The purpose of this paper was to develop a solution for selecting the right format of web advertisement in Iran. The paper is conducted based on a review of the literature and scrutinizing among more than forty scholarly papers. By reviewing the literature, and developing a theoretical framework, a conceptual model was designed to examine factors explaining right format of advertisement on the internet. Expert's opinion was used to test the conceptual model and using T-student examination, have discovered that seven critical factors affect selection of the right format of the web advertisement. In order to implement the model, we designed a new methodology based on TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) philosophy. In this way, we have defined two ideal frameworks; one for advertisement and the other one for alternatives. Accordingly, the right format of web advertisement is the advertisement that its ideal has a more similarity with the ideal of alternative. To test this methodology, we select 150 Iranian high-ranked websites and found that the model is working properly. The report of websites analysis is placed at the appendix.