Each episode of The Legend of Korra comprised about 15,000 drawings.
The series was produced mainly as traditional 2D animation. Animators at South Korea's Studio Mir drew most frames on paper, after which the artwork was scanned for digital processing, coloring, compositing, and final editing. The figure of about 15,000 drawings illustrates the enormous amount of hand-produced artwork behind a single roughly 23-minute episode.
That number does not mean every image on screen was a completely unique drawing. Animation reuses some artwork, holds poses for multiple frames, and combines drawn characters with backgrounds and digital effects. The show also used computer-generated imagery for technically complex elements, including parts of the pro-bending arena and later mecha-suits.
The production schedule was correspondingly intensive: an episode could take roughly 10 to 12 months to complete, with writing, storyboarding, animation, post-production, and retakes overlapping across different episodes and seasons.