There's no single 'average' that fits everyone, which I think a lot of folks miss when they ask this. Reading speed varies wildly. If I base it on the page counts from my box set, the trilogy totals around 1,450 pages. The standard 'average reading speed' you see online is about 300 words per minute, and these books are pretty typical YA prose—not overly dense. Doing the math, that puts the total word count somewhere in the ballpark of 375,000 words.
For a moderately fast adult reader, that could mean maybe 12-15 hours of total reading time, spread out. But I've seen people devour 'The Hunger Games' in a single weekend because the pacing is so relentless, while others, especially younger readers or those reading in a second language, might take a month of consistent evening sessions. The chapter cliffhangers in 'Catching Fire' specifically make it a real page-turner; you lose track of time and end up reading far past your bedtime, which skews any 'average.'
So instead of a number, I'd say the commitment feels like a very intense, immersive week for a dedicated reader, or a satisfyingly long journey over a few weeks if you're savoring it. The trilogy's structure, with each book's tension ramping up, naturally compresses reading time as you go—I definitely read 'Mockingjay' faster than the first book because I had to know how it ended.