Desiccation cracking has been aggravated by the frequent extreme weather events and climate change in recent years. The presence of these cracks compromises the integrity of soil structures and significantly contributes to rainfall infiltration, slope stability, as well as soil deformation. According to tensile failure theory and Hookean elastic equation, an analytical model was established to predict crack depth under continuous desiccating conditions. The essential input parameters for the modelling are the modulus ratio and tensile strength, which can be determined through uniaxial tensile and shear tests. The maximum crack depth is estimated based on the suction change profile of the soil under investigation. Herein, the suction change profiles were developed from volumetric water content monitoring at various depths and utilizing the soil water characteristic curve (SWCC) of the investigated soil. Validation of the proposed method was conducted through laboratory simulations, specifically in the context of crack formation in granitic soils under continuous drying conditions. The predicted crack depth, in a range of 0.22 ∼ 0.30 m, closely aligned with the observed values. Collectively, for a specific soil with given elastic parameters and strength, crack depth can be estimated through suction change. This approach, compared with existing crack modeling methods, offers a simple and efficient way for crack depth estimation, holding promise for practical applications.