While digging through the book to answer a question about the time limit on the games, it seems that a typical length was several weeks:
The twenty-four tributes will be imprisoned in a vast outdoor arena that could hold anything from a burning desert to a frozen wasteland. Over a period of several weeks, the competitors must fight to the death.
However, I do not recall any other mentions of the length of the Games. Is there any canon source that gives an exact duration of the 74th Games?
The 74th Hunger Games lasted for 18 days.
Every night, there’s an anthem and display in the sky which lists the tributes who died that day. This is an important source of information for the remaining tributes – it tells them who’s left in the game. With a few exceptions, we get first-hand accounts of every anthem, and we have enough other information to fill in the gaps.
This gives us a very accurate timeline for the Games, and tells us that Katniss and Peeta win on the 18th day of the Games.
A complete breakdown of the anthems is listed below.
The Games start. As usually happens, many tributes are killed in the initial bloodbath. Katniss narrates a list of the dead, as they appear in the sky:
The first to appear is the girl from District 3. That means that the Career Tributes from 1 and 2 have all survived. No surprise there. Then the boy from 4. I didn’t expect that one, usually all the Careers make it through the first day. The boy from District 5… I guess the fox-faced girl made it. Both tributes from 6 and 7. The boy from 8. Both from 9. Yes, there’s the boy who I fought for the backpack. I’ve run through my fingers, only one more dead tribute to go. Is it Peeta? No, there’s the girl from District 10. That’s it. The Capitol seal is back with a final musical flourish. Then darkness and the sounds of the forest resume.
(Eleven dead, eleven to go)
Somebody starts a fire near the base of the tree where Katniss is sleeping; she’s quickly tracked down and killed by a pack of Careers. At the end of the day, she’s the only casualty:
Night falls, the anthem plays, and high in the sky I see the picture of the girl, who was apparently from District 8.
Nobody dies on the third day:
By the time the anthem plays, I feel remarkably better. There are no faces tonight, no tributes died today.
On the fourth evening, Katniss is driven out of hiding by an artificial wall of fire. She ends up climbing to the treetops, trapped their by the Careers. Katniss uses the anthem to saw through a tree branch, releasing the Tracker Jackers onto the Careers below. We’re not told about any tributes who died today.
In the ensuing tracker jacker attack, Glimmer and the girl from District 4 are both killed. Katniss gets a dose of poison, so she’s knocked out. This is the morning of the fifth day.
When she wakes up, she meets Rue, who tells her that she missed two days:
“Rue, I only woke up today. How many nights did I miss?” The anthem should block out our words, but still I whisper. I even take theprecaution of covering my lips with my hand. I don’t want the audience to know what I’m planning to tell her about Peeta. Taking a cue from me, she does the same.
“Two,” she says. “The girls from Districts One and Four are dead. There’s ten of us left.”
That means Katniss wakes up on day 7.
[Katniss is knocked out]
Katniss wakes up. No mention of dead tributes in tonight’s anthem:
Rue has decided to trust me wholeheartedly. I know this because as soon as the anthem finishes she snuggles up against me and falls asleep.
Two tributes die today:
Up in the sky, I see the seal and know the anthem must have begun. A moment of darkness. They show the boy from District 3. They show the boy from District 10, who must have died this morning. Then the seal reappears.
The boy from District 3 was guarding the Careers’s supplies, which Katniss sabotaged. Katniss and Rue heard the cannon for 10, but never find out how he died.
The boy from District 1 catches Rue in a trap, and kills her; Katniss kills him in revenge. Two deaths today:
Soon the seal’s in the sky, the anthem plays in my right ear. I see the boy from District 1, Rue. That’s all for tonight.
(That leaves six tributes: Katniss and Peeta, Foxface [5], Thresh [11], Cato and Clove [2].)
No deaths today:
It’s been an uneventful day according to the sky. No deaths.
Another quiet day:
I let him drift off to sleep then and attend to my own needs, wolfing down a supper of groosling and roots while I watch the daily report in the sky. No new casualties.
Three quiet days in a row, but the Gamemakers announce a Feast: each of the remaining tributes will have a gift left at the Cornucopia. They want to shake things up.
I watch the sky, hoping for one less opponent at dawn, but nobody appears tonight. Tomorrow there will be faces up there. Feasts always result in fatalities.
The Feast gets violent. Thresh kills Clove as revenge for Rue. Katniss collapses when she gets back from the feast, so we have Peeta to relay the evening’s anthem:
“I know Clove’s dead. I saw it in the sky last night,” he says. “Did you kill her?”
We hear neither cannon blast nor the anthem today; nobody dies. All we get is Katniss and Peeta falling asleep for the night:
Several times, I drift off briefly and then snap awake, guilty and angry with myself. After three or four hours, I can’t help it, I have to rouse Peeta because I can’t keep my eyes open. He doesn’t seem to mind.
“Tomorrow, when it’s dry, I’ll find us a place so high in the trees we can both sleep in peace,” I promise as I drift off.
Katniss and Peeta spend most of the day hiding in their cave; it’s not until the anthem that they realise Thresh has been killed:
For about ten seconds, I catch a distorted glimpse of Thresh’s picture and then he’s gone. Just like that.
(That leaves Katniss, Peeta, Foxface and Cato.)
Sidebar: while staring up at the Moon, Katniss makes an estimate for how long they’ve been in the arena. Her guess is pretty close:
How long have I been gone? I’m guessing it’s been about two weeks in the arena, and there was that week of preparation in the Capitol.
Peeta gathers some nightlock berries, which get stolen by Foxface. Unlike Katniss, she doesn’t recognise them as poisonous, and dies quickly.
The sky lights up with the seal, and I watch Foxface shine in the sky and then disappear from the world forever.
Towards the end of the day, Katniss and Peeta make their way to the lake, expecting a confrontation with Cato. They meet him, but get chased by Muttations up to the Cornucopia. In the ensuing struggle, Cato falls into the pack of Mutts.
Technically he survives the night, although he’s almost certainly close to death:
Night falls and the anthem plays and there’s no picture of Cato in the sky, only the faint moans coming through the metal beneath us.
When a heavily wounded Cato wanders back into range of the Cornucopia, Katniss performs a mercy killing. Shortly afterwards, Katniss and Peeta pull their stunt with the nightlock berries, and the games are over.
According to the Hunger Games wiki page, the 74th Games lasted 18 days.
