The 2013 kia optima has a 24 inch wiper on the driver's side an an 18 inch wiper blade on the passenger side. this is very common to find on vehicles because the driver's side needs to be cleared off more to clear a larger area to let the driver see where they are going. when it is time to buy new wiper blades you should always get oem or greater blades. cheap blades may seem like a good deal, but they break down faster and can also cause scratching on your glass if the rubber gets too hard as it wears out. there are also more premium blades on the market like rain-x. these install a hydrophobic barrier on your car when you drive and help make it easier to see.
The 2013 kia optima will need a 24 inch blade for the driver's side and an 18 inch blade for the passenger's side.