For those of you who have read my story Slytherin Girl and the sequel, you know that they are based a generation back from the time when Harry himself was at Hogwarts. Because of this, I had to make out a timeline so I could gauge people's ages and times they were at Hogwarts. I spent several hours with all four books, a calculator, an entire pad of paper, a pencil with a good eraser, and the telephone spread around me on the bed making this dang thing out. I noticed a few discrepancies and contradictions, but when this happened, I tried to pick the date that made the most sense.

If any of you happen to like math more than I do (which isn't hard, by the way), and feel like making your own or making corrections to mine, feel free. I based the dates off of the fact that Nearly-Headless Nick's 500th deathday party was in book two, and he died in 1492, putting Chamber of Secrets in 1992. Everything else I figured out by lots of adding and subtracting (and a few instances of throwing sharp or heavy objects across my room in frustration when I had to start all over again) from that.

I decided to put this up on the suggestion of a friend of mine who is trying to write fanfics of her own and keeps asking me about dates. Hope you find it helpful.

I've marked years characters were born, when they started at Hogwarts, and significant events in the books and before. Dates with a * by them are approximate. I'm pretty confident that they're within two years, give or take. For the interesting contradictions in dates, see the bottom. If you have any questions on how I figured these out, feel free to ask. If you see any errors, please tell me. There shouldn't be any, with all the time I spent on this bloody thing, but I suppose it could happen.

1926 T. M. Riddle born

1928 Rubius Hagrid born

1937 Riddle starts at Hogwarts

1939 Hagrid starts at Hogwarts

1941 Chamber of Secrets opened, Hagrid expelled

1943 T. M. Riddle's seventh year

1944 Mr., Mrs., and Tom Riddle die

1945 Albus Dumbledore defeats Grindalwald

1952* Arthur and Molly Weasley born

1960* James Potter, Remus Lupin, Sirius Black, Peter Pettigrew, Severus Snape, and Lily Evans born.

1972 Bill Weasley born

1973 Charley Weasley born

1976 Percy Weasley and Oliver Wood born

1977 Cedric Diggory born

1978 Fred and George Weasley born

1980 Harry Potter, Ron Weasley, Hermione Granger, Neville Longbottom, and Draco Malfoy born

1981 Collin Creevey and Ginny Weasley born, Voldemort's fall, Black sent to Azkaban

1982 Bill Weasley starts at Hogwarts

1983 Charley Weasley starts at Hogwarts

1987 Oliver Wood and Percy Weasley start at Hogwarts

1988 Bill Weasley's seventh year, Cedric Diggory starts at Hogwarts

1989 Charley Weasley's seventh year, Fred and George Weasley start at Hogwarts

1991 BOOK 1, Potter, Ron Weasley, Granger, Longbottom, and Malfoy start at Hogwarts.

1992 BOOK 2, Ginny Weasley and Colin Creevey start at Hogwarts

1993 BOOK 3, Percy Weasley and Wood's seventh years

1994 BOOK 4, Voldemort rises, Cedric Diggory dies

1995 BOOK 5, Fred and George Weasley's seventh years

1996 BOOK 6

1997 BOOK 7, Potter, Ron Weasley, Granger, Malfoy, and Longbottom's seventh years

In book three, it mentions Cedric Diggory as being a fifth year, but in book four, he is a seventh year. Unless he skipped a grade, this is unlikely. I assumed that the age in book four must be correct, or he would not have been able to enter the Triwizard Tournament.

It says in book one that Gryffindor hasn't won a quidditch match since Charley Weasley left Hogwarts. It also says that they haven't won a match in seven years. This implies that he left seven years ago. However, this is impossible, because in book 2, Ginny states that she has been looking forward to coming to Hogwarts since Bill came. Bill is older than Charley. If Charley graduated seven years ago, Bill would have graduated at least eight years ago. Since he started Hogwarts when he was eleven, he would have been at least twenty-five in book one. Ginny was ten in book one. If she had been looking forward to Hogwarts since bill came, she would have been looking forward to it since eight years before her birth. As far as I can figure, the oldest she could have been anyway was one year old, and that is assuming that Charley graduated the year before Ron started at Hogwarts, and Bill the year before that.