A monolithic accelerometer design with zero-g calibration with TSMC 0.18 μm mixed-signal 1P6M process is presented. On-chip digital offset calibration enables compensation of random mechanical offset in the sensor due to process variation. The maximum 21 fF capacitance mismatch can be calibrated. The simulation results show that the whole system have 452.1 mV/g sensitivity. The power consumption is about 1.16 mW. The output noise is 26.85 μg/√Hz at 1KHz.