Soil water retention is important for plant growth and preventing contamination. A new model based on fractional bulk density was developed to estimate soil water retention curves. This model uses particle size distribution, bulk density, and residual water content as input parameters. The model was tested on various soil types and showed effectiveness for all textures and bulk densities. Changes in bulk density and residual water content had a bigger impact on estimation than particle size distribution. This model provides an easy way to understand how soil bulk density affects water conservation in different soils.