<P> Historically, the pitch dimensions were imperial and were replaced by metric equivalents in 1998 . The first recorded rules represented what London clubs were using at the time . Surbiton Hockey Club's minutes from 1876 stated that pitches were to be "100--150 yards (91--137 m) long and 50--80 yards (46--73 m) wide". Rules by the Hockey Association of England in 1886 specified "100 yards long by 55 to 60 yards (50 to 55 m) wide". In 1905, the International Rules Board allowed the width of the pitch to be "up to 66 yards (60 m)" but this decision was reversed in 1909 . In 1975, the current width of 60 yards was written into the rules . </P> <P> On artificial surfaces, the field of play should be coloured green, ultramarine blue or signal blue . It is permitted for the run - off portion of the pitch to be an alternative colour . </P> <P> Goals consist of two upright posts placed equidistant from the centre of the backline, joined at the top by a horizontal crossbar . The inner edges of the posts must be 3.66 metres (4 yd) apart, and the lower edge of the crossbar must be 2.14 metres (7 ft) above the ground . The goalposts and crossbar must be white and rectangular in shape with width 50 millimetres (2 in) and a depth of 50 to 75 millimetres (2 to 3 in). </P> <P> The goal must be at least 1.20 m deep at ground level and at least 0.90 m deep at crossbar level . The goal area must be delimited at ground level by a goal backboard and two sideboards of height 460 millimetres (18 in). Affixed to these boards, the posts and crossbar is a net to stop the ball . </P>

What is the height of hockey goal post