The Day of the Programmer is held on the 256th day of the year, a date chosen because 256 is a number every developer recognizes. In a normal year that is September 13; in a leap year it moves to September 12. The next Programmers’ Day falls on Monday, September 13, 2027, and the live countdown above is already ticking toward it.
Why the 256th day?
256 is 2 to the power of 8, which is the number of distinct values a single byte can hold, from 0 to 255. In hexadecimal it is written 0x100, a satisfyingly round number. It is also the largest power of two that is smaller than the number of days in a year, so it always fits on the calendar.
How the date is calculated
Counting from January 1 as day 1, the first eight months of a common year contain 243 days. Add 13 and you reach day 256: September 13. In a leap year, February has 29 days, which pushes everything forward by one, so day 256 lands on September 12. The leap year rules matter here:
- A year divisible by 4 is a leap year, so the day falls on September 12.
- Century years such as 2100 are not leap years unless they are divisible by 400, so they keep September 13.
- All other years are common years, with the Day of the Programmer on September 13.
Yes, that is the kind of edge case programmers enjoy, and the countdown on this page already handles it for you.
Where the day comes from
The idea came from Russia. In 2002 Valentin Balt and Michael Cherviakov, who worked at the company Parallel Technologies, started collecting signatures to ask the government to recognize a professional holiday for programmers. On September 11, 2009, President Dmitry Medvedev signed a decree making the Day of the Programmer an official professional day in Russia. Developers in many other countries have since adopted the date informally.
China’s tech community has its own version on October 24, written 10/24. The number 1024 is 2 to the power of 10, the number of bytes in a kibibyte.
Ways to celebrate
- Thank a maintainer: send a kind note, open a helpful issue or sponsor an open source project you rely on.
- Ship something small: finish the side project that has been sitting at 90 percent for months.
- Learn a new tool: try a language, framework or editor shortcut set you have been curious about.
- Pair with a beginner: mentoring a junior developer or a student for an hour can make their year.
- Host a team retro with snacks: celebrate what went well, then clean up one piece of tech debt together.
- Order a 256-themed treat: some teams bring a cake with 0x100 or 11111111 + 1 written on top.
More dates for your dev calendar
Pi Day on March 14 is a favorite in engineering teams, System Administrator Appreciation Day falls on the last Friday of July, and Ada Lovelace Day on the second Tuesday of October celebrates women in science and technology. Want to remind the team? Share this countdown in your Slack channel or embed it on your company’s internal dashboard.