Coinsins (kwɛ̃zɛ̃) is a municipality in the district of Nyon in the canton of Vaud in Switzerland.
Coinsins is first mentioned in 1212 as Quinsins. In 1296 it was mentioned as Cuynsins.
Coinsins has an area, , of . Of this area, or 70.8% is used for agricultural purposes, while or 15.1% is forested. Of the rest of the land, or 13.7% is settled (buildings or roads) and or 1.4% is unproductive land.
Of the built up area, housing and buildings made up 4.8% and transportation infrastructure made up 6.2%. Power and water infrastructure as well as other special developed areas made up 1.7% of the area Out of the forested land, 12.4% of the total land area is heavily forested and 2.7% is covered with orchards or small clusters of trees. Of the agricultural land, 48.5% is used for growing crops and 7.9% is pastures, while 14.4% is used for orchards or vine crops.
The municipality was part of the Nyon District until it was dissolved on 31 August 2006, and Coinsins became part of the new district of Nyon.
The municipality is located in the hills above Nyon.
The blazon of the municipal coat of arms is Azure, on a Bend Or a Lizard Vert.
Coinsins has a population () of . , 21.5% of the population are resident foreign nationals. Over the last 10 years (1999–2009 ) the population has changed at a rate of 8.4%. It has changed at a rate of 3.8% due to migration and at a rate of 5.1% due to births and deaths.
Most of the population () speaks French (288 or 78.3%), with English being second most common (27 or 7.3%) and German being third (23 or 6.3%). There are 10 people who speak Italian.
The age distribution, , in Coinsins is; 52 children or 13.2% of the population are between 0 and 9 years old and 48 teenagers or 12.2% are between 10 and 19. Of the adult population, 40 people or 10.1% of the population are between 20 and 29 years old. 58 people or 14.7% are between 30 and 39, 65 people or 16.5% are between 40 and 49, and 48 people or 12.2% are between 50 and 59. The senior population distribution is 48 people or 12.