AbstractThe crown‐gap ratio C is defined as the mean distance between adjacent crowns divided by the mean crown diameter. Previous field studies have established that for a limited range of vegetation stands crown cover is related to C by a general function, viz. crown cover = k/(1 + C)2, where k is a constant. In the present study we investigated the general derivation of the function which relates crown cover to C. The function was then used to determine values for k, a range of point distributions being simulated from semi‐regular to clumped, with mixtures of crown sizes.The relationship between crown cover and 1/(1 + C)2was linear in all cases tested (R2= 1.0). The value of k was shown to depend on the sampling technique used, the degree of clumping, and the range in crown sizes permitted.The variation in k was reduced by using a specific sampling method and limiting the range of spatial distributions and crown sizes considered.The constraints imposed were:1Sampling followed a zig‐zag transect (Delaunay two‐sided model).2Point distributions were not overly clumped.3The range of crown diameters approximated a Gaussian distribution with a relative range of 1–4.Given these constraints the value of k was determined to be 0.806 with a variance of less than 2%. A table is given to convert values for C into crown cover percentages and, if required, to calculate foliage cover per cent.The constraints imposed are considered to be within conditions normally encountered in the field, making the use of C an accurate and simple method by which to estimate crown or foliage cover