Last updated: October 2026
180 days from today
180 days is 25 weeks and 5 days — just under 6 months (5.9, to be precise). It's one of the most-searched date questions because the number shows up everywhere: 180-day return and warranty windows, project timelines, and immigration rules built around 180-day stays. Counting it by hand means hopping across five or six month boundaries with different lengths; the preset above does it in one tap, and the result includes the day of the week so you know whether your deadline lands on a weekend.
12 weeks from today
Twelve weeks is the classic planning block — the "12-week year" for goals, a full fitness program, an academic quarter, a product sprint cycle. Because 12 weeks is an exact multiple of 7, the resulting date always falls on the same weekday as today. The calculator's week unit handles the conversion, and the Add/subtract mode shows how far the result is from today in days and weeks.
Days until a date — countdown
"How many days until…" is the other half of date math — weddings, launches, exams, holidays, product releases. Enter the date once and the ticker updates every second, so the number is never stale. The result also names the weekday of your target date, which matters when you're counting down to something like a Saturday wedding or a Monday launch. If the date has already passed, the calculator tells you instead of showing a negative number.
How many days between two dates
The only real decision in date subtraction is whether the endpoints count. Hotel nights, rental days and age calculations exclude one endpoint (October 8 to October 9 is 1 night); project plans and "days until" counts often include both (October 8 to October 9 is 2 days on the plan). The calculator defaults to excluding the end date — the standard convention — and the checkbox flips it. Results also show the breakdown in weeks, approximate months and years, plus the weekday of each date. Doing it in a spreadsheet instead? Put the start date in A2 and the end date in B2, then use =B2-A2 formatted as a number.
How many days are in each month
| Month | Days | Month | Days |
|---|---|---|---|
| January | 31 | July | 31 |
| February | 28 (29 in leap years) | August | 31 |
| March | 31 | September | 30 |
| April | 30 | October | 31 |
| May | 31 | November | 30 |
| June | 30 | December | 31 |
A year is a leap year if it's divisible by 4 — except century years, which must be divisible by 400. That's why 2024 had a February 29 but 2026 doesn't, and why 2000 was a leap year but 1900 wasn't (see leap year rules). The calculator handles all of this automatically: add one month to January 31 and it correctly lands on February 28 (or 29), never March 3.