We present the design and evaluation of a novel precision balance consisting of a thin silica rod suspended on a beryllium copper spring flexure. At opposing ends of the rod are a capacitance sensor and a soleniod/magnet force actuator. When an external force is applied to the silica rod, the resultant deflection of the springs is detected and fed back through a servo controller and current amplifier to the force actuator, thus maintaining a null signal. Consequently, the coil current, which, for relatively small fields, can be considered proportional to its applied force, is monitored as the balance output. Three class I dead weight masses of 2, 5, and 100 mg were used for calibration with six less accurate weights used to verify the linearity of the balance to better than 1%. Using standard vibration isolation techniques and an inexpensive environmental chamber, the present design will measure loading forces up to 1 mN (100 mg) and it has a resolution of better than 70 nN Hz1/2(7 &mgr;g Hz1/2). Presently measuring 40 mm in diameter and 40 mm height this compact design is constructed from low expansivity materials giving a thermal sensitivity of better than 0.03 &mgr;N K−1. Results from a calibration of an atomic force probe are also presented and discussed.