How to calculate ratio A : B = C : D B ☓ C = A ☓ D example x : 9 = 4 : 3 x = 4 ☓ 9 ÷ 3 = 12 12 : 9 = 4 : 3 Various Display aspect ratio 1 : 1Square 1.33 : 1 (4:3)35 mm original silent film, TV（NTSC）, IMAX 1.43 : 1IMAX 70 mm wide film 1.50 : 1VistaVision, Chromebook, Pixel Notebook PC, Game Boy Advance, the Surface Pro 3 laplet, Surface Studio 1.6667 : 1A common European widescreen standard, Super 16 mm frame, Nintendo 3DS 1.77 : 1 (16:9)1HDTV 1.85 : 1A common US widescreen cinema standard 2.00 : 1Univisium