A reconfigurable unscented Kalman filter (UKF)-based estimation algorithm for magnetometer biases and scale factors is proposed as a part of the attitude estimation scheme of a pico satellite. Unlike existing algorithms, in this paper, scale factors are not treated, together with other parameters, as part of the state vector; they are estimated separately. After satisfying the conditions of the proposed stopping rule for bias estimation, UKF reconfigures itself for estimation of attitude parameters alone.