What this calculator does
How many days in a year sounds like it should always have the same answer, but it does not: most years run to 365 days, while leap years run to 366. This calculator takes any date, works out whether that year is a leap year, and shows the day count for both the year and the specific month the date falls in.
The same question comes up in a narrower form too, such as how many days in February, which is the one month where the answer genuinely changes from year to year. Rather than memorising the leap year rule, entering a date here shows the day count directly, along with how many days are left in the year and in the month from that point.
The formula
A year is a leap year if it divides evenly by 4, unless it also divides evenly by 100, in which case it is not a leap year, unless it also divides evenly by 400, in which case it is one after all. The days remaining in the year and month are counted forward from the date entered.
| Term | Meaning |
|---|---|
| Leap year | A year with an extra day, 29 February, added to keep the calendar aligned with the Earth’s orbit. |
| Day of the year | The date’s position counting from 1 January, from 1 to 365 or 366. |
The inputs explained
| Field | What to enter |
|---|---|
| Any date in the year and month to check | Any date in the year and month you want to check. The default is today. |
When to use it
Working out how many days left in the year
Budgets, subscriptions and project deadlines are sometimes tracked against the number of days left in the calendar year, which this calculator reads off directly rather than requiring a manual count.
Checking whether a specific year is a leap year
Payroll, interest and lease calculations that count actual days in a year need to know whether it is 365 or 366 days long, and the century exception (1900 was not a leap year, 2000 was) catches people out often enough to be worth checking rather than assuming.
Planning around February
A February birthday or anniversary on the 29th only falls on the actual date once every four years; checking the day count in February for a given year shows whether it is a 28 or 29 day month.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How days remaining in the year fall as the date moves through it
The same check run against a series of dates spaced through the year.
| Date checked | Days in the year | Day of the year | Days remaining in the year |
|---|---|---|---|
| today | 365 | 225 of 365 | 140 |
| today+30 | 365 | 255 of 365 | 110 |
| today+60 | 365 | 285 of 365 | 80 |
| today+90 | 365 | 315 of 365 | 50 |
| today+180 | 365 | 40 of 365 | 325 |
| today+300 | 365 | 160 of 365 | 205 |
The leap year rule in practice, including the century exception
A run of years chosen to show all three cases of the leap year rule.
Questions
How many days are in a leap year?
366, with the extra day added as 29 February. Every other detail of the calendar, including which day of the week each date falls on afterwards, shifts by one day compared with a non-leap year.
How many days in February?
28 in an ordinary year, 29 in a leap year. Entering any date in February shows which applies for that particular year, alongside the day count for the year as a whole.
How many days left in the year does this show?
It shows the whole days remaining after the date entered, counting forward to 31 December, so checking today’s date gives a live count of what is left in the current year.
Why is 1900 not a leap year but 2000 was?
Century years only count as leap years if they divide evenly by 400. 1900 divides by 100 but not by 400, so it was skipped; 2000 divides evenly by both, so it kept its extra day.
To count the exact number of days between two specific dates, see the days between dates calculator. For a date’s weekday and week number instead, use the day of the week calculator.