The Human Equation is the sixth album from the progressive rock project Ayreon by Dutch musician Arjen Anthony Lucassen, released on 25 May 2004 via Inside Out Music.

As with other Ayreon albums, it features guest appearances from several musicians previously unrelated to the project, including James LaBrie of Dream Theater, Mikael Åkerfeldt of Opeth, Eric Clayton of Saviour Machine, and Devin Townsend, performing music arranged and written by Lucassen.

While his Wife (Marcela Bovio) and Best Friend (Lucassen) are at his side in the real world, Me, trapped in his own mind, encounters representations of his own feelings and recalls his life from his childhood to his crash.

The album explores the idea of psychological rebirth, and follows the story of a man who, after falling into a coma following a car crash, is confronted with his past, his emotions, and his current situation as he lays trapped inside his own mind.

All lyrics are written by Arjen Anthony Lucassen except where noted; all music is composed by LucassenDisc 2 has ten four-second and one nine-second hidden tracks which introduce "Day Twelve: Trauma".