screen widget. - Can I save several dates with names?
- Yes. Save a name and date for each event, then open or delete them from one list. The list is stored only on this device and in this browser, and is not synced to other devices.
Privacy on this page
Days are counted in your browser using the KST calendar date. The target date and event name you enter are not sent to the server. If you choose to save, the name and date are kept only in this browser’s local storage, with no server sync or backup. Opening a sharing link sends its query string (?d=…, plus &n=… only if you choose to include the event name) to the hosting server as part of the request URL, and it may appear in the server’s access logs. If the name is included, anyone with the link can see it. In contrast, links from the date calculator or Suneung countdown carry the date and a fixed source marker in the #d=…&src=… fragment; this fragment is not included in the request URL and is not sent to the hosting server or its access logs.
To understand how the page is used and to improve the service, this page sends semku’s own usage statistics and automatic error reports. They go only to the dedicated endpoint under semku.com/api/telemetry/v1/. They are not used for advertising or third-party tracking.
The usage statistics include stages of use (such as starting an operation or requesting a copy), the times they occur and fixed identifiers that distinguish the page and feature. They do not include the target date or event name you enter, the saved list, the days shown or the links you copy. Inputs are not sent as hashes or as size categories either. The full URL and search terms are not sent.
Operations and sessions are distinguished by randomly generated identifiers. In the browser, these identifiers exist only in temporary memory and are not written to cookies or browser storage. No identification based on cookies or combined device characteristics is used.
Error reports contain the error type, code and time, and, where available, a registered program-source identifier with line and column numbers. The error message text and stack traces are not sent. Usage statistics and error reports also carry the site identifier, the deployment version and a random record identifier. For access records such as IP addresses, browser signals (User-Agent Client Hints), region and language, see the paragraph below.
The feedback form sends the rating you chose and the text you typed in the free-text field when you press the send button. The form also sends a random ID that distinguishes the submission, along with the page, site, deployment version and type of request. There are no fields for your name, email address or phone number, and the dates or names you enter are not attached automatically. Before sending your text, the widget removes leading and trailing whitespace and, if you selected a rating, adds [+1] or [-1] at the start; it makes no other changes to your text. After receipt, the collector standardizes line endings and removes leading and trailing whitespace. Please do not enter personal data, passwords, authentication keys or payment details.
To improve the service, we record the country and state/province-level region at the time of your visit (an estimate based on the connecting network), which site you came from including the page path, and one display-language setting announced by your browser (for example, en-US). Location is kept to country and region only; no city or precise position is recorded. When you use the service, connection records, including your IP address, are automatically generated and retained to maintain service security and identify abnormal access. Cloudflare is the data processor for this site. Collection of this item is enabled only after this notice is published; we do not collect it retrospectively for use before collection is enabled. Query strings such as search terms are not recorded, and neither is the full list of preferred languages or the raw request headers. Collection of this information is currently disabled and will only be enabled after this notice is published. If we enable collection, we will collect and use signals your browser reports about its type and version, along with an indication of whether automation tools are being used, to identify bots. These browser signals are estimates and do not conclusively identify your browser's type or version or whether automation tools are being used. We do not collect it retrospectively for use before collection is enabled. The raw User-Agent request header is not recorded. These records are per visit only and use no identifier that links one visit to another. Recording starts only with visits after this notice is published and is not applied retroactively to earlier visits. The region and the referring site have been recorded since 2026-09-20; the display language since 2026-09-24. Browser signals are not recorded yet.
Separately, when you visit the site, the hosting provider records your IP address, the time of the request and user-agent information about your browser and device in Cloudflare Pages’ standard access logs.
For details, see the privacy policy.
Calculations use the KST calendar date in your browser; saved events stay in this browser, without server sync or backup. Opening a sharing link sends its query string (?d=…, plus &n=… only if you include the event name) to the hosting server, where it may appear in access logs and the name is visible to anyone with the link; the #d=…&src=… fragment in links from the date calculator or Suneung countdown is not sent to the server or its access logs.