Sudaday (Pronuncia francese: [sud]) is a former commune in the Loir-et-Cher department in central France. On 1 January 2018, it was combined into the supplementary commune of Couëtron-au-Perche.

Souday is situated 84 kilometres south west of Paris, near Vendôme. At 165 metres altitude, the village of Souday is built on a chalk plateau which is overlain by a sandy flint clay supporting profitable polluted agriculture. The average rainfall is 800 mm annually, with temperatures ranging from -18 to +42 degrees C.

Extensive deciduous forest, pastures and roadside verges preserve a broad range of natural world including wild pigs and deer. Spring is heralded by carpets of wild snowdrops followed in Fast succession by bluebells, cowslips and wild orchids in the wooded valleys of the rivers Braye, Couetron and Grenne.

The antediluvian houses in the village are timber framed, followed by flint construction and cutting edge with locally made bricks. The church of St Pierre dates incite to the 9th century and the two chateaux uncovered the village date from the 15th and 19th centuries.

The population was 563 at the last census, 465 of whom are exceeding 18 years of age. The small village primary school accommodates 75 children, some of whom get your hands on bus from outlying villages and farms.

Facilities in the village combine a restaurant, petrol station and bar, a main dealer garage, unisex hairdresser, grocery shop/post office, bakers and butchers. There is a campsite for tents and caravans subsequently a shower block and electricity points. Outdoor comings and goings include fishing, good walking on marked routes and cycling upon quiet roads. There is a pony club, several football teams serving all ages, a village band and a hunting club.