Slickwater fracturing technology has been widely and successfully used for well stimulation because it is inexpensive and causes relatively little formation damage. Friction reducers are always employed in the slickwater fracturing fluid system due to the high friction pressures resulting from the high rates of fluid injection. Polyacrylamide-based polymer is the most common friction reducer in the industry. Many papers have reported the results of tests on friction reducers in water-based fluids in laboratory-scale straight and coiled tube, but few have attempted to address the gap between laboratory and field operation data. For example, laboratory tests using conventional fluid rheological parameters do not accurately predict friction reduction when applied to the large pipes used in field operations. Friction reducer evaluation using full-scale flow loop testing with tube sizes comparable to those used in field operations are typically expensive and require large volumes of fluids, making them impractical. This paper describes an attempt to address the gap between laboratory characterizations and field operations. It reports a study of two common friction reducers studied in a laboratory setup and compares the results with the recorded data from a large number of slickwater fracturing treatments over a wide range of pumping rates and well tube sizes. It introduces a new concept of effective pipe diameter, which, correlated with a fluid velocity profile, permits development of a model to reliably predict field friction reduction from laboratory results. The correlation between laboratory and field data is validated by comparing predictions with actual field data. The study demonstrates that correct lab testing parameters are essential for reliably using laboratory results to predict the effectiveness and performance of friction reducers under field conditions.