BACKGROUND: Arrays of force sensitive resistors are useful tools for measuring contact pressures, and are widely used in application to the wheelchair seating interface. Naturally, arrays with more sensors provide greater information content; however, operational costs increase steadily with the number of sensors. OBJECTIVE:Here we provide afirst answer to the question: “How many sensors are necessary for accurate pressure mapping?” METHODS: We simulate an ultra-high-density sampling of interfacial pressures (equivalent to a 121 × 121 array), and incrementally down-sample the data (down to a 5 × 5 array). At each simulated sampling density, we calculate three common features (average pressure, maximum pressure, and pressure gradient). Using data collected from a broadly inclusive population of wheelchair users (N = 22), we set a threshold of 90% accuracy of feature extraction for 50% of the population (τμ )a nd for 80% of the population (τσ); data were collected using a commercially available mat with typical sensor spacing. RESULTS: We find that τμ ranged from 9–11 sensors on edge (i.e. 9 × 9t o 11× 11 grid required to faithfully reproduce the three extracted features), and τσ ranged from 13–20. CONCLUSIONS: The common 16 × 16 sensor arrays with approximately 3 cm spacing between sensors, are particularly reliable with high fidelity to grids of higher sampling density, with the possible exception of pressure gradient, which is only moderately accurate, and may require a larger sampling density (20 × 20).