|Ab urbe condita||2654|
|British Regnal year||64 Vict. 1 – 1 Edw. 7|
庚子年 (Metal Rat)
4597 or 4537
— to —
辛丑年 (Metal Ox)
4598 or 4538
|- Vikram Samvat||1957–1958|
|- Shaka Samvat||1822–1823|
|- Kali Yuga||5001–5002|
|Julian calendar||Gregorian minus 13 days|
|Minguo calendar||11 before ROC
|Thai solar calendar||2443–2444|
1901 (MCMI) was a common year starting on Tuesday (dominical letter F) of the Gregorian calendar and a common year starting on Monday (dominical letter G) of the Julian calendar, the 1901st year of the Common Era (CE) and Anno Domini (AD) designations, the 901st year of the 2nd millennium, the 1st year of the 20th century, and the 2nd year of the 1900s decade. As of the start of 1901, the Gregorian calendar was 13 days ahead of the Julian calendar, which remained in localized use until 1923.
The date of Friday December 13 20:45:52 1901 is significant for modern computers because it is the earliest date representable with a signed 32-bit integer on systems that reference time in seconds since the Unix epoch. This corresponds to -2147483648 seconds from Thursday January 1 00:00:00 1970. For the same reason, many computers are also unable to represent an earlier date. For related reasons, many computer systems suffer from the Year 2038 problem. This is when the positive number of seconds since 1970 exceeds 2147483647 (01111111 11111111 11111111 11111111 in binary) and wraps to -2147483648. Hence the computer system erroneously displays or operates on the time Friday December 13 20:45:52 1901. In this way, the year 1900 is to the Year 2000 problem as the year 1901 is to the Year 2038 problem.