A fixed point
The only complete date (day, month and year) explicitly cited in the movies is the day of the long-expected party, Bilbo's final birthday celebration in the Shire:
[Bilbo:] The 22nd day of September in the year 1400, by Shire reckoning ...
LOTR:FOTR SEE, scene 2 "Concerning Hobbits"
This happens at the beginning of the FOTR movie, in the first scene after the prologue, only present in the extended edition. Note that the opening scene of TH:AUJ (old Bilbo writing) and the final scene of TH:BOTFA (old Bilbo greeting Gandalf) depict events happening in the very same day.
Movies vs books: in the books, Bilbo's 111st birthday happens in year 3001 TA (Third Age) = 1401 SR (Shire Reckoning); we can easily reconcile this difference supposing a slightly different conversion for Shire reckoning.
General time frames
Bilbo's adventure starts 60 years before his 111th birthday ...
[subtitle:] 60 years earlier ...
[Gandalf:] For sixty years the Ring lay quiet in Bilbo's keeping prolonging his life. Delaying old age.
LOTR:FOTR SEE, scene 10 "The Shadow of the Past"
... and spans about 13 months (let us call this period "the events of TH"):
[Auctioneer:] “This is most irregular. Excuse me, it’s been more than thirteen months since the disappearance. If you are, in fact, Bilbo Baggins and undeceased - can you prove it?”
While there is no precise indication of how much time passes from Bilbo's birthday to Frodo's departure, we know for sure that the four hobbits' adventure spans 13 months too (let us call this period "the events of LOTR"):
[Frodo (voice-over):] Thirteen months to the day since Gandalf sent us on our long journey we find ourselves looking upon a familiar sight.
LOTR:ROTK SEE, scene 75 "Homeward Bound"
Movies vs books: the 60 years gap is in the book too (from 2941 TE to 3001 TE); I couldn't find a book quote concerning the duration of Bilbo's voyage, but the Tale of Years in Appendix B states that he left in 2941 TE and came back in 2942 TE, which is compatible with the 13 months of the movie; Frodo leaves the Shire in September 3018 TE and, together with the other three hobbits, re-enters at the end of October 3019 TE (13 months later).
The obvious chronology difference is the gap between Bilbo's and Frodo's departures from Bag End. In the books it's a 17 year gap; in the movies I think we can assume that Frodo leaves at some point in the year following the long-expected party.
Anyway, this change has no repercussions apart from Aragorn's age at the time of the battle of the five armies, as time expressions in the LOTR movies refer either to a moment following Frodo's departure (so the time difference is not affected by the gap duration), or to an event happened long before (so that a 16 year discrepancy is not so relevant).
The Tale of Years
Notable events in the distant past
- ~ 3,000 years before the events of LOTR: forging of the great rings; Last Alliance of men and elves against Sauron; Sauron defeated; the one ring passes to Isildur; Isildur is ambushed and killed, the ring falls into Anduin
[Elrond:] I was there Gandalf. I was there three thousand years ago when Isildur took the Ring.
LOTR FOTR SEE, scene 24 "The Fate of the Ring"
[Gandalf (reading):] The year 3434 of the Second Age. Here follows the account of Isildur, the High King of Gondor, and the finding of the Ring of Power.
LOTR:FOTR SEE, scene 8 "The Account of Isildur"
Movies vs books: perfectly compatible; the only difference is the compression of the war of the last alliance to just the Dagorlad battle (without the several year long siege of Barad Dur), so that year 3434 SA (which in the books is the year of the Dagorlad battle) in the movies is also the year of Sauron's demise and the end of the Second Age.
- ~ 500 years before the events of TH: Smeagol finds the ring
[Galadriel (voice-over):] History became legend, legend became myth, and for two and a half thousand years the Ring passed out of all knowledge. Until, when chance came, it ensnared a new bearer.
[Galadriel (voice-over):] The Ring brought to Gollum unnatural long life. For five hundred years it poisoned his mind. And in the gloom of Gollum’s cave it waited.
LOTR:FOTR SEE, scene 1 "Prologue"
Movies vs books: perfectly compatible.
- ~ 400 years before the events of TH: a period of peace (for the elves? for the people of Imladris and Lorien?) starts
[Elrond:] “Gandalf, for four hundred years, we have lived in peace. A hard-won, watchful peace.”
Movies vs books: It is not really clear what Elrond is referring to in the movies. The book cronology places in year 2509 TA the goblin ambush to a group of Rivendell elves travelling to Lorien (including Elrond's wife Celebrian), which could fit the definition of "last time the elves were attacked".
In the books there is a period called "the Watchful Peace", lasting about 400 years from 2063 TA to 2460 TA, that precedes the creation of the White Council.
Prelude to the events of TH
- the birth year of many dwarves (including Thorin, Dain, Balin, Dwalin, Oin and Gloin) is depicted in the tapestry found by Bard in Esgaroth
source Weta Workshop
- unspecified date: Thror, father of Thrain, father of Thorin, is King under the Mountain; finding of the Arkenstone
- unspecified date: coming of Smaug, sack of Erebor
- unspecified date: Thrain meets Gandalf and gives him the map and the key
[Thorin:] “My father came to see you before he went missing. What did you say to him?”
TH:DOS SEE, Scene 1 "The Quest for Erebor"
[Thorin:] “How came you by this?”
[Gandalf:] “It was given to me by your father, by Thrain, for safekeeping. It is yours now.”
TH:AUJ SEE, Scene 7 "A Map, a Key and a Contract"
[Thorin:] “Rumours have begun to spread. The dragon Smaug has not been seen for 60 years.”
TH:AUJ SEE, scene 7 "A Map, a Key and a Contract"
- a Midsummer's Eve ~ 45 years before the events of TH: Gandalf meets a very young Bilbo
TH:AUJ SEE, scene 1 "Prologue"
- somewhere in late Summer / early Autumn 2940 TA: Gandalf meets Thorin in Bree
(this is shown in the DOS prologue; "12 months later", as the subtitle says, we meet the dwarves in Beorn's territory)
The events of TH
(the Hobbit trilogy is really scarce in time references)
- somewhere in April 2941 TA: Gandalf visits Bilbo; the unexpected party arrives at Bag End; Bilbo joins Thorin's company and leaves the Shire
no quotation for that, but TH:AUJ SEE BluRay menu has a background clip showing the interior of Bag End at the time of young Bilbo, and there is a wall calendar clearly showing the April page; in the movie, the month name can be seen in the lower left corner of this screenshot:
TH:AUJ, source screencapped.net
- Midsummer's Eve 2941 TA: Thorin's company is in Rivendell; Elrond reads the moon runes
[Elrond:] “Moon runes can only be read by the light of a moon of the same shape and season as the day on which they were written.”
[Thorin:] “Can you read them?”
[Elrond:] “These runes were written on a Midsummer’s Eve by the light of a crescent moon nearly two hundred years ago. It would seem you were meant to come to Rivendell. Fate is with you, Thorin Oakenshield; the same moon shines upon us tonight.”
TH:AUJ SEE, scene 19 "Moon Runes"
- penultimate day of Autumn 2941 TA: Thorin's company is in Esgaroth at Bard's house
[Thorin:] “Tomorrow begins the last days of autumn.”
[Balin:] “Durin’s Day falls morn after next. We must reach the mountain before then.”
TH:DOS SEE, scene 23 "The Home of Bars"
- first day of Winter (Durin's Day) 2941 TA: Thorin's company (minus Kili, Fili, Oin and Bofur) leaves Esgaroth by boat in the morning; before midday they reach the ruins of Dale; finding of the secret door
[Bilbo:] “You do know we’re one short; where’s Bofur?”
[Thorin:] “If he’s not here, we leave him behind.”
[Balin:] “We have to, if we’re to find the door before nightfall. We can risk no more delays.”
TH:DOS SEE, scene 27 "The Parting of the Company"
[Bilbo:] “What is this place?”
[Balin:] “It was once the city of Dale. Now it is a ruin. The desolation of Smaug.”
[Thorin:] “The sun will soon reach midday; let’s find the hidden door into the mountain before it sets.
TH:DOS SEE, scene 28 "The Lonely Mountain"
- a few days later (2 or 3, at a guess): Kili, Fili, Oin and Bofur arrive in Erebor
[Bilbo:] “I have tried talking to him, but he won’t listen.”
[Oin:] “What do you mean, laddie?”
[Bilbo:] “Thorin. He’s been out there for days. He doesn’t sleep. He barely eats. He’s not been himself - not at all. It’s this - It’s this place. I think a sickness lies on it.”
- 22 June 2942 TA: Bilbo is back at Bag End
TH:BOTFA, source screencapped.net