幸福指数 (Koufuku Shisuu) is 40meterP's long-awaited third doujin album. It contains tracks, sung by Hatsune Miku and GUMI. Featured is one of 40mP's best known hits, "Shiryoku Kensa". The mastering was done by Signal-P. It was first released at THE VOC@LOiD 超 M@STER 20.
A crossfade of the album can be heard on Niconico.