To determine your spacebar size, you need to measure the length of the spacebar keycap in millimeters and divide it by 19. This will give you the unit size of your spacebar. For example, if your spacebar is 114 mm long, then your spacebar size is 114 / 19 = 6u. Our spacebar size ranges from 5.57u to 7u, so you can choose the one that fits your keyboard best.