Voltammetric peak of adsorbed electroactive system with lateral interactions may be described theoretically by a parametric equation; no exact explicit current-potential relation is achievable. Approximate calculation algorithm (LAT) is presented for establishing this relation; separate version of algorithm (LAT1) has been developed for negative values of the interaction parameter. These algorithms allow performing calculations with high accuracy. Unfortunately, precision has been achieved at the expense of simplicity: LAT makes use of up to nine adjustable coefficients. Accuracy of LAT has been compared with accuracy of GLI equation proposed by Alévêque and Levillain Electrochem Commun 67:73–79, 2016.