Introduction
The 180 Day Calculator tells you the exact date 180 days from any day you pick. Type a start date, and the tool shows the end date, the day of the week, and how many weeks and months that span covers.
You can use it three ways:
- Add 180 days to find a future date.
- Subtract 180 days to find a past date.
- Track a deadline to see how many days are left in a 180-day window.
People use 180-day counts all the time. Contracts, visas, warranties, court filings, return windows, and loan terms often run 180 days. Counting that by hand is slow and easy to get wrong, since months have different lengths and leap years add a day.
The calculator handles the month lengths and leap days for you. You can also switch to business days only if weekends don't count, pick your date format (US, EU, or ISO), and read a step-by-step solution that shows how the math works. A quick reference table also lists common dates like 30, 60, 90, and 180 days from today.
How to use our 180 Day Calculator
Pick a start date, choose how you want the days counted, and the calculator shows you the date 180 days later or earlier, the day of the week, and a full step-by-step breakdown.
Date display format: Choose MM/DD/YYYY, DD/MM/YYYY, or YYYY-MM-DD. This changes how every date box and every result is shown.
Tab choice: Click "Add 180 Days" to count forward, "Subtract 180 Days" to count back, or "Deadline Tracker" to watch a 180-day window that is already running.
MM, DD, and YYYY boxes: Type your start date here, one part in each box. The boxes move into the order you picked above.
Calendar picker: Instead of typing, click the picker and choose your date from a calendar. The MM, DD, and YYYY boxes fill in for you.
Count business days only: Turn this on to skip weekends, so the 180 days are work days. Leave it off to count every calendar day.
Include Saturdays as business days: Turn this on if your work week runs Monday to Saturday. It only works when business day mode is on.
Label (Deadline Tracker only): Type a short name, like "Visa Expiry" or "Warranty Period," so you know which deadline the results belong to. This is optional.
Calculate button: Click it to see the end date, the day of the week, span stats, a timeline, and the math steps.
Reset to Today, Clear, and Repeat buttons: "Reset to Today" puts today's date back in. "Clear" empties the boxes. "Repeat" adds or subtracts another 180 days from your last answer.
What Is a 180-Day Period?
180 days is about six months, or a little over 25 weeks. Many rules, contracts, and deadlines use this exact number of days instead of "six months" because days are easy to count and never change length. Six months can mean 181 days or 184 days depending on which months you cross. 180 days always means 180 days.
How Counting 180 Days Works
Counting starts the day after your start date. If your start date is Day 0, then the next day is Day 1, and Day 180 is your end date. This is called "exclusive" counting, and it is the way most contracts, courts, and government forms count days.
Going backward works the same way. If you know your deadline and want to know when the 180-day clock started, you count 180 days back from that date.
Calendar Days vs. Business Days
- Calendar days count every single day, including Saturdays, Sundays, and holidays. Most legal and medical deadlines use calendar days.
- Business days skip weekends. 180 business days is much longer than 180 calendar days (about 36 weeks, or over eight months). Some banks, shipping rules, and work contracts use business days.
Always check which kind your rule uses. The difference is more than two months.
Leap Years and February 29
A leap year adds February 29 to the calendar. If your 180-day span crosses that date, that day counts as one of your 180 days. This shifts your end date by one day compared to a normal year. Leap years happen in years divisible by 4, except century years that are not divisible by 400. So 2024 and 2028 are leap years, and 2000 was one, but 1900 was not.
Where 180-Day Deadlines Show Up
- Visas and travel: Many tourist visas and passport rules use 180-day windows, like the Schengen 90/180 rule.
- Real estate: A 1031 exchange in the U.S. gives you 180 days to close on a replacement property.
- Legal claims: Some job discrimination complaints must be filed within 180 days.
- Warranties and returns: Many product warranties and store policies last 180 days.
- Contracts and notice periods: Leases, loans, and job contracts often use 180-day notice or waiting periods.
- Health and fitness: Training plans, medical follow-ups, and recovery timelines often run 180 days.
Handy 180-Day Facts
- 180 days = 25 weeks and 5 days
- 180 days ≈ 5.9 months (using an average month of 30.44 days)
- 180 days = 4,320 hours
- 180 days is just under half a year (a year is 365 days)
- The day of the week always shifts forward by 5 days, since 180 ÷ 7 leaves a remainder of 5. A Monday start lands on a Saturday.
Watch Out for Weekend End Dates
If Day 180 lands on a Saturday or Sunday, many offices and courts are closed. Some rules let you move the deadline to the next business day, but not all of them do. Check your contract or agency rule before you assume you get extra time. It is safer to act early than to miss a deadline by one day.