Arriva UK operates a bus from Crawley to Windsor Castle every 5 minutes. Tickets cost $5 - $8 and the journey takes 20 min. 2 other operators also service this route.
How to get from Crawley to Windsor Castle
From Crawley, Bus Station (Station Way) bus to Gatwick Airport London, bus to Heathrow Airport Terminal 5, Heathrow Terminal 5, line 8 bus to Windsor Town Centre, WH Smith (Central Station Access Road), then walk to Windsor Castle. 2 h 36 min £21. From Crawley taxi to Windsor Castle. 48 min £188. From Crawley drive to Windsor Castle. 48 min £8.