Plan 2–3 days in Varanasi to see the main ghats, temples and Ganga rituals. Allow 3–4 days if you also want to visit Sarnath or explore at a slower pace. The most comfortable time to visit is generally October to March.
Practical tip: Festivals such as Dev Deepawali and major Hindu holidays can make Varanasi especially atmospheric but also crowded and more expensive. Book accommodation and transport early if your dates coincide with a festival.