What were the ages of Bilbo and Frodo for these six major plot points?

Question

I recently begun re-reading the Lord of the Rings trilogy. I'm over halfway through The Fellowship of the Ring now. In spite of having the story in "fresh memory", I still can't remember the details, or didn't understand them to begin with. I did read it carefully, and I know everything that happened, but I have a bad concept of when it happened, in relation to each other.

I'm trying to create a simple "timeline" which states, not using years but rather the ages of Bilbo/Frodo, or the relative time when:

1. Bilbo leaves for his original journey. (Not described in detail in the trilogy.)
2. Bilbo comes back from his original journey. (Not described in detail in the trilogy.)
3. Bilbo leaves for good. (This one I know Bilbo's age for: 111. Not sure about Frodo's.)
4. Bilbo arrives at Rivendell, apparently from just walking around randomly and openly in spite of the dangers. (This confused me as well, even though he no longer had the Ring.)
5. Frodo leaves with his friends and the ponies, first to his fake "new home" and soon after on the great adventure.
6. Frodo arrives at Rivendell and meets Bilbo, apparently after not seeing him for a long time. (To me, it seemed like at most a couple of years, or even months.)

I'd much appreciate to get the ages of both hobbits for these moments, or alternatively the time that has passed between each point. (Ideally, both!)

Answer 1

The Lord of the Rings contains several appendices at the end of The Return of the King, and Appendix B, called The Tale of Years (Chronology of the Westlands), contains a timeline of events.

The following years are 'Third Age', at the end of which the events in The Lord of the Rings takes place. The appendix lists Bilbo's birth year as 2890, and 2968 as Frodo's, but no birth date for both – from the first chapter of The Fellowship of the Ring we know it's September 22nd:

Bilbo and Frodo happened to have the same birthday, September 22nd.

1. The start of Bilbo's journey is in 2941, according to 'The Hobbit' just before May; he is 50 years old.

2. He returns next year (2942), on June the 22nd (in the middle of an auction selling his property) and is 51 years old.

3. Bilbo's farewell feast is on his/their birthday in 3001; he is 111 years old, and Frodo 33. This is mentioned in the first chapter as well:

   Bilbo was going to be eleventy-one, 111, a rather curious number, and a very respectable age for a hobbit (the Old Took himself had only reached 130); and Frodo was going to be thirty-three, 33, an important number: the date of his ‘coming of age’.

4. Bilbo settles in Rivendell the next year (3002); he is 111/112 years old and Frodo is 33/34.

5. Frodo leaves Bag End on September 23, 3018 (by 3018, the appendix starts to list days, since the events happen in rapid succession). Bilbo is 128 by then, and Frodo 50 (about the same age when Bilbo started his journey).

6. The hobbits escape across the Ford of Bruinen, into Rivendell on October 20th that same year, but Frodo doesn't wake up until October 24th. So Frodo and Bilbo haven't seen each other in sixteen years.

Answer 2

All timeline information can be found in The Lord of the Rings, Appendix B: "The Tale of Years (Chronology of the Westlands)". Selecting the relevant pieces of information for your answer:

2890: Bilbo born in the Shire.

2941: Thorin Oakenshield and Gandalf visit Bilbo in the Shire. Bilbo meets Sméagol-Gollum and finds the Ring. The White Council meets; Saruman agrees to anattack on Dol Guldur, since he now wishes to prevent Sauron from searching the River. Sauron having made his plans abandons Dol Guldur. The Battle of the Five Armies in Dale. Death of Thorin II. Bard of Esgaroth slays Smaug. Dáin of the Iron Hills becomes King under the Mountain (Dáin II).

2942: Bilbo returns to the Shire with the Ring. Sauron returns in secret to Mordor.

2968: Birth of Frodo.

3001: Bilbo's farewell feast. Gandalf suspects his ring to be the One Ring. The guard on the Shire is doubled. Gandalf seeks for news of Gollum and calls on the help of Aragorn.

3002: Bilbo becomes a guest of Elrond, and settles in Rivendell.

3018 [...] September 23: Four Riders enter the Shire before dawn. The others pursue the Rangers eastward,and then return to watch the Greenway. A Black Rider comes to Hobbiton at nightfall. Frodo leaves Bag End. Gandalf having tamed Shadowfax rides from Rohan.

October 20: Escape across the Ford of Bruinen.
October 24: Frodo recovers and wakes. Boromir arrives in Rivendell at night.

In The Fellowship of the Ring, Bilbo and Frodo have a joint birthday party; Bilbo is 111, as you recall ("eleventy-one"), and the sum of their ages is 144 ("one gross"), so that makes Frodo 33. This fits with their birth years and the year of the Long-Expected Party as mentioned above.

So going through the events you mentioned and checking ages and the relative timeline (noting that the other answer also found proof that their shared birthday is 22 September):

• Bilbo makes his journey "There and Back Again" in The Hobbit at 50-51 years old (he leaves in spring and returns the next spring, so one birthday while he's away). Frodo is born 26 years later.
• Bilbo leaves for good and settles in Rivendell at 111 years old; Frodo is 33 years old at this time.
• Frodo leaves his old home and travels to Rivendell sixteen years later, at 50 years old, when Bilbo is 128 years old.