This paper examines the differential effects that taxing sugar-sweetened beverages (SSBs) by calories and by ounce have on beverage demand. Based on sales data from supermarkets across four New York state regions, researchers predict that a calorie-based SSB tax is more effective than an ounce-based tax because it achieves more calorie reduction with a smaller loss in consumer surplus. A 0.04 cent per-calorie tax on SSBs is predicted to reduce the consumption of beverage calories by 9.3 percent versus a reduction of 8.6 percent from a half-cent per-ounce tax. Applying this percentage to beverages purchased from a variety of retail outlets, and assuming consumer purchasing behavior remains consistent across all venues, a 0.04 cent per-calorie tax would reduce total per person consumption by about 5,800 calories annually, while a half-cent per-ounce tax would achieve less of a reduction. A calorie-based beverage tax cost an estimated $1.40 less in consumer surplus loss than an ounce-based tax, per 3,500 beverage calories reduced.