After the 2017 merger Grono has a population () of . , 32.3% of the population are resident foreign nationals. In 2015 a small minority (155 or 15.2% of the population) was born in Italy and 89 or 8.7% of the population was born in Portugal. Over the last 4 years (2010-2014) the population has changed at a rate of 6.72%. The
birth rate in the municipality, in 2014, was 13.9, while the
death rate was 7.0 per thousand residents. The age distribution, , in Grono is; 93 children or 10.2% of the population were between 0 and 9 years old. 40 teenagers or 4.4% were 10 to 14, and 40 teenagers or 4.4% were 15 to 19. Of the adult population, 107 people or 11.7% of the population were between 20 and 29 years old. 130 people or 14.2% were 30 to 39, 145 people or 15.8% were 40 to 49, and 138 people or 15.1% were 50 to 59. The senior population distribution was 87 people or 9.5% of the population were between 60 and 69 years old, 68 people or 7.4% were 70 to 79, there were 58 people or 6.3% who were 80 to 89, and there were 10 people or 1.1% who were 90 to 99. In 2015 there were 385 single residents, 507 people who were married or in a civil partnership, 56 widows or widowers and 72 divorced residents. In 2014 there were 428 private households in Grono with an average household size of 2.32 persons. Of the 273 inhabited buildings in the municipality, in 2000, about 63.7% were single family homes and 15.8% were multiple family buildings. Additionally, about 24.2% of the buildings were built before 1919, while 13.2% were built between 1991 and 2000. In 2013 the rate of construction of new housing units per 1000 residents was 2.01. The vacancy rate for the municipality, , was 0.76%. ==Heritage sites of national significance==