The amplitude modulation atomic force microscopy (AM-AFM) - also known as "tapping mode'' - is the workhorse under the scanning probe microscopy techniques applied in ambient conditions and liquids. During the approach towards the sample surface the oscillation of a cantilever with integrated tip is detected by a change of the oscillation amplitude and phase. Unfortunately, the analysis of these signals is greatly complicated by the nonlinearity of the tip-sample force resulting in instabilities and hysteresis. Nonetheless, it has been shown how the energy dissipation between tip and sample is linked to the phase. In our talk we present an approach enabling also the quantitative reconstruction of tip-sample forces in amplitude modulation AFM. The proposed algorithm is based on the systematic recording of amplitude and phase vs. distance curves. The reliability of the method is demonstrated by numerical verifications. Experimental applications demonstrate its practicability.