A pre-folded file bottom box form (80) created from a unitary blank (10) of corrugated material that is die cut and creased so as to form a series of panels and flaps arranged in three rows (A, B and C) of four panels or flaps each that define four columns (D, E, F and G). The blank (10) includes a first row (A) with four panels (32, 34, 36 and 38) that end up in the box as reinforcing sidewall and end wall panels, a middle row (B) contiguous with the first row (A) and having four panels (20, 24, 28 and 40) that end up in the box as sidewall and end wall panels, and a third row (C) coupled to the second row (B) and including first (16) and second (18) panels and two flaps (12, 14), the first (16) and second (18) panels making up the bottom of the box and the two flaps (12, 14) contiguous with the first third-row panel (16) and making up portions of the two end-walls. The four panels of the first row (A) are folded onto the four panels of the second row (B). The blank is then folded along two of the fold lines (42, 44) located between columns, and the edges (24, 26) of the end panels (30, 20) of the middle row (B) are fastened together, to create the completed form (80).