The standard size of international passports, including those issued by the United States, is 4.921 inches by 3.465 inches. The International Civil Aviation Organization (ICAO), which issues passport standards and recommendations to national governments, determines this measurement.
ICAO recommendations also cover the size of the photo on the passport and the type of background it should have. According to 2014 United States guidelines for passports, passport photos must be color and printed on photo-quality paper. Photos must measure 2 inches by 2 inches in size and feature the subject in a size that measures between 1 inch and 1 3/8 inches from the top of the head to the bottom of the chin. The photo must have a plain white or off-white background.