Ermont is a commune located in the Val-d'Oise department in the northern suburbs of Paris, France. It is situated approximately 17.2 km (10.7 mi) from the center of the capital city.
The town has a population of around 29,000 inhabitants, making it one of the most significant cities within the Val-d'Oise department. This growth is attributed to rapid urbanization driven by industrialization and railway transport; notably, the population was only 9,000 following the Second World War.