The main reason you need to prebook tickets for Windsor Castle in advance is to avoid waiting in line at the entrance. During the summer months, Windsor Castle gets really busy, and you can wait up to 1 hour to enter the complex. The advantage of prebooking tickets is that it guarantees fast track, skip the line entry.

In 2026, it is highly recommended to book Windsor Castle tickets in advance online to guarantee entry and avoid potentially long queues. While the Royal Collection Trust still allows walk-up purchases at the Admissions Center on the day of the visit (subject to availability), the castle often reaches capacity during peak periods like summer, bank holidays, and weekends. Advanced tickets are timed-entry, meaning you must arrive within a specific 15-minute window. In 2026, a "Standard Admission" ticket includes access to the State Apartments, Queen Mary’s Dolls’ House, and St. George’s Chapel, where Queen Elizabeth II is interred. It is important to note that Windsor Castle is closed on Tuesdays and Wednesdays, and the State Apartments may close when The King is in official residence for state business. If you buy your ticket directly from the Royal Collection Trust, you can ask a warden to stamp it at the end of your visit to convert it into a 1-Year Pass, allowing you free return visits for 12 months—a massive value for local travelers or frequent visitors to the UK in 2026.