Windsor Castle is about 22.5 miles from central London, which is 35 to 45 minutes by car. Some routes take almost an hour by car.
By public transportation, the ride takes about 50 minutes from central London. However, leaving from other parts of London can take more or less time; from western London's Paddington Station, the trip can be under 30 minutes.
Windsor Castle is open to the public from 9:45 a.m. to 5:15 p.m. from March to October and 9:45 a.m. to 4:15 p.m. from November to February, although the last guests let in are at 4 p.m. and 3 p.m., respectively.