OBJECTIVES: To present simple, objective, and customizable cost estimation formulas to compare per-attack treatment costs of four recently FDA-approved Hereditary Angioedema (HAE) products.  METHODS: Products developed for small orphan disease populations such as hereditary angioedema (HAE) are predictably costly. Comparing treatment costs among new HAE therapies is complicated by differences in dosing recommendations and re-dosing probabilities. We propose a simple cost estimation formula that factors in the non-static variables of body weight and re-dosing likelihood per attack based on official prescribing recommendations and published clinical study data. Other administrative or indirect costs were not factored into the formulas. RESULTS: Formulas were developed that allow insertion of local acquisition costs for any of the HAE products, according to the quantity of vials or syringes required for initial dosing. A weighted percentage of the cost of the initial dose was added to determine the total cost, factoring in the anticipated need for re-dosing. For products having more than one published re-dosing frequency, the lowest reported frequency was used as a conservative approach. Specific cost estimation formulas address three theoretical patient weight categories: ≤40 kg (to reflect small adults or pediatric patients), a standard 75 kg adult, and obese patients weighing between 100-125 kg. CONCLUSIONS: While therapy choices in HAE should be primarily driven by clinical factors and patient preferences, cost of treatment can be an important consideration if multiple options are considered equally appropriate. The formulas presented provide a simple, objective means of quickly comparing direct product costs for treating an HAE attack using local pricing figures.