....assuming you don't have a nice printer and photo paper at home. I just did this and it may seem minor but the cost of a Walgreens passport photo print is over $18 here.

(1) Take passport photo at home (I used my phone). (2) Go to Walgreens, which doesn't have a 2x2 printing option to force people to buy the $18 passport photo package. (3) Order your photo as the minimum square size, 4x4, then click "edit". (4) Add a white border. (5) "Zoom out" until the border occupies the outer half of the frame. (6) Print your $0.44/ea passport photo instantly! Yeeeehaw

The significant edit here is to please be wary of the requirements specific to your passport agency's needs - read and know the nuances about facial expression/lighting/angles/accessories/etc., and consider using passport photo-specific apps online to help you fulfill those requirements. Knowing those nuances can save our butts, here in the States or elsewhere...even if we want or decide to pay the full price of a passport photo (or do anything else dealing with the requirements of a government agency).

Some have mentioned cheaply printing a 2x2 or 2x3 grid of 2x2in photos in one go instead of just printing one photo and wasting space on a thick border. This is smart. This is good. This is the way if you want to use the above tip and aren't doing so on the fly. And if you feel like it.