The definitive answer: 1901 CE (1958 BS) — and the fascinating story behind Nepal's calendar change
Nepal officially adopted Bikram Sambat (BS) as its national calendar in 1901 CE (1958 BS). The decision was made by Prime Minister Chandra Shumsher Rana, who established the Vikram Samvat era as the country's legal and administrative calendar. Before this, Nepal had used the Shaka Sambat (Saka era) for official purposes, alongside the culturally significant Nepal Sambat. This article traces the complete timeline of how Bikram Sambat became Nepal's official calendar, the historical context of the decision, and what calendars preceded it.
In 1901 CE — which corresponds to the Bikram Sambat year 1958 — Prime Minister Chandra Shumsher Rana (r. 1901–1929) issued a decree replacing the Shaka Sambat with Vikram Samvat (Bikram Sambat) as the official calendar of the Kingdom of Nepal. The new year that year (Baishakh 1, 1958 BS) was declared a public holiday, and all government documents, court records, and legal procedures were required to use BS dates moving forward.
Why 1901? This was the year Chandra Shumsher came to power after assassinating his predecessor (and uncle), Prime Minister Dev Shumsher. As part of his sweeping administrative reforms, he standardized the calendar across the kingdom, choosing the Vikram Samvat — a calendar with deep Hindu prestige — over the existing Shaka era.
However, the implementation was gradual. Official documents continued to show both Shaka and Vikram years for a short transition period, but by 1903 CE (1960 BS), Bikram Sambat had fully superseded the Shaka era in all government use.
Nepal has a rich history of multiple calendar systems. Understanding what came before Bikram Sambat helps explain why the change was significant.
The Shaka era (beginning in 78 CE) had been used in Nepal for official purposes since the time of Prithvi Narayan Shah. However, Prime Minister Chandra Shumsher had several motivations for the switch:
Notably, Nepal Sambat — which had lost official status under the Shahs — was not revived at this time. The Ranas considered Nepal Sambat (a lunar calendar of 354 days) impractical for government administration because it would require frequent intercalary months to keep pace with the seasons.
Although Bikram Sambat was not the official state calendar before 1901, it was never absent from Nepali life. During the Licchavi period (c. 4th–8th century CE), several stone inscriptions recorded dates in the Vikram Samvat era. The Malla kings also used BS alongside Nepal Sambat for certain temple construction records. And for centuries, astrologers (Jyotish) and priests relied exclusively on Bikram Sambat to determine festival dates, auspicious timings, and horoscopes. Thus, the 1901 adoption formalized what was already deeply embedded in Nepali religious and cultural practice.
For a deeper dive into the calendar's ancient roots, read our article: History of Bikram Sambat →
Chandra Shumsher Jung Bahadur Rana (1863–1929) was the fifth Prime Minister of Nepal from the Rana dynasty, serving from 1901 to 1929. He is best known for modernizing Nepal's infrastructure (building roads, hospitals, and schools) and for his ruthless rise to power — he reportedly executed his predecessor, Dev Shumsher, along with dozens of other relatives. His decision to adopt Bikram Sambat was part of a broader Hinduization campaign, which also included constructing temples and promoting orthodox Hindu practices.
Ironically, while Chandra Shumsher is remembered for his iron-fisted rule, the calendar he imposed has outlasted his dynasty by over half a century and remains Nepal's official calendar to this day.
Changing a nation's official calendar was a massive administrative undertaking in 1901. The steps included:
By 1903 CE (1960 BS), the transition was complete, and the Shaka era was officially retired from government use. (Nepal Sambat continued informally among the Newar community.)
| Calendar | Epoch Start | Year at Adoption (1901 CE) | Status pre-1901 |
|---|---|---|---|
| Shaka Sambat | 78 CE | 1823 Shaka | Official state calendar (since 1769) |
| Bikram Sambat | 57 BCE | 1958 BS | Used culturally & religiously, not official |
| Nepal Sambat | 879 CE | 1022 NS | Traditional calendar of Newar community, official during Malla period |
After 1901, Bikram Sambat became the sole official calendar. Nepal Sambat was later recognized as a national calendar in 2007 CE but does not replace BS for legal purposes.
The decree was issued shortly after Chandra Shumsher became Prime Minister in June 1901 (Ashadh 1901 CE). The official change took effect on Baishakh 1, 1958 BS (mid-April 1901 CE), marking the start of the new BS year.
India uses the Shaka calendar for certain government purposes (like the Gazette of India), but Nepal's Rana rulers wanted a distinctly Hindu calendar associated with Vikramaditya rather than the Sakas.
Yes, for international business, travel, and diplomacy, Nepal uses AD alongside BS. However, all official Nepali documents and legal proceedings use BS dates. Our BS to AD converter helps navigate between them.
There were discussions among the Ranas about reviving Nepal Sambat, but its shorter lunar year (354 days) was deemed impractical for tax collection and record-keeping, so Bikram Sambat was chosen instead.
Knowing the adoption date is just the start. For practical use — from verifying a birth certificate to planning a festival — you need an accurate BS to AD converter. Our tool handles all historical and modern dates correctly, including the Adhik Maas (intercalary month).
Continue exploring the fascinating history and significance of Nepal's official calendar:
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