How many days are in December

December has 31 days. It is the final month of the Gregorian calendar and one of seven months with this length. Whether the year is common or leap, December always runs from 1 December through 31 December.

For Australians, December is a busy summer month shaped by school holidays, Christmas preparations, travel, end-of-year work deadlines and public holidays. Knowing the exact number of days makes it easier to plan schedules, calculate date differences and check how many weekdays remain before the year ends.

December has 31 days

The calendar sequence in December is:

• 1 December
• 2 December
• 3 December
• …
• 30 December
• 31 December

Because the month contains 31 dates, the next day after 31 December is 1 January of the following year. This makes December a useful reference point when calculating the number of days between two dates or working out a countdown to New Year’s Day.

December is also a 31-day month in leap years. Leap years add an extra day to February, changing it from 28 to 29 days, but they do not alter the length of any other month. For example, December 2024 and December 2025 both contain 31 days.

Why December always has 31 days

The modern month pattern comes from the Gregorian calendar, which is used in Australia and most countries. The calendar divides the year into 12 months with lengths of 28, 29, 30 or 31 days. December is one of the months assigned 31 days, alongside January, March, May, July, August and October.

A leap year occurs when the year is divisible by four, except for century years that are not divisible by 400. This rule keeps the calendar aligned with the Earth’s orbit around the Sun. It affects February only, so checking whether a year is a leap year is unnecessary when asking how many days are in December.

For a more precise result, a date calculator can count the days elapsed between two December dates. Depending on the calculation method, the starting date may or may not be included, so it is important to check whether the result is inclusive or exclusive.

December dates in Australia

December falls during summer in Australia. Sydney and Brisbane often experience warm or humid conditions, while Melbourne can shift quickly between hot days and cooler weather. Perth and Adelaide commonly plan outdoor events around long daylight hours, and many people travel to beaches, parks or regional areas during the school holiday period.

Christmas Day is 25 December, followed by Boxing Day on 26 December. Public holiday arrangements can vary between states and territories, particularly when a holiday falls on a weekend and a substitute day is observed. Under Australia’s Fair Work system, public holiday and annual leave rules affect rostering, pay and workplace closures, while awards and employment agreements may add further detail.

Retail trading laws also differ around the country. Shops in central Sydney, Melbourne shopping precincts and major suburban centres may use extended December hours, whereas smaller retailers can close earlier. Businesses should check the relevant state or territory rules rather than assuming that every day in the 31-day month is an ordinary trading day.

Using December for planning

A simple month view helps separate calendar days from working days. In a typical Monday-to-Friday schedule, December may contain between 20 and 23 weekdays, depending on which day of the week 1 December falls on. Christmas Day, Boxing Day and substitute public holidays can reduce the number of standard business days further.

This distinction matters for payroll, invoices, deliveries and project deadlines. A business that promises delivery within five business days should exclude weekends and applicable public holidays, rather than counting five consecutive dates. Australian employers also need to consider approved annual leave, workplace shutdowns and any applicable modern award when planning the final working weeks of the year.

December is useful for personal countdowns too. You can calculate the days until a flight, family gathering, bill due date or New Year event by entering the relevant dates into a calendar tool. For people tracking a night-sky event during the month, a Leaf Moon checklist can pair a date countdown with practical viewing preparation.

Practical checks for December dates

The following habits reduce common calendar mistakes when organising Australian summer plans, work commitments or end-of-year records:

• Confirm that the date is in December rather than January when a countdown crosses midnight on New Year’s Eve.
• Count 31 calendar dates, but remove weekends and public holidays when estimating business days.
• Check the public holiday calendar for your state or territory, especially when Christmas Day or Boxing Day falls on a weekend.
• Allow for school holiday traffic when planning road trips from Melbourne, Sydney, Brisbane, Perth or other major cities.
• Review retailer, courier and supplier opening hours before scheduling purchases or deliveries.
• Use the exact year in a date calculation, even though December always has 31 days, because the weekday pattern changes annually.

A December calendar can also clarify recurring tasks such as rent payments, subscription renewals, stocktake, timesheet submission and annual leave records. When a deadline is described as “by the end of December”, the final possible calendar date is 31 December, although a workplace may require completion on the last business day before the holiday break.

December’s fixed length makes many calculations straightforward: 31 days, 744 hours, or 44,640 minutes in a standard 24-hour calculation. These figures describe elapsed calendar time and do not account for daylight saving changes, which affect local clock time in jurisdictions such as New South Wales, Victoria, Tasmania, South Australia and the Australian Capital Territory.

Use the 31-day length of December as the starting point for accurate planning, then adjust for weekends, public holidays, local trading rules and the specific year. Check the calendar for the dates that matter most, and use a date calculator when an exact business-day or countdown result is required.