One of the major losses of sunn pest, Eurygaster integriceps, is its destructive effects on the quality of wheat grains, which is known as the percent damaged kernel. Nymphs and adult bugs by piercing their mouthparts in the grain and transferring salivary enzymes cause gluten destruction and diminish dough quality and bread properties. Grain damage percentage is calculated by the both numerical and weighing methods. An experiment was conducted to compare the relationship between these two methods, using wheat grains delivered to Arak (n = 30), Ghazvin (n = 20) and Lorestan (n = 25) purchase centers. A digital balance with precision of 0.1 mg was used to weigh kernels. Three ten-gram of grain samples were taken from each of the 75 one-hundred-gram samples; so that finally a total of 225 ten-gram samples were obtained. For these samples, the number and weight of damaged and undamaged grains were recorded. In general, sound kernels with an average weight of 34 mg were heavier than damaged ones with average weight of 30 mg. Although, there was a significant difference between the numerical and the weight values, a significant (P <0.0001) and very strong relationship (r = 0.98) was detected between the two methods. Using the equation y = 0.8374x + 0.02, where x and y are the numerical and weight values, respectively, it is possible to convert values from a given method to another one. However, the weighting method is advantageous in terms of simplicity and speed; its application can be reassuring due to the coefficient of conversion.