Pls reference bag dimension ( Length x Width x Thickness ) before your order it. 11.6 inch bag : Outer dimension : 305 x 215 x 35 mm . Inner dimension : 295 x 205 x 30 mm. 12 inch bag : Outer dimension : 330 x 230 x 35 mm . Inner dimension : 310 x 215 x 30 mm. 13.3 inch bag : Outer dimension : 350 x 245 x 35 mm . Inner dimension : 330 x 230 x 30 mm. 14 inch bag : Outer dimension : 370 x 255 x 40 mm . Inner dimension : 360 x 250 x 30 mm. 15 inch bag : Outer dimension : 395 x 275 x 40 mm . Inner dimension : 385 x 270 x 30 mm (12 inch bag is very big for macbook 12 inch, pls order 11.6 inch bag for macbook 12 inch ) For Macbook New 13.3 inch, A1706, A1708, A1932, A1989, A2159, A2179, they all are same dimension bag, Bag outer dimension : 330 x 230 x 35 mm , Inner dimension : 310 x 215 x 25 mm . Bag For Macbook A1466, it is same size bag with normal 13.3 inch bag. 13.3 inch bag is not good fit for all brand laptop 13.3 inch, Such as For macbook new 13.3 inch, own thin screen frame, the laptop outer length is 304 mm,but for macbook old 13.3 inch laptop outer length is 325 mm. 14 inch and 15.6 inch bag is aslo cann't perfect fit all brand laptop 14 and 15.6 inch, they all need reference laptop length and width diemension. Ultrabook 13 inch laptop may need choice 12 inch bag. Ultrabook 14 inch laptop may need choice 13 inch bag. Ultrabook 15 inch laptop may need choice 14 inch bag. Pls kindly contact with us if you cann't sure which size bag is fit for your laptop, pls tell us what is your laptop length and width in mm before you make order.then we can recommend which size bag good for you.