Gagny is located in Paris city, France at the 48.8833, 2.5333 coordinates. Distance from Gagny to other cities. are listed below, click on the city name to find distance between. Distance from Gagny to Cergy-Pontoise 37 km, to Saint-Quentin-en-Yvelines 40 km, to Boulogne-Billancourt 21 km. The green marker indicates the location of Gagny.