Commune in Île-de-France, France Sannois Commune Town hall Coat of arms Location (in red) within Paris inner and outer suburbs Location of Sannois Sannois Show map of France Sannois Show map of Île-de-France (region) Coordinates: 48°58′20″N 2°15′28″E﻿ / ﻿48.9722°N 2.2578°E﻿ / 48.9722; 2.2578Coordinates: 48°58′20″N 2°15′28″E﻿ / ﻿48.9722°N 2.2578°E﻿ / 48.9722; 2.2578 Country France Region Île-de-France Department Val-d'Oise Arrondissement Argenteuil Canton Argenteuil-1 Intercommunality CA Val Parisis Government • Mayor (2020–2026) Bernard Jamet[1] Area 1 4.78 km2 (1.85 sq mi) Population (Jan. 2019)[2] 26,565 • Density 5,600/km2 (14,000/sq mi) Time zone UTC+01:00 (CET) • Summer (DST) UTC+02:00 (CEST) INSEE/Postal code 95582 /95110 Elevation 42–169 m (138–554 ft) (avg.