"He could abandon the plan and simply learn to live with the memory of what his father had done on a summer's day more than twenty years ago..."
In various places around the Lexicon, ages are given for the main characters. Some character’s ages are fairly easy to determine. However, the ages of the Marauders and those who were at Hogwarts with them are a bit tricky to work out. Rather than explain over and over how we have determined those ages, we’ve created this page and we’ll link to it.
It’s important to note that the range of years for the Harry Potter books has now been established. Those dates are canon and are included here without further explanation. If you want to learn more about how we know the years, you can read the Explainer for that topic.
So how do we know when Snape and the Marauders were born?
1) James, Lily, Snape, Sirius, Remus, and Peter were all in the same year at Hogwarts. We know this because they all took their OWLs together in book five. So any fact we discover about one of these people applies to the others as well.
2) Sirius was about 22 when he was sent to Azkaban (Rowling states on her website). Since we know that this happened in late 1981 or early 1982, we can place his birth year at 1959 or 1960.
3) JKR tells us that Snape was “35 or 36” in an interview with Comic Relief (CR). This interview took place after the release of GF, so assuming that she was referring to Snape’s age at that point in the saga, which was 1995. Therefore we know that Snape was born 35 or 36 years before 1995, which is 1959 or 1960. So far things are matching up quite well.
There are more clues.
4) The events Harry sees in the Pensieve are described in the text as being “more than twenty years ago”:
“He could abandon the plan and simply learn to live with the memory of what his father had done on a summer’s day more than twenty years ago…” (OP29)
This strongly suggests a time frame of 21-24 years before the spring of Harry’s fifth year (1996). Snape and the others took their OWLs, therefore, around 1975. These facts indicate a birth year for Snape–and therefore also for James, Lily, and the others of their year at Hogwarts–of about 1960. Harry’s parents, then, were about twenty years old when Harry was born and they and their classmates were born in 1959 or 1960.
5) And now we have the Black Family Tree — and complications
The recent release of the Black Family Tree complicated things. On that document, Sirius’ name and birthyear are blasted off, unfortunately. However, we can see that Bellatrix was born in 1951. Bella was at Hogwarts with Snape, according to this quote from book four:
“Snape knew more curses when he arrived at school than half the kids in seventh year, and he was part of a gang of Slytherins who nearly all turned out to be Death Eaters.” Sirius held up his fingers and began ticking off names. “Rosier and Wilkes – they were both killed by Aurors the year before Voldemort fell. The Lestranges – they’re a married couple – they’re in Azkaban…” (GF27)
Since Bella was born in 1951, she started Hogwarts in 1962 or possibly 1963 if she was born after September 1. We’re going to go with the latest possible date for Bella’s first year–the 1963-1964 school year–and work our way up. Here’s Bella’s school years:
1963-1964 – First year
1964-1965 – Second year
1965-1966 – Third year
1966-1967 – Fourth year
1967-1968 – Fifth year
1968-1969 – Sixth year
1969-1970 – Seventh year
For this to work, Snape must have been a student at Hogwarts no later than September of 1969. We have seen that all other clues point to a birth year for Snape and the Marauders of 1959 or 1960. Even if we go with the earlier date, 1959, there is really no way that Snape could have been at Hogwarts with Bella if the Family Tree is correct.
To be fair, the estimate of 1959 or 1960 is just that, an estimation. It could be that Snape was born in 1958, which would allow him to be a First Year when Bella was a Seventh Year. It’s also reasonable to say that Sirius might simply be mistaken, that Bella had left by the time he and Snape because students; perhaps she only seemed to be there when he remembers back.
Note: the birthyear of 1958 only works for children born before Sept. 1st. If Lily, James, Pettigrew and Sirius were born after that, their birthyear would be 1957.
Honestly, I tend to think that Jo simply made a mistake on the Family Tree and should have moved Bella’s birth year up to somewhere around 1955.
However, at the Lexicon we do our best to make everything agree with canon, even when the reliability of that canon source is questioned. We know that Jo probably hasn’t worked out all these math details.
Conclusion: the canon sources are in mild conflict and so our dates need to be approximate. So, on the Lexicon we will list the birth year of Snape, Lily and the Marauruders as c.1959 knowing that a range from 1957-1959 is possible. Bear in mind that this date will never be settled for certain until Jo gives us more information.
P.S. Give us a few weeks for all of our pages to catch up.
This essay gives a good picture of how we were trying to piece together clues before all the novels were published and before Rowling started adding canon information in interviews, on Twitter, and on Pottermore. Of course, this entire question was resolved with the release of book seven which listed the birth years for James and Lily on their tombstones.