How long is the Sandakphu trek?

Sandakphu is a trekkers' paradise. It is the highest point of West Bengal at 11926 ft in the district of Darjeeling and provides vistas of the world's tallest peaks- Everest, Kanchenjunga, Makalu, and Lhotse. This trek takes you along India's and Nepal's borders. You can travel in and out of Nepal regularly during this trek.
Sandakphu Trek means "Height of the Poison Plant," an allusion to the abundance of toxic aconite plants that grow near the peak. Sandakphu is the highest mountain in the Singalila range, a notable jut of high ground at the southern end of a long crest that flows down from the Kanchendzonga range and the endpoint of numerous trekking routes in the Darjeeling-Sikkim region.
The best views in the Himalayas are unavoidably obtained from higher elevations, but this trip up this ridge passes through small communities, which is one of the most scenically gratifying in the Himalayas. The well-known "Sleeping Buddha" peak formation is a must-see for everyone. Most portion of this trekking route is within the Singalila National Park. 
This area is a biodiversity hotspot in the eastern Himalayas and home to the endangered red panda, various bird species, and spectacular alpine vegetation, such as the ever-present rhododendrons, towering fir, birch, bamboo trees, etc. Sandakphu trek is a great choice to start if you're new to trekking, and this trek is suitable for both experienced and beginner hikers. 
Maneybhanjan, located around 25 km from Darjeeling, is the gateway to the Sandakphu region at an altitude of 2134 meters. Maneybhanjang to Sandakphu is approximately 31 kilometres apart. The trip could take three days to complete. You can continue your hike from Sandakphu to Phalut or descend to Rimbik, there are various alternatives for this, and the trek can be completed within four days.