Ever since 'Solo Leveling' became the kind of series people quote in comments and freak out over at midnight release threads, I've kept a mental tally of how the story was packaged. The manhwa adaptation concludes with 179 main chapters — that's the number most platforms and official English releases use for the complete, finished manhwa run. You'll also see a prologue and a handful of extra or special pages scattered around release platforms and omnibus volumes; they don't usually change the 179 main-chapter count but they do add nice bits of art and context that fans obsess over.
If you're comparing the manhwa to the original Korean web novel, expect different numbers: the web novel spans around 270 chapters, so it's notably longer on the prose side. The manhwa condenses, rearranges, and visually dramatizes events, which is why sometimes a single manhwa chapter covers what would have been multiple novel chapters. Official English publishers like Tappytoon and some bookstore collections follow the 179-chapter numbering, so that's the number I'd tell a friend who wants to binge the illustrated version.
All in all, when someone asks how many chapters the 'Solo Leveling' manhwa has, I say 179 main chapters, plus a few extras and the richer, longer web novel if you want more depth — and honestly, both versions are worth the read in different ways, at least in my experience.