Method to estimate a load behavior in a laundry treatment machine with the steps of: - providing a laundry treatment machine with a drum, a drive motor to rotate the drum around a rotational axis and a controller to regulate an angular speed of the drive motor, - performing a first operation of the laundry treatment machine with a load inside the drum, wherein the controller is operated with first controller parameters (P 1), - determining a first torque signal T em * 1 and a derivative ω ̇ 1 ^ of a first angular speed signal of the drive motor based on the first operation, - performing a second operation of the laundry treatment machine with the load inside the drum, wherein the controller is operated with second controller parameters (P 2), - determining a second torque signal T em * 2 and a derivative ω ̇ 2 ^ of a second angular speed signal of the drive motor based on the second operation, and - determining an inertia (Ĵ t, Ĵ L) and/or a load torque ( T̂ L) caused by the load depending on the first torque signal T em * 1, the second torque signal T em * 2, the derivative ω ̇ 1 ^ of the first angular speed signal and the derivative ω ̇ 2 ^ of the second angular speed signal; characterized in that the first operation and the second operation are performed at a constant desired target angular speed (ω *), while in particular a real speed (ω) oscillates according to the controller parameters (P 1, P 2) and the load; that the first torque signal T em * 1, the second signal T em * 2, the first angular speed signal and the second angular speed signal are transformed into a frequency domain; and that a respective first harmonic of the first torque signal T em * 1, of the second torque signal T em * 2, of the first angular speed signal and of the second angular speed signal are used to determine the inertia (Ĵ t, Ĵ L) and/or the load torque ( T̂ L) using the equation J ^ t = T em * 1 − T em * 2 ω ̇ 1 ^ − ω ̇ 2 ^. - providing a laundry treatment machine with a drum, a drive motor to rotate the drum around a rotational axis and a controller to regulate an angular speed of the drive motor, - performing a first operation of the laundry treatment machine with a load inside the drum, wherein the controller is operated with first controller parameters (P 1), - determining a first torque signal T em * 1 and a derivative ω ̇ 1 ^ of a first angular speed signal of the drive motor based on the first operation, - performing a second operation of the laundry treatment machine with the load inside the drum, wherein the controller is operated with second controller parameters (P 2), - determining a second torque signal T em * 2 and a derivative ω ̇ 2 ^ of a second angular speed signal of the drive motor based on the second operation, and - determining an inertia (Ĵ t, Ĵ L) and/or a load torque ( T̂ L) caused by the load depending on the first torque signal T em * 1, the second torque signal T em * 2, the derivative ω ̇ 1 ^ of the first angular speed signal and the derivative ω ̇ 2 ^ of the second angular speed signal; that the first operation and the second operation are performed at a constant desired target angular speed (ω *), while in particular a real speed (ω) oscillates according to the controller parameters (P 1, P 2) and the load; that the first torque signal T em * 1, the second signal T em * 2, the first angular speed signal and the second angular speed signal are transformed into a frequency domain; and that a respective first harmonic of the first torque signal T em * 1, of the second torque signal T em * 2, of the first angular speed signal and of the second angular speed signal are used to determine the inertia (Ĵ t, Ĵ L) and/or the load torque ( T̂ L) using the equation J ^ t = T em * 1 − T em * 2 ω ̇ 1 ^ − ω ̇ 2 ^.