The Condensation Particle Counter (CPC) is an effective instrument for measuring the number concentration of aerosol particles in different environments. With only a few exceptions, CPCs are bench instruments with limited portability for use in the field, and have a cost that prevents their use in large numbers for distributed air quality measurements. This has motivated the development of compact and cost-effective CPCs that are already available in the market. Here we test the performance of such a CPC, designed and built by National Air Quality Testing Services Ltd (NAQTS), Lancaster, UK, which is a part of the V2000 compact air quality monitor that also includes gas sensors. The tests were carried out using monodisperse particles produced by atomization and electrical mobility classification. We found that the NAQTS V2000 CPC has a 50% detection efficiency for particles having diameter of ca. 14 nm. Our results also show that the coincidence error of the core CPC occurs at concentrations higher than 1 × 104 #/cm−3. Considering that the standalone CPC employs an ejector pump that provides a nominal dilution factor between 20 and 50 at its inlet, the coincidence error threshold of the system when sampling particles from ambient air is 2–5 × 105 #/cm−3. To extend its range for aerosols with particle concentrations by one order of magnitude higher, and thus expand its capabilities for a wide range of applications, we provide a simple correction equation. Overall, our results demonstrate that the NAQTS V2000 CPC is a highly effective instrument, and considering that it is currently the most cost-effective CPC in the market, to the best of our knowledge, makes it a highly attractive solution for air quality monitoring.@en