The SG postcode area, also known as the Stevenage postcode area, is a group of nineteen postcode districts in England, which are subdivisions of fifteen post towns. These postcode districts cover north Hertfordshire (including Stevenage, Baldock, Buntingford, Hertford, Hitchin, Knebworth, Letchworth, Much Hadham, Royston and Ware) and east Bedfordshire (including Arlesey, Biggleswade, Henlow, Sandy and Shefford), plus a small part of south-west Cambridgeshire and a very small part of Essex.