An input interface (3) comprises a display (23), a window (21) overlaid on the display (23), and a housing (13-15) supporting the window (21). A first sensor arrangement (31, 32) is configured to sense a position of a touch action on the window (21) in two dimensions. The first sensor arrangement (31, 32) comprises a first plurality of conductive traces (32). A second sensor arrangement (41-43) is configured to sense a magnitude of a force applied by the touch action onto the window (21). The second sensor arrangement (41-43) comprises a second plurality of conductive traces (41, 42) and a force sensing material (43). The first plurality of conductive traces (32) and the second plurality of conductive traces (41, 42) are positioned on an inner face (30) of the window (21) and attached to the inner face (30) of the window (21). The force sensing material (43) is attached to the inner face (30) of the window (21) such that the force sensing material (43) contacts the second plurality of conductive traces (41, 42).