Zoning is a standard method of measuring retail premises to calculate and compare their value. It is used by both public and private sector surveyors.

Zoning as a method has been applied in the UK to the analysis of shop rents and properties for rating purposes since the 1950s.

Shop or retail premises are divided into a number of zones each of a depth of 6.1 metres - or 20 feet.

Zone A closest to the window is most valuable with the value decreasing with distance from the frontage: Zone B is the next 6.1 metres, then Zone C until the entire depth of the retail area is allocated to a zone  - anything after Zone C is usually defined as the remainder.

The established valuation convention is to halve back from Zone A, with Zones B onwards assessed ‘in terms of Zone A’ (ITZA): Zone B =A/2; Zone C=A/4. Zone D, which is usually the remainder of the retail area after Zone C, is assessed as A/8 and any ancillary space will probably be valued as A/10.

Beckett and Kay's note on shop rental values explains how zoning works in practice.